Pierolapithecus: The Catalonian Ape

File:Pierolapithecus catalaunicus (Kopie).jpg
A replica of the fossilized skull of Pierolapithecus catalaunicus
Image Credit: Nasobema lyricum, https://commons.wikimedia.org/wiki/File:Pierolapithecus_catalaunicus_(Kopie).jpg

In terms of Mammalian evolution, the great apes (or “Hominidae”) are a recent development. They first appeared around 13-15 million years ago in the Miocene period and would go on to diversify into a variety of different species. Among these are, of course, the various species of human, including the only surviving one, our own (Homo sapiens). This one member of the great ape lineage now has a population of roughly 7 billion, lives across the entire globe, and has changed the landscape of the earth to such an extent that many geologists think that this modern age is its own distinct geological period (known as the Anthropocene). But to understand the earliest evolution of the great apes (and by extension our own species) studies must be made of the often fragmentary remains of these first apes. One such ape was discovered in 2004 in the Catalonia region of Spain. This species is Pierolapithecus catalaunicus.

The name Pierolapithecus catalaunicus comes from the village where the first fossils were discovered: “Els Hostalets de Pierola”. These first finds consisted of cranial (the top of the skull) and postcranial (the back of the skull) elements as well as some isolated teeth. Moving down, further remains were found of the thorax (chest and pelvis), lumbar region (the lower spine near the hips) and the wrist. Reconstructions from these remains estimate that it wouldve weighed around 55 kilograms, around the same as a female chimp. Studying these bones and further finds gave paleontologists clues as to how Pierolapithecus may have lived. For example, the structure of the wrist, thorax and lumbar bones suggests that Pierolapithecus would have spent most of its life in the trees, rather like the modern-day Orangutan.

Pierolapithecus is hypothesized to be a basal (or early) member of the great apes, but while it can be identified as one (e.g. it shared the same facial pattern as modern great apes, with a particularly Gorilla like face), it had yet to evolve all of their features (e.g. their fingers are not like great apes). Think of it as a kind of transitional form, or to use the overused (and misleading) term “missing link”, between the great apes and the “lesser apes” (i.e. Gibbons and Siamangs). Dating of the sediments around the bones indicate that they were roughly 12.5-11.9 million years old, putting Pierolapithecus in the middle of the Miocene period and suggesting that it was one of the oldest of the great apes. These bones also possess marks made by carnivores, indicating that they were either scavenged, or that there were active predators that Pierolapithecus had to watch out for.

Another feature that links Pierolapithecus to great apes is that it is thought to have had orthogrady. This term describes an animal that walks upright on its hind legs, with its spine curved partly upright, for long periods of time. Further, Pierolapithecus’ patella bone (a bone found on the upper knee) is like modern great apes and allows mobile movement of the knee. Combined with its moderately sized hands and a broad and shallow thorax, it suggests that Pierolapithecus was adapted more for vertical climbing and movement rather than suspending and couldn’t swing between branches. This is certainly weird considering that some modern great apes, like Chimpanzees, can swing. Therefore the ability to swing between branches must have evolved multiple separate times in great apes, and isn’t an ancestral trait. Another implication is that if a mostly tree dwelling animal possessed orthogrady then maybe upright walking didn’t originate just for walking on the ground. Instead orthogrady would have been used for walking along the branches of trees first before later being co-opted for a terrestrial lifestyle in humans their closest ancestors. One advantage of this is that it would have freed up Pierolapithecus’ arms to reach and grab ripe fruit and leaves that were previously out of reach.

But where on the great ape family tree was Pierolapithecus? well it is debated whether it is a basal hominid (e.g. ancestral to all living great apes) or a basal hominin (e.g. ancestral to humans, chimps, bonobos and gorillas only). Evidence that supports it being a basal hominid include a study in 2012 (Pérez de los Ríos, Moyà-Solà & Alba 2012) that analysed areas of the skull including the pneumatic structures, nasal area and palate. This analysis showed that these features were intermediate between basal hominoids and pongines (the ape family that contains Orangutans), and therefore that Pierolapithecus was more hominid than hominin. This study seems to have put the hominid idea in the driving seat, but if Pierolapithecus were to be a basal hominin, and on the line that produced humans and their close relatives then this raises another interesting possibility. It is often thought that all early hominid and human evolution took place within Africa. Then human relatives, and humans themselves, migrated out of Africa and spread to new lands in Europe, Asia and (in the case of humans) the rest of the world. However, Pierolapithecus was discovered in the Catalonia region of Spain! If the early human ancestor that Pierolapithecus is closely related to also lived in Europe then early human ancestors must have migrated from Southern Europe into Africa, where they would then continue to evolve and produce multiple human species, and humans themselves. In short, our very earliest ancestors may have originated in Europe, not Africa! Of course, this is just a theory and further fossil evidence from other stem hominids is required to prove or disprove it. It is equally plausible that Pierolapithecus may be an outlier, a side branch of stem hominids that migrated from Africa into Southern Europe while the early human ancestor lived in Africa. It is also possible that the range of Pierolapithecus would have extended into Africa too, we just have only found their remains in Spain at the moment. We cannot be sure right now, but it is a fascinating possibility!

Pierolapithecus, this seemingly unassuming great ape from Spain, is certainly an intriguing primate and a key piece of unlocking the puzzle box that is figuring out how this great, and eventually world changing, lineage came to be.

A diagram indicating where Pierolapithecus is thought to currently lie in great ape evolution
Image Credit: Institut Català de Paleontology, https://www.flickr.com/photos/icp_mcrusafont/6776869406

References/Further Reading

Moyà-Solà et. al. 2004: the paper that first described Pierolapithecus catalaunicus

Moyà-Solà, S., et al. (2004). “Pierolapithecus catalaunicus, a New Middle Miocene Great Ape from Spain.” Science 306(5700): 1339-1344.

Crompton, Vereecke & Thorpe 2008: a paper that described locomotion and orthogrady/pronogrady movement among early stem hominids.

Crompton RH, Vereecke EE, Thorpe SK. Locomotion and posture from the common hominoid ancestor to fully modern hominins, with special reference to the last common panin/hominin ancestor. J Anat. 2008 Apr;212(4):501-43. doi: 10.1111/j.1469-7580.2008.00870.x. Erratum in: J Anat. 2008 May;212(5):703. PMID: 18380868; PMCID: PMC2409101.

Hammond et. al. 2013 paper, published in the Journal of Human Evolution, on the pelvic morphology of Pierolapithecus and comparisons with other stem hominids

Ashley S. Hammond, David M. Alba, Sergio Almécija, Salvador Moyà-Solà, Middle Miocene Pierolapithecus provides a first glimpse into early hominid pelvic morphology, Journal of Human Evolution, Volume 64, Issue 6, 2013, Pages 658-666, ISSN 0047-2484, https://doi.org/10.1016/j.jhevol.2013.03.002.

Nakatsukasa 2019 paper on the spinal morphology of Miocene apes like Pierolapithecus and the evolution of Orthogrady

Nakatsukasa M. (2019) Miocene Ape Spinal Morphology: The Evolution of Orthogrady. In: Been E., Gómez-Olivencia A., Ann Kramer P. (eds) Spinal Evolution. Springer, Cham. https://doi.org/10.1007/978-3-030-19349-2_5

Pina et. Al. 2014 paper on the structure of Pierolapithecus’ knee bones in relation to its skeleton, and what can be inferred about its climbing and swinging ability

Pina M, Almécija S, Alba DM, O’Neill MC, Moyà-Solà S (2014) The Middle Miocene Ape Pierolapithecus catalaunicus Exhibits Extant Great Ape-Like Morphometric Affinities on Its Patella: Inferences on Knee Function and Evolution. PLoS ONE 9(3): e91944. https://doi.org/10.1371/journal.pone.0091944

• Pérez de los Ríos, Moyà-Solà & Alba 2012 paper that examined the skull areas containing the nasal region, pneumatic structures and palate. Their study provides evidence that Pierolapithecus is a basal hominid.

Miriam Pérez de los Ríos, Salvador Moyà-Solà, David M. Alba, The nasal and paranasal architecture of the Middle Miocene ape Pierolapithecus catalaunicus (primates: Hominidae): Phylogenetic implications, Journal of Human Evolution, Volume 63, Issue 3, 2012, Pages 497-506, ISSN 0047-2484, https://doi.org/10.1016/j.jhevol.2012.05.012.

Aepyornis and the Elephant Birds of Madagascar

File:Aepyornis maximus 01 L.D..jpg
A front view reconstruction of Aepyornis.
Image Credit: Acrocynus, https://it.wikipedia.org/wiki/File:Aepyornis_maximus_01_L.D..jpg

While it seems like I already know a bit about prehistoric life, before each of these blog articles I make sure to do my research on the animal that I aim to talk about, as any blog writer should do regardless of their subject area. During my research I not only broaden my knowledge, but also gain an extra appreciation for the animal in question. In the case of todays subject, Aepyornis (Greek for “high bird”), more commonly known as the “Elephant Bird”, my research showed just how little I actually knew about it. Aepyornis was a much more fascinating animal than I had realised (not just “a big ostrich”), and in this blog I aim to put the spotlight on this underrated animal.

For starters there wasn’t just one “Elephant Bird”; there was a whole family of them! “Elephant Bird” is the common name given to a family of flightless, bipedal, ostrich-like herbivorous birds from Madagascar known as the Aepyornithae. The “Elephant Bird” name originates from tales of the “Roc”; a legendary giant bird spoken of by Arab traders and written about by the famous explorers Marco Polo (13th century) and Ibn Battuta (14th century). It was also one of the monsters that the adventurer Sinbad encountered in “The Arabian Nights” tales (first published in the 18th century). It was said to be so big that it could carry an elephant in its talons. Polo in all likelihood based his Roc description on accounts of large, lemur hunting Malagasy Crowned Eagles that lived on Madagascar until the 16th century. However reports from other travellers of massive eggs, which belonged to Aepyornis, became associated with the Roc, and so the Aepyornithae family became collectively known as “Elephant Birds”. The Aepyornithae belonged to a larger order of birds known as the Ratites. This is the same group that contains ostriches, emus and cassowaries. You may think that since the Elephant Birds lived on Madagascar their closest relatives would be African ostriches since Madagascar lies off the East African coast. However this is not the case. Their closest living relatives are actually kiwis; small flightless birds which have long, thin beaks, reduced eyesight and are also ratites. Kiwis live only on New Zealand, which is 7,000 miles east of Madagascar! So how are these two birds so closely related despite living so far apart? Well the theory is that around 60 million years ago the common ancestor of kiwi’s and Elephant Birds still possessed flight and flew to these two separate islands, establishing colonies. Then, over millions of years, the two islands drifted further apart from each other (out of flying range) and the two separated populations both evolved flightlessness, independently of one another.

Another result of living on an isolated island for much of their evolution, and with no large mammalian herbivores to compete with, is that the Elephant Birds could grow to massive sizes. Aepyornis was no different and was thought to have been the largest bird that ever lived until relatively recently. Originally it was believed that Aepyornis maximus could grow to heights of more than 3 metres and weigh up to 800kg. However a study in 2018 by Hansford & Turney showed that there were enough skeletal differences between these largest specimens and other Aepyornis for these large Aepyornis to be re-classified as a new member of the Aepyornithae family (alongside Aepyornis and another Elephant Bird named Mullerornis). It was given the rather striking name of Vorombe titan, which is a combination of Malagasy and Greek and translates to “big bird” (Vorombe = Malagasy for bird, titan = Greek for big). As a result the size estimates of Aepyornis is now considered to be a more modest 2.5 metres tall and 400-500kg in weight on average, which is still larger than any living bird! Another of Aepyornis’ (and other Elephant Birds’) claims to fame is their humongous eggs. At their biggest they measured 34cm long, had a circumference of a metre and weighed 15 kilos. That’s 150 times bigger than a chicken egg, larger than any dinosaur egg and the largest eggs of any animal ever. Imagine the fried egg you would get from that! It wouldn’t just be enough for your breakfast; it would be enough to feed your entire family for the whole day! Such huge eggs would have meant that Elephant Bird chicks would have been more highly developed compared to other birds and the lack of any large egg thieves (before humans arrived) meant that it would have been safer for Elephant Birds to lay these eggs.

An Aepyornis egg (the large one!) from Museo Capellini in Bologna, Italy.
Image Credit: Ghedoghedo, https://commons.m.wikimedia.org/wiki/File:Aepyornis_egg.JPG

Aepyornis held the ecological niche of “large herbivore” on Madagascar. Its diet consisted of fruit, grasses and leaves and Aepyornis used its strong neck and overall size to reach them, before biting off and swallowing chunks with its beak. Unlike a lot of other large herbivores recent research has suggested that Aepyornis was a mostly nocturnal animal. The evidence comes from another 2018 study (by Torres & Clarke) where Aepyornis braincases were examined with a CT scanner. This produced a 3D model that the researchers could manipulate and examine in detail. Using this they discovered that Aepyornis had enhanced olfactory lobes (the part of the brain that processes smells) and reduced optic lobes (the part of the brain that processes vision). This is a similar, albeit less extreme, version of the brain structure of kiwis; which are nocturnal birds with limited vision and a reliance on smell to sense their environment. Furthermore Torres & Clarke also showed that different Aepyornis species had slightly different sensory lobes. You see there are two recognised species of Aepyornis; Aepyornis maximus (the larger, forest dwelling one) and Aepyornis hildebranti (the smaller, plains dwelling one). In A.maximus the olfactory lobes were proportionally larger, and the optic lobes proportionally smaller, than in A.hildebranti. This is presumably because A.maximus lived in dense rainforests, where eyesight is less useful due to the dense trees, while A.hildebranti lived in the open plains where the lack of dense trees meant they could see greater distances.

Aepyornis shared its Madagascan home with a menagerie of recognisable animals still alive today, such as Ring-tailed lemurs, Fossas and Chameleons. However it also lived alongside some strange animals that are no longer around. These included Archaeoindris, a giant lemur that was the size of a Silverback gorilla, the aforementioned Malagasy crowned eagle which modern lemurs still possess an innate fear of even though it is now extinct, and giant tortoises similar in size and lifestyle to the modern day Galapagos giant tortoise. So once upon a time Madagascar had an even greater diversity of life than it does now. However there are no Elephant Birds, giant lemurs, huge tortoises or giant eagles anymore. This is thought to have been mainly due to change in climate, which lead to changes in food availability. The actions of humans are also commonly linked to the disappearance of many Madagascan animals. However they may not have played as big of a role as previously thought. Yet another 2018 study (2018 should be renamed “Year of the Elephant Bird” due to all the studies carried out that year!) dated Elephant Bird bones that showed distinctive cut marks made by human tools to 10,500 years ago, the end of the Pleistocene period and start of the Holocene period. This was a whole 8,000 years earlier than humans had previously been thought to have reached Madagascar. Since Aepyornis and other Elephant Birds became extinct sometime between the 10th-12th Centuries (though sightings had been reported to as late as the 17th century) this means that humans co-existed with the birds for longer than previously thought. So they couldn’t have quickly hunted them to extinction as had been previously assumed. However this doesn’t mean that Aepyornis wasn’t a target for humans or that human activity wouldn’t have affected their numbers. For one the sheer size of both the animal and especially its eggs (which could be quickly poached from Aepyornis nests) would have been an attractive prospect for human hunters. For another humans were converting the Madagascan forests and plains into farmland, destroying Aepyornis’ habitat, and domesticated chickens and guinea fowl brought to Madagascar may have passed on bird related diseases to Aepyornis, which it had no immunity to.

Aepyornis skull from a skeleton at the Muséum national d’Histoire naturelle in Paris, France
Image Credit: LadyofHats, https://zh.m.wikipedia.org/wiki/File:Aepyornis_skull.JPG

So overall, Aepyornis was a truly splendid animal, with a much more varied and detailed history and lifestyle than at first glance. The Elephant Birds are reminiscent of a time 65 million years ago when the close relatives of birds ruled the world. The dinosaurs were long gone, but in this little corner of the world Aepyornis and its family carried on their legacy.

References/Further Reading

Torres & Clarke 2018: a study of the braincases of the Elephant Bird, and what it tells us about their noctournalism

Christopher R. Torres and Julia A. Clarke 2018, Nocturnal giants: evolution of the sensory ecology in elephant birds and other palaeognaths inferred from digital brain reconstructions, Proc. R. Soc. B.28520181540, http://doi.org/10.1098/rspb.2018.1540

Hansford & Turney 2018: a study on the diversity of the Elephant Bird (Aepyornithae) family, showing that the largest Aepyornis were actually a different species of Elephant Bird: Vorombe Titan

James P. Hansford and Samuel T. Turvey 2018, Unexpected diversity within the extinct elephant birds (Aves: Aepyornithidae) and a new identity for the world’s largest bird, R. Soc. open sci.5181295, http://doi.org/10.1098/rsos.181295

Hansford et. al. 2018: a study on Elephant Bird bones with human made cut marks dating from as far back as 10,500 years ago

James Hansford, Patricia C. Wright, Armand Rasoamiaramanana, Ventura R. Pérez, Laurie R. Godfrey, David Errickson, Tim Thompson, Samuel T. Turvey. Early Holocene human presence in Madagascar evidenced by exploitation of avian megafauna. Science Advances, 2018; 4 (9): eaat6925 DOI: 10.1126/sciadv.aat6925

An American Museum of Natural History page about the association of the Roc and Aepyornis, part of their “Mythic Creatures” exhibition

“Strike from the Sky”, Mythic Creatures Exhibition, American Museum of Natural History, https://www.amnh.org/exhibitions/mythic-creatures/air/strike-from-the-sky

A Smithsonian magazine article about the giant eggs of the Elephant Birds

Katz, Bridget, “Giant, Intact Egg of the Extinct Elephant Bird Found in Buffalo Museum”, Smithsonian Magazine, April 23rd, 2018, https://www.smithsonianmag.com/smart-news/giant-intact-egg-extinct-elephant-bird-found-buffalo-museum-180968850/

Bolton, Houston & Monaghan 1992: A study on the link between large eggs and survivability of baby birds

Bolton, M., Houston, D., & Monaghan, P. (1992). Nutritional Constraints on Egg Formation in the Lesser Black-Backed Gull: An Experimental Study. Journal of Animal Ecology, 61(3), 521-532. doi:10.2307/5607

Basilosaurus: The Tale of King Basil

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A Reconstruction of how Basilosaurus (and the one and only King Basil) would have looked!
Image Credit: Dmitry Bogdanov, https://commons.wikimedia.org/wiki/File:Basilosaurus1DB.jpg

35 Million years ago during the Late Eocene period, in a shallow sea that would one day become the Sahara Desert, a king ruled the waters. His name was Basil, he was 20 years old and one of the largest of his kind. He has reached this age in large part because of the excellent early parental care of his mother, a key trait of mammals like him. He was taught how to navigate, to hunt and his mother used every ounce of her might to protect him from danger. Now he is in his prime, has fathered many offspring and has his pick of food that sustains his enormous appetite. Life is good for the king and there is nothing that can threaten him……for now.

Basil is a Basilosaurus, a name meaning “King Lizard” in Latin. However Basil and his kind are far from lizards! They are part of what was at the time a relatively new group of sea faring animals; the whales. Two species of Basilosaurus have been discovered. The first is Basilosaurus cetoides, which ranged from the coast of what is now Alabama and New Mexico in the USA to Egypt. The second is Basilosaurus isis, which swam in waters covering much of Morocco and Egypt. Combining the localities of these two species we can see that Basilosaurus had a wide geographical distribution, stretching across almost half the globe. Along this distribution both Basilosaurus species are thought to have resided in coastal and shallow water regions rather than the deep ocean; a slightly unusual habitat considering their huge size. Furthermore both Basilosaurus species lived in an ocean which no longer exists! This ocean was known as the Tethys, a once mighty watery expanse that linked the Indian and Atlantic Ocean. During the Late Eocene period it covered where much of Arabia, North Africa and the Mediterranean Sea area are now. The Tethys would eventually disappear around 23 million years ago but the coastal margins of this strange, primordial ocean was a place where Basilosaurus (and many other marine fauna) called home.

The fossilised skull of Basilosaurus isis (top) and Basilosaurus cetoides (bottom). Note the slight differences in teeth and skull shape between the two species.
Image Credit: Ghedoghedo, Ninjatacoshell, https://en.m.wikipedia.org/wiki/File:Basilosaurus_isis_and_cetoides_skulls_compared.png

The first Basilosaurus fossils were found in the 1830s. Rather curiously, when they were first unearthed, the large vertebrae were used as furniture! After this the fossils were initially studied by Richard Harlan, a Philadelphia based Naturalist, before being passed on to Sir Richard Owen, the famous British Naturalist who’s best known for coining the term “dinosaur” and for founding the Natural History Museum in London. Harlan at first thought that these bones belonged to a giant marine reptile, partly due to the animal’s unusually long body (like an actual sea serpent!) and superficially reptile-like skull. This is why it was given the name of Basilosaurus, or “King Lizard”. However later studies revealed Basilosaurus’ characteristic mammalian features. For example it was found to have heterodont dentition, which means they have teeth of various shapes each with their own function (in this case sharp incisors and flattened serrated molars). In contrast reptiles have homodont dentition, meaning their teeth are all the same shape and have the same function. Once he realised the mistake Sir Richard Owen suggested that this animal’s name should be changed to Zeuglodon; which means “Yoke Teeth” on account of their distinct shape. However this would have violated the golden rule of scientifically naming an organism; “The first name that is given is the one that is always used (unless the name is already in use or the new organism turns out to actually be one we’ve previously discovered and named)”. Therefore the name Basilosaurus stayed, resulting in the rather bizarre situation where a whale (which is a mammal) is called a lizard (which is a reptile). A great example of how palaeontology is full of weird names that sometimes don’t make sense!

A serpentine shape isn’t the only feature that differentiated Basilosaurus from modern whales. It also possessed small, stumpy and external hind limbs. While modern whales also possess hind limbs they are internal, hidden beneath the large layers of fat, muscle and skin. These tiny legs are remnants from a time (roughly 20 million years or so before Basilosaurus) when the ancestors of whales were small, four-legged hoofed mammals that were first dipping their toes back into water. Whereas these ancestors used their hind limbs for walking, Basilosaurus’ were way too small and stumpy for such a “feet” (sorry, couldn’t resist the pun). Instead it’s thought that the hind limbs were used to help lock and intertwine the long bodies of two Basilosaurus’ together during mating. Basilosaurus also lacked some characteristic anatomy that modern whales possess. This included a “melon” in their heads; a mass of tissue which modern whales use for echolocation. Furthermore Basilosaurus’ blowhole, which it used to take breaths at the surface, was positioned further forward (between the snout and top of its head) than in modern whales. As Basilosaurus preferred shallow water environments it is also thought that they didn’t dive to great depths (like Sperm Whales and Cuvier’s beaked whales do).

Mounted skeleton of Basilosaurus isis from the Museum d’Histoire Naturelle in Nantes, France
Image Credit: Asmoth, https://commons.m.wikimedia.org/wiki/File:Basilosaurus_isis_fossil,_Nantes_History_Museum_01.jpg

Basilosaurus was a giant of its time; measuring up to 20 metres long and weighing up to 20 tons. This meant that it was the undisputed top predator of the Late Eocene seas. The size of Basilosaurus varied between the two species; with B.cetoides measuring between 17-20 metres while B.Isis was between 15-18 metres. As you can see from this range in lengths there was also size variation between members of the same Basilosaurus species. One reason for this is that they exhibited sexual dimorphism. We know this because on average male Basilosaurus vertebrae measure 20% longer than in females of the same age. In terms of its lifestyle a modern day comparison to Basilosaurus might be the Orca (aka “The Killer Whale”). Both are large predatory whales that are top predators in their environments. Like Orcas, the diet of Basilosaurus consisted of fish (e.g. Pycnodus) and other marine mammals. One particular marine mammal that was on the menu was Dorudon atrox, a 5 metre long prehistoric whale which actually belonged to the same family as Basilosaurus; “The Basilosauridae” (guess what animal the family was named after). Fossils discovered in the last two decades have shown a direct predator-prey relationship between these two whales. Skulls of Dorudon have been found with bite marks that perfectly match the size and shape of Basilosaurus teeth. Furthermore these marks form a pattern on the Dorudon skull that indicate that the bite was across the head, a tactic that’s often used by predators to quickly immobilise and cripple their prey. In addition approximately 50% of these skulls were deduced to be of young Dorudon. This was due to the presence of deciduous (i.e. baby) teeth, while accompanying vertebrate had open growth plates which is the part of the bone that grows, before hardening when animal matures. This suggests that Basilosaurus targeted Dorudon “nursery groups” that consisted of young Dorudon and a few adults. It undoubtedly would have been a waking nightmare for the young Dorudon to see a large and hungry Basilosaurus burst into their nursery. But from the Basilosaurus’ perspective hunting the more vulnerable prey (e.g. young, old, injured and/or sick) gives them a greater chance of getting a vital meal, one that could prevent them from starving, and is a tactic employed by every predator from Lions, to Eagles, to Orcas.

King Basil eventually reached the end of his road as the years of swimming, hunting and fighting finally caught up to him. His latest wounds, sustained from a fight with a younger and faster male, are this time going to be fatal. As blood loss starts to take its toll Basil takes one last breath at the surface, before his body eventually gives out. The king has been dethroned. The younger male has long since swum off to start his own reign, but the line of succession will eventually end 33 million years ago. A drop in sea levels and a changing climate would push all Basilosaurus to extinction. As for Basil his body eventually sinks to the bottom of the sea and over time is picked clean by scavengers, buried by ocean sediment, and undergoes the fossilisation process that will turn his bones into hard rock. 35 million years later his bones will eventually resurface as another Basilosaurus fossil, with an intrepid palaeontologist meticulously dusting the sand of the Sahara Desert away to expose his remains. His final resting place is Wadi Al Hitan, a fossil site located 150km South-West of Cairo in Egypt. This place is also known as the “Valley of the Whales”. This is fitting, as just like the Egyptian pharaohs buried in the “Valley of the Kings”, Basil was a monarch among his own kind.

References/Further Reading

Fahlke 2012 paper that further examined the bite marks on Dorudon skulls, reinforcing the hypothesis that they match the teeth of Basilosaurus and that Basilosaurus actively hunted Dorudon

Fahlke, J. M. (2012). Bite marks revisited—evidence for middle-to-late Eocene Basilosaurus isis predation on Dorudon atrox (both Cetacea, Basilosauridae). Palaeontologia Electronica, 15(3), 32A.

Voss et. al. 2019 paper describing the preserved stomach contents of a Basilosaurus isis fossil

Voss M, Antar MSM, Zalmout IS, Gingerich PD (2019) Stomach contents of the archaeocete Basilosaurus isis: Apex predator in oceans of the late Eocene. PLoS ONE 14(1): e0209021. https://doi.org/10.1371/journal.pone.0209021

Uhen 2004 paper that first described the bite marks on Dorudon skulls and suggested that they were due to Basilosaurus predation

Uhen MD. Form, function, and anatomy of Dorudon atrox (Mammalia, Cetacea): an archaeocete from the middle to late Eocene of Egypt. University of Michigan Papers on Paleontology. 2004; 34: 1–222.

Fossilworks database on Basilosaurus species, synonyms and papers related to it

Fossilworks, “Basilosaurus Harlan 1834 (whale)”, Fossilworks, http://fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=36681

The New York Institute of Technology College of Osteopathic Medicine (try saying that five times fast!) page describing Basilosaurus (written by Robert Boessenecker and Jonathan Geisler)

Boessenecker, Robert, Geisler, Jonathan, “Basilosaurus spp.”, College of Osteopathic Medicine, The New York Institute of Technology, https://www.nyit.edu/medicine/basilosaurus_spp#

A Comparative Anatomy website page, from the University of the Cumberlands, giving an overview of Heterodont and Homodont Dentition

Comparative Anatomy, “The Teeth of Vertebrate Animals”, Comparative Anatomy, https://inside.ucumberlands.edu/academics/biology/faculty/kuss/courses/Digestive%20system/TeethOf%20Vertebrates.htm

“All hail the Great Beast Megatherium!”

File:Megatherium NT small.jpg - Wikimedia Commons
A reconstruction of the Great Beast
Image Credit: Nobu Tamura, (© N. Tamura), http://spinops.blogspot.com/2015/02/megatherium-americanum.html

“Deluded! Madman! Fake Scientist!”

The Cryptozoologist had been called these a lot throughout his professional career, (as well as other, more mean things). Time after time after time he had failed to discover any of the amazing creatures’ people claimed to have seen, with the majority being proven to never have existed in the first place. Now, nearing his retirement, he was wandering the amazon rainforest looking for yet another cryptid; the “Mapinguari”. “Just turn around” the voice in his head said (not for the first time). “They’re just stories made up to attract tourists or hoaxers trying to make a name for themselves or misidentified animals. None of them are real!”. The Cryptozoologist sighed, and for the first time in his life he wondered “Maybe I am a crazy old man”. Then he heard it, a crash of vegetation coming from the trees just to the left of him. He turned round, straining to locate exactly where the noise had come from. Then he saw it, and his jaw dropped. What he was seeing was an animal believed to have gone extinct 8,000 years ago. It was a great beast taller than an elephant and just as bulky, which possessed huge claws that it was currently using to pull down branches from a nearby tree towards its mouth. As he took out his camera and frantically took pictures two more large adults shuffled out of the forest, one of which had a baby clinging onto to its back. “They wouldn’t believe me” the Cryptozoologist thought. “But just wait till they see you!”

This “Great Beast” is known scientifically as Megatherium Americanum (meaning “Great Beast from the Americas”). Megatherium is an animal that palaeontologists have known about for a very long time. The first fossils were discovered in 1787, four decades before the first dinosaurs would be found, in Argentina by a man named Manuel Torres. After their discovery these bones were shipped to the Museo Nacional de Ciencias in Madrid, Spain, where they still reside today (another reason to visit Spain!). It was from these bones that French naturalist Georges Cuvier first described and named Megatherium, noting its close relation to modern day tree sloths. After these first fossils more were discovered, including bones found by Charles Darwin from 1832-1833 during the first Beagle expedition. Even nowadays new discoveries are revealing more insights. For example a paper published in 2017 (by Bocherens et. al.) looked at preserved collagen proteins in Megatherium fossils to give insights into its diet. Some people have gone a step further and claimed that Megatherium is still alive somewhere in South America. Stories from Brazil tell of the “Mapinguari” or “sloth monster”; a shaman who was transformed by the gods into a giant sloth-like creature. Cryptozoologists (like the one in the story) think the Mapinguari is actually a late surviving species of Megatherium, however scientists (and yours truly) don’t take these stories seriously due to absence of any concrete evidence.

A mounted skeleton of Megatherium with a awe inspired human for scale!
Image Credit: Beatrice Murch, https://www.flickr.com/photos/blmurch/3495336846

Megatherium belonged to a large order (or “superorder”) of mammals known as the xenarthans. Modern xenarthans include Tree Sloths, Anteaters & Armadillos, but during the Cenozoic era this group was much more diverse. From their origins in South America they ended up colonising North America, grew to a range of shapes and sizes and occupied a wide variety of habitats ranging from the treetops (e.g. modern tree sloths) to even the ocean (e.g. the swimming ground sloth Thalassocnus). Megatherium itself belonged to a sub-order of xenarthans commonly known as the “Giant Ground Sloths”. These sloths were very different from their slow moving and tree dwelling modern counterparts. They were bulky, ground living herbivores with large and sharp claws. While Megatherium itself was confined to South America other species of Giant Ground Sloths migrated across the Isthmus of Panama into Central and North America. This was during the great American interchange; a time where multiple species from South America migrated into North America (and vice-versa). As a result Giant Ground Sloths established populations in places such as Costa Rica, Texas and California.

Because multiple fossils of the “Great Beast” have been known to palaeontologists for some time we have a pretty good idea of what it would have been like. Megatherium roamed the South American pampas, mostly in Argentina, Bolivia and Uruguay, from the Pleistocene (roughly 400,000 years ago) to Early Holocene (roughly 8,000 years ago) periods of the Cenozoic era (a timespan commonly known as the “Ice Age”). This beast stood over 3.5 metres tall when fully upright and weighed up to 4 tonnes, making it the largest animal in South America during the Ice Age and the largest xenarthan ever. Its potbellied frame was supported by column-like hind legs that would have given it a long reach. Furthermore preserved Megatherium track-ways and its skeletal anatomy indicate that it could have walked on two legs as well as on all fours. Its front limbs were tipped with large, non-retractable claws which were used for pulling branches closer to them to eat and for digging up roots and tubers. In fact the claws were a reason that Megatherium was initially thought to have been a burrower, living like giant mole! Big claws would have undoubtedly been very effective defensive weapons with Megatherium using them, alongside its large size, to protect itself from predators, such as the large Sabre-Tooth Cat Smilodon populator. Other distinctive features include a relatively narrow snout, a prehensile upper lip (like a black rhino) and a thick shaggy coat. This coat is found on most Megatherium reconstructions and is based on the discovery of exceptionally preserved hair and hide specimens of related Giant Ground Sloths. However a study from 2002 (Fariña 2002) has speculated that Megatherium might’ve been nearly hairless! This is based on the observation that modern large mammals, such as elephants and rhinos, are mostly hairless to prevent them from overheating in hot climates (large animals produce a lot more excess heat). Megatherium may seem very different to what we would think of a typical large herbivore today. However the overall body plan of a large, bulky, bipedal herbivore with large claws has actually appeared a few times throughout earth’s history. One example is the Therizinosaur dinosaurs; a group which lived a full 65 million years earlier than Megatherium but is thought to have lived a similar lifestyle. This is an example of convergent evolution; where two completely unrelated organisms, often separated by millions of years of evolution, evolve similar body plans to live in similar ways. It’s a very fascinating phenomenon that has resulted in a lot of symmetry between modern and extinct animals (e.g. Dolphins and Ichthyosaurs).

A Megatherium looking at the horizon as two glyptodonts waddle by!
Image Credit: D. Bogdanov (DiBgd), https://commons.m.wikimedia.org/wiki/File:Pleistocene_SA.jpg#mw-jump-to-license

Such a majestic animal is another example how diverse the megafauna were during the last Ice Age. However the majority of these animals are not around anymore. Megatherium’s story is similar to other megafauna. Climate change at the end of the last Ice Age played a part, resulting in a loss of habitat and decline in population. This was combined with the arrival of modern humans into South America roughly 14,500 years ago. Some Megatherium bones bear distinct marks on them that indicate that they were cut by human tools. Furthermore other bones have been unearthed alongside human made stone tools and weapons. Tools, high intelligence and co-operation made humans a terrifying predator for a Megatherium to try and defend itself against and humans were so efficient that Megatherium numbers dwindled further. Eventually the dynasty of the Great Beast would come to a close 8,000 years ago. This unfortunate end makes one wish that the Cryptozoologists were right, and that Megatherium was somehow still living in South America to this day. If this were the case then I’m sure many more people would see what a “Great Beast” it really was.

References/Further Reading

Bocherens et. al. 2017 paper reconstructing the diet of Megatherium from analysis of collagen in the fossils

Bocherens et. al. (2017), Isotopic insight on paleodiet of extinct Pleistocene megafaunal Xenarthrans from Argentina. Gondwana Research, 2017; 48: 7 DOI: 10.1016/j.gr.2017.04.003

Billet et. al. 1997 paper examining the inner ear anatomy of Megatherium and what it tells us about its body mass and agility

Billet, G et al. “The inner ear of Megatherium and the evolution of the vestibular system in sloths.” Journal of anatomy vol. 223,6 (2013): 557-67. doi:10.1111/joa.12114

Natural History Museum website article profiling Megatherium and detailing a project that was digitally scanning all the fossils Charles Darwin collected on the 1831-1836 Beagle voyage

Brewer, Pip, “What was Megatherium?”, Natural History Museum, https://www.nhm.ac.uk/discover/what-was-megatherium.html

Fariña 2002 paper suggesting that the largest Giant Ground Sloths, such as Megatherium, were mostly hairless

Fariña, Richard. (2002). Megatherium, the hairless: appearance of the great Quaternary sloths (Mammalia;Xenarthra). AMEGHINIANA. 39. 241-244.

Politis et. al. 2019 paper, published in Sciences Advances, on the discovery of Megatherium remains that show evidence of Human Hunting

Politis, Gustavo & Messineo, Pablo & Stafford Jr, Thomas & Lindsey, Emily. (2019). Campo Laborde: A Late Pleistocene giant ground sloth kill and butchering site in the Pampas. Science Advances. 5. eaau4546. 10.1126/sciadv.aau4546.

Acanthostega: The shape of things to come

File:Acanthostega MLCS.JPG - Wikipedia
Acanthostega wondering what you’re looking at!
Image Credit: Conty, https://en.wikipedia.org/wiki/File:Acanthostega_MLCS.JPG

Throughout earth’s history there have been many major leaps in evolution; the evolution of eyes, the first multicellular animals and (from our point of view) the first time our hominid ancestors walked upright. However one that sticks out in a few people’s minds is when vertebrates first hauled themselves out of the water and started walking on land. To illustrate just how big this step was, imagine an alternate reality where it never happened. This parallel world would contain no reptiles, birds or mammals, and human civilisation would’ve never emerged. The vertebrates in this world are comprised of a wide variety of fish species swimming in seas, lakes and rivers across the world alongside a range of molluscs, crustaceans and corals (to name a few). On land the world is still covered in thousands of plant species but the only animals are invertebrates. Beetles, arachnids, and ants of all possible sizes scuttle along the ground. Dragonflies, wasps and flies buzz and dance through the air and worms bury through the soil keeping the ecosystem together. All in all, it is a world radically different to what we know.

As a result documenting how and why this important moment in life on earth occurred is key to understanding the world around us. One animal that has helped palaeontologists to do this is a 60 cm long stem-tetrapod that swam the rivers of Greenland during the Devonian Period (360 million years ago). Its name was Acanthostega gunnari, meaning “Gunnars spiny roof”.

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A model of a swimming Acanthostega
Image Credit: Dr. Günter Bechly, https://commons.wikimedia.org/wiki/File:Acanthostega_model.jpg

While fossils of Acanthostega were first discovered in 1933 (and described in 1952 by Gunnar Säve-Söderbergh, who the species is named after, and Erik Jarvik) the majority of what we know about it comes from a magnificent bone bed, part of the Celsius Bjerg Group rock sequence found in East Greenland, that was discovered in 1987 by a team led by Palaeontologist Jenny Clack. These beds contains the remains of multiple Acanthostega buried and preserved with their skeletons almost completely intact. A paper released in 2016 (Sanchez et. al. 2016) detailed another interesting observation about these fossils. Micro CT synchrotron scans of the interior of the arm bones showed that the bones were still reasonably cartilaginous and had yet to fully ossify (i.e. harden into fully formed bones). This ossification happens as animals mature, so it was deduced that all of the 1987 fossils were of juvenile Acanthostega (roughly around 6 years old) who seem to have been living together. The ossification process also seemed to have progressed further in some individuals than in others, suggesting that there was size variation between members of the group, either through genetic variation, sexual dimorphism or even both. Tragically for this ragtag group of youngsters, it seems that they all died together. It is thought that a flash flood might have washed all of them into a small pool of water. This then dried up after the flood receded leaving them stranded and exposed to the elements, away from the water that kept their skin from drying out.

Acanthostega is a great example of a transitional fossil. Its anatomy is comprised of both basal fish-like features (e.g. internal gills, fish-like teeth, fleshy tail fins and a lateral line system) and derived tetrapod-like features (e.g. simple lungs and limbs tipped with digits). Curiously all these features would have made Acanthostega perfectly suited for its river home. It used its fleshy tail to power itself through its river home, snapping at any fish that wondered too close, and to help locate its prey and navigate through its watery environment it used a lateral line system to sense movement and pressure gradient changes. These features (along with its internal gills) meant it stayed underwater for long stretches of time, though its simple lungs enabled it to take breathes of air if required. What surprised palaeontologists the most about Acanthostega was the structure and function of its limbs and the number of digits on each limb. The limbs were not large or robust enough to bear Acanthostega’s weight for long, meaning it would only rarely spend time on land (if at all). Instead the limbs acted as paddles, aiding with swimming and manoeuvring underwater. This is important because it showed that the early tetrapods didn’t evolve limbs when they started walking on land, but instead first evolved them to better aid them underwater. Then later in time they would adapt this pre-existing feature to use for walking on land. The story is the same for its digits. Each of Acanthostega’s limbs were tipped with 8 digits. This showed that the number of digits on stem-tetrapod limbs wasn’t restricted to a set number (originally thought to have been 5). These early digits would have had webbed and made the early limb a more effective paddle. Then later in evolutionary time digits (like limbs) evolved to help bear and spread out the vertebrate’s weight when it was on land.

File:Acanthostega gunnari.jpg - Wikimedia Commons
A skeletal of reconstruction of Acanthostega. Note its 8 digits, flat skull and paddle-tail.
Image Credit: Ryan Somma, https://commons.wikimedia.org/wiki/File:Acanthostega_gunnari.jpg

Looking at all of its features its certain that Acanthostega would have actually spent almost all of its time in water, patrolling the waterways and hunting for small fish and arthropods. Its fish like skull features and relatively weak bite force (adapted more for gripping prey) compared to later tetrapods were perfectly adapted for catching slippery aquatic prey, meaning it didn’t hunt terrestrial animals. Like modern day amphibians Acanthostega would have laid its eggs in water as the eggs lacked a hard watertight casing. Throughout its life Acanthostega would also have had to watch its back! Multiple species of large freshwater fish were alive during the Late Devonian and many of them would have seen Acanthostega as a tasty meal.

So while Acanthostega wouldn’t have been much of a “land lubber”, it was a shape of things to come. This small river dweller helped palaeontologists to figure out the early evolutionary history of the stem-tetrapods and showed that limbs and digits, those features that you use every day, were first developed for underwater use, and only later on evolved for use on land.

All that we know about Acanthostega, the evolution of limbs and digits and how vertebrates first ventured out of the water, couldn’t have been possible without the hard work and dedication of Jenny Clack. Before her work this evolutionary transition period wasn’t particularly well understood. However her meticulous research on every facet of Acanthostega (whose fossils she sometimes gave nicknames to, such as “Boris”, “Rosie” and “Grace”) and its relatives, revolutionised our understanding of this key period of vertebrate evolution. She was one of the world’s leading experts on stem-tetrapods and Acanthostega in particular. This is clear to see as almost every scientific paper released about Acanthostega over the last three decades has carried her name either as a researcher or as a source. Sadly Jenny Clack passed away in March of this year (at time of writing). She will be greatly missed by her friends, family and the wider scientific community. With her passing, the world has lost one of the great palaeontologists.

References/Further Reading

Sanchez et. al. 2016 paper detailing the growth and life history of Acanthostega

Sanchez, S., Tafforeau, P., Clack, J. et al. Life history of the stem tetrapod Acanthostega revealed by synchrotron microtomography. Nature 537, 408–411 (2016). https://doi.org/10.1038/nature19354

Clack 2002 paper on the skull roof of Acanthostega

Clack, J. (2002). The dermal skull roof of Acanthostega gunnari, an early tetrapod from the Late Devonian. Transactions of the Royal Society of Edinburgh: Earth Sciences, 93(1), 17-33. doi:10.1017/S0263593300000304

Neenan et. al. 2014 paper on the feeding biomechanics of Acanthostega

James M. Neenan, Marcello Ruta, Jennifer A. Clack and Emily J. Rayfield (2014) Feeding biomechanics in Acanthostega and across the fish–tetrapod transition, Proc. R. Soc. B.28120132689, https://doi.org/10.1098/rspb.2013.2689

Porro, Rayfield & Clack 2015 paper on a 3d reconstruction of an Acanthostega skull. This allowed the trio to infer how Acanthostega caught prey.

Porro, Laura B et al. (2015) “Descriptive anatomy and three-dimensional reconstruction of the skull of the early tetrapod Acanthostega gunnari Jarvik, 1952.” PloS one vol. 10,3 e0118882, doi:10.1371/journal.pone.0118882

Tree of Life web project section on Acanthostega, written by the Late Jenny Clack

Clack, Jennifer A. 2006. Acanthostega. Acanthostega gunnari. Version 13 June 2006. http://tolweb.org/Acanthostega_gunnari/15016/2006.06.13 in The Tree of Life Web Project, http://tolweb.org/

Another Tree of Life project section written by Jenny Clack on the definition of “Tetrapod” and how it is debated

Clack, Jennifer A. 1997. The Definition of the Taxon Tetrapoda, 1997, http://tolweb.org/accessory/Definition_of_the_Taxon_Tetrapoda?acc_id=471 in The Tree of Life Web Project, http://tolweb.org/

The University of Cambridge Department of Zoology news article on the passing of Professor Jenny Clack

Aucott, Rachael, “Professor Jenny Clack, FRS, 1947-2020”, University of Cambridge, 26th March, 2020, https://www.zoo.cam.ac.uk/news/professor-jenny-clack-frs-1947-2020

A Science Direct web page about lateral line systems

Science Direct, “Lateral Line System”, Science Direct, https://www.sciencedirect.com/topics/medicine-and-dentistry/lateral-line-system

Clack & Neininger 2000 paper on the Celsius Bjerg Group, a rock sequence that Acanthostega fossils have been found in

Clack, J. A. and S. L. Neininger (2000). “Fossils from the Celsius Bjerg Group, Late Devonian sequence, East Greenland; significance and sedimentological distribution.” Geological Society, London, Special Publications 180(1): 557-566.

Daeodon the Terminator

How the Terminator Pig is thought to have looked like!
Image Credit: Max Bellomio, https://commons.m.wikimedia.org/wiki/File:Daeodon_shoshonensis_.png

Daeodon is an animal that has had a lot of rather intimidating nicknames associated with it over the years. These have ranged from the “Terminator Pig” (which makes me think of a pig wearing sunglasses and travelling through time on a mission to destroy!) to the “Hell Pig” (which suggests a giant boar rising from a fiery pit accompanied by heavy metal!). Even its name “Daeodon” translates as “Dreadful Teeth”, a name that would strike fear into the hearts of dentists everywhere. But what was Daeodon really like? And did it deserve its reputation?

Daeodon belonged to a now extinct branch of the “artiodactyls”, a mammal group that also contains pigs, horses and even whales, known as the Entelodontidae, or “Entelodonts”. In life Entelodonts would have looked superficially pig-like with a long snout, hooved feet, tall shoulder hump, short tail and a round body. The “terminator” and “hell” parts of its nicknames stem from its huge size, Daeodon was the size of a bison, and it’s grotesque looking face which possessed side flanges, bony bumps and fearsome looking teeth. However despite appearances the Entelodonts’ closest relatives are not actually pigs. A study published in 2009 by Michael Spaulding, Maureen O’Leary and John Gatesy found that, whilst studying the ancestry of the artiodactyl group, they were more closely related to the whippomorpha subgroup (which contains hippos, whales and dolphins) than modern pigs. This has changed some reconstructions of entelodonts into a more bulky animal than previously thought, more akin to a land-based hippo than an oversized pig. So maybe the famous nickname of “terminator pig” should now be “terminator hippo”, which is just as horrifying considering how aggressive and dangerous modern hippos are! Entelodonts were a very successful group of mammals. First evolving in Mongolia roughly 40 million years ago during the Eocene they diversified into multiple different species that spread into Europe and North America during the Oligocene and Miocene. Daeodon was in many ways the culmination of this line, being not only the largest entelodont but also one of the last.

The skull of Daeodon showing its strong build and differentiated teeth.
Image Credit: Matt Celeskey, https://commons.m.wikimedia.org/wiki/File:Daeodon_skull.jpg

Roaming the plains of North America from 25-18 million years ago, Daeodon lived alongside a weird menagerie of life consisting of animals both familiar and unfamiliar. Alongside the ancestors of today’s horses and camels were extinct animals like the Chalicotheres, relatives of horses that walked on their knuckles like gorillas and possessed large claws that they used to pull down vegetation, and Hyaenodonts, mammalian carnivores that belonged to the now extinct Creodont group. Standing 1.8 metres tall and weighing roughly half a tonne Daeodon would have been an imposing animal in this environment. The distinctive flanges on its 3 ft. long head covered large cheek bones and were anchor points for large jaw and neck muscles, giving it a very powerful bite. Despite its fearsome appearance however, Daeodon was an omnivore. It possessed differentiated teeth just like in humans; gripping incisors at the front, large canines in the middle and crushing molars at the back. This enabled it to eat almost anything it came across including roots and tubers, fruit, leaves and meat. It would have been a very effective scavenger as a highly developed sense of smell would allow it to locate a carcass accurately from a distance, tracking the smell in a zig-zagging fashion. Furthermore its large size would have enabled it to drive off other animals from the kill. Make no mistake however, Daeodon would have dabbled with hunting live prey as well. It is thought to have been an ambush hunter, using its large size and powerful jaws to overpower and crunch through prey. But it’s not just other animals that Daeodon would have fought. Puncture marks found on the skulls of other entelodont species have shown that they fought each other, whether for mates, territory or both. So in many ways, given its large size and omnivorous lifestyle, Daeodon might have had a similar lifestyle to a modern day Grizzly Bear. Sadly this magnificent beast isn’t around today to give Grizzly Bears a contest. The last Daeodon went extinct around 18 million years ago. This coincided with the first emergence in North America of the large Bear-Dog Amphicyon (see my Amphicyon blog for more!), which had migrated from Asia. This predator, while smaller, was swifter and most importantly; more intelligent. As a result it seems to have partly out-competed Daeodon. Combining this with a climate which was becoming drier as the Miocene progressed resulted in Daeodon being driven to extinction, leaving only their fossils as remnants of a once widespread group.

Speaking of these fossils, the first Daeodon fossils were discovered in 1879 by the American fossil collector Edward Drinker Cope. Cope is a big name in the field of palaeontology, being responsible for the discovery of many extinct species such as the sauropod dinosaur Camarasaurus and the sail backed stem-mammal Dimetrodon. He is also known for his bitter rivalry with fellow American fossil hunter Othniel Charles Marsh. The two were locked in a race to discover and describe the most new species in a rivalry that has been termed “The Bone Wars”. When Cope examined Daeodon he determined it to be a member of the perissiodactyls, a group of mammals that contain modern day Zebras and Rhinos. It was only in 1909 when it was found that this wasn’t the case and it was actually an artiodactyl. For a long time Daeodon wasn’t the most widely known entelodont, with Dinohyus (meaning “terrible pig”) taking that title. However later it was found that Dinohyus and Daeodon, and another entelodont named Ammodon were actually one and the same animal. Because the rules of species dictate that the first name given to a species is the one that is kept Daeodon was the winner out of the three, with Dinohyus and Ammodon becoming synonyms.

A skeletal of Daeodon, showing how the bones all fit together and how big the animal was compared to a human.
Image Credit: bLAZZE92, https://blazze92.deviantart.com/art/Daeodon-shoshonensis-419367474

Entelodonts were a bizarre group of mammals, with Daeodon being the most eye-catching and iconic of them all. It dominated the North American landscape and while its size and power certainly earns it the “Terminator Pig” nickname (minus the pig part of course) that was only one side to it. As well as being a big and intimidating hunter and fighting for what it wanted, Daeodon would have eaten its greens, rolled happily in the mud and napped peacefully in the sun!

References/Further Reading

Spaulding, O’Leary and Gatesy 2009 paper on the family tree of artiodactyls, including who Entelodonts are most closely related to

Spaulding, Michelle et al. “Relationships of Cetacea (Artiodactyla) among mammals: increased taxon sampling alters interpretations of key fossils and character evolution.” PloS one vol. 4,9 e7062. 23 Sep. 2009, doi:10.1371/journal.pone.0007062

Joeckel 1990 paper on entelodont paleoecology and jaw function

Joeckel, R. (1990). A functional interpretation of the masticatory system and paleoecology of entelodonts. Paleobiology, 16(4), 459-482. doi:10.1017/S0094837300010198

A blog, written by Joe Sawchak and published on the Carnegie Museum of Natural History website, about a life size model of Dinohyus named “hyus”. This model was characterised by the weirdly human eyes!

Sawchak, Joe, “Dinohyus: “Terrible Pig” in more ways than one”, Carnegie Museum of Natural History, carnegiemnh.org/dinohyus-terrible-pig-in-more-ways-than-one/

An article, written by Vasika Udurawane and published on Earth Archives, about the rise of the “Terminator Pigs”

Udurawane, Vasika, “Terminator pigs: Rise of the entelodonts”, Earth Archives, 2016, eartharchives.org/articles/terminator-pigs-rise-of-the-entelodonts/

Yutyrannus: The Feathered Tyrant

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Reconstruction of Yutyrannus huali, Feathers and all!
Image Credit: Tomopteryx, https://commons.wikimedia.org/wiki/File:Yutyrannus_huali.png

Tyrannosaurs are arguably the most famous members of the great dinosaur pantheon. Their traditional look has been set in stone in the public eye for decades, being immortalised in various media, of a giant scaly lizard with tiny arms and a massive head full of sharp, banana shaped teeth. However what if I were to tell you that this picture isn’t completely accurate, and that at least some tyrannosaurs were in fact a lot more on the soft and fluffy side! While it’s still being debated to this day whether the mighty Tyrannosaurus Rex had feathers (a story for another blog!), there was another tyrannosaur that not only possessed feathers, but was completely covered in them! Revealed to the world in 2012 Yutyrannus huali (meaning “Beautiful Feathered Tyrant” in a mix of Mandarin and Latin) shaked pre-existing ideas about Tyrannosaurs to the core.

Yutyrannus was discovered in the Yixian formation, in the Liaoning Province of China by a Chinese palaeontologist named professor Xing Xu. This particular corner of the world is extremely rich in dinosaur fossils, mostly dating to the Early Cretaceous period (125 million years ago). A large majority of the feathered dinosaur finds in the last few decades originated from this area. Xu is a big name in the world of contemporary palaeontology as described and named a lot of these feathered dinos, such as the “four winged” Microraptor and another feathered tyrannosaur called Dilong. The Yutyrannus fossils discovered by Xu and his team consisted of an adult and two juveniles, all of them almost complete. This is remarkable as tyrannosaurs are often only known from incomplete fossils. So in this case we have a vividly detailed picture of this particular animal.

One of the most surprising observations about Yutyrannus is not only that it had feathers, but that this was a big animal. Previously other known feathered tyrannosaurs, such as Dilong and Guanlong (both also discovered in China), were relatively small; ranging around the sizes as modern big cats. However Yutyrannus bucked this trend by growing up to 9 metres long, 3 metres tall and weighing up to 1 and a half tonnes. This makes Yutyrannus the largest animal with direct definitive evidence of feathers ever discovered. While other dinosaurs like Therizinosaurus and Gigantoraptor are likely to have had feathers, there’s been no direct evidence found yet, so Yutyrannus keeps the crown for now. Unlike other large tyrannosaurs Yutyrannus shares many features with other early tyrannosaurs, such as possessing three fingers instead of two and a lack of a specialised weight-bearing middle toe (used by later tyrannosaurs to support their weight). By comparing its anatomy with other tyrannosaurs it was also deduced that Yutyrannus was not a direct ancestor to T-Rex, but instead belonged to a family of tyrannosaurs that split off during the Early Cretaceous, meaning that Yutyrannus was essentially T-Rexs great great uncle. Unlike later Tyrannosaurs Yutyrannus also possessed a small, midline crest at the end of its snout. This could have been used to attract a mate or to signal other individuals, saying for example “I’m the biggest and baddest of the Yutyrannus! Keep away!”. As the fossils were of an adult and two juveniles this could potentially be a family group. It has been theorised that tyrannosaurs may have lived in groups, so perhaps this find represents the sad end of a mum or dad raising its offspring.

Size comparison between a full grown Yutyrannus and a fully grown human. As you can see this was certainly a large feathered animal!
Image Credit: Conty, https://en.m.wikipedia.org/wiki/File:Yutyrannus_SIZE.png

The feathers themselves have been found preserved in patches across the whole body of all 3 fossils. In life they were relatively simple “proto-feathers”, consisting of long simple filament like structures. These filaments would have intertwined to produce a fluffy down; somewhere between the down on a baby chicken and the longer, fibrous feathers of an emu. The primary function is likely to have been to keep Yutyrannus warm. A study by Amiot et. al. in 2011 looked at oxygen isotope compositions found in reptile fossils from East Asia. These seem to indicate that at the place and time where Yutyrannus lived was a relatively cold, compared to the hothouse that was the rest of the Mesozoic, so a feathery coat would have helped to keep an active hunter like Yutyrannus at the right temperature. Other possible usages of this coat of feathers could have been to assist with attracting mates, as has been speculated to have been the case in other feathered dinosaurs (e.g. Caudipteryx), and any shed feathers could have been used to line their nests, as it is employed by modern birds. It has even been suggested that the colour of the feathered coat would have helped Yutyrannus camouflage itself against its surroundings, a trick that is employed by most predators today. Some reconstructions have given Yutyrannus a fully white coat to blend in with a snowy background (like a polar bear). While this is a neat bit of speculation, it can’t be proven until any melanosomes that may be preserved are examined. If so then palaeontologists would be able to discover the colour of a tyrannosaur for the first time!

An illustration showing a group of Yutyrannus hunting a juvenile Dongbeititan
Image Credit: PaleoEquii, https://commons.m.wikimedia.org/wiki/File:Dongbeititan_and_Yutyrannus.jpg

A lot of criticism of these feathered dinosaurs, and particularly with ideas about feathers existing on dinosaurs that were previously thought to be scaly, is that it makes dinosaurs “less cool looking” and more like giant turkeys. However I think that Yutyrannus is an excellent example of how feathers can enhance the interest in dinosaurs, providing another side to how we see these great lizards. An animal like this would certainly make a cute pet when it’s young. However, like pet owners who buy young tiger cubs, it’ll grow up over the years into a giant unmanageable carnivore, leaving the owner thinking “I REALLY didn’t think this through!”

References/Further Reading

Xu et. al. 2012 paper describing the 3 complete skeletons of Yutyrannus, including the description of its feathers

Xu, X., Wang, K., Zhang, K. et al. A gigantic feathered dinosaur from the Lower Cretaceous of China. Nature 484, 92–95 (2012). https://doi.org/10.1038/nature10906

American Museum of Natural History blog on getting to know Yutyrannus

AMNH, “Get to Know a Dino: Yutyrannus huali”, American Museum of Natural History, Apr. 11, 2016, amnh.org/explore/news-blogs/on-exhibit-posts/get-to-know-a-dino-yutyrannus-huali

Amiot et. al. 2011 paper on oxygen isotope compositions in fossils from the Early Cretaceous East Asia

Amiot, Romain et al. “Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates.” Proceedings of the National Academy of Sciences of the United States of America vol. 108,13 (2011): 5179-83. doi:10.1073/pnas.1011369108

A National Geographic article, written by Cliff Tarpy, about the fossils of Liaoning

Tarpy, Cliff, “Liaoning Province—China’s Extraordinary Fossil Site”, National Geographic, nationalgeographic.com/science/prehistoric-world/china-fossils/

Pentecopterus: The oldest Sea Scorpion yet

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A pair of Pentecopterus exploring together
Image Credit: Patrick Lynch, https://commons.wikimedia.org/wiki/File:Eurypterids_Pentecopterus_Horizontal.jpg

In the heart of London a famous food critic, sporting a sharp suit and meticulously polished shoes, sits down at a table. He’s about to review a wildly popular new restaurant, where the signature dish is “The Sea-Food Surprise“. After a disappointing starter that he could only describe as “tasting of old, dried rock” the Surprise arrives. To the critics astonishment the dish is absolutely splendid! Cooked to perfection in a piquant sauce and with a texture and taste reminiscent of the best lobster ever! The next day he returns to the restaurant, demanding to be be shown the “lobster” he had had last night. “I’ll get the chef” the waiter replies. Eventually the chef emerges from the kitchen and asks the food critic to follow him. The critic passes a tank with a pair of North Atlantic Lobsters silently observing him with their beady stalked eyes. However the chef continues on past them. “If they aren’t the lobster then what is?” The critic wonders to himself. He is taken through the kitchen and down a set of stairs. “Surely you don’t keep lobster in the wine cellar?!” the critic joked. “You’re right, we don’t” the chef replies, opening a hatch in the wine cellar that leads to second, hidden cellar. In this cellar is a giant pool, and in this pool is a group of the “lobster” he had eaten the night They are huge, as long as a man and possessed a flat tail, smooth semi-circular head, spines sticking out all over the place and large claws which they were using to tear into the fish that were being used to feed them. It truly was unlike any seafood he had ever seen. “What in the world is that?!” The critic exclaimed! “The Sea-Food Surprise” The chef replied. “Pentecopterus, a Sea-Scorpion”.

An illustration of a Pentecopterus swimming between vegetation.
Image Credit: Apokryltaros, https://commons.m.wikimedia.org/wiki/File:Pentecopterus_decorahensis.JPG

While a story like this could only be from the realm of science fiction, Pentecopterus decorahensis (Greek for “Decorah’s Penteconter Wing”) was a very real animal. It belonged to an order known as the Eurypterids, although they’re more commonly known as “Sea-Scorpions”. While it is another example of a cool paleontological nickname, “Sea Scorpion” is misleading. While most (but not all) members of this order did live in the sea they were not scorpions, but instead were part of a completely separate group. That being said modern scorpions and other arachnids such as spiders, along with horseshoe crabs, are the Sea Scorpions closest living relatives. This is unsurprising as Sea Scorpions looked like what would happen if a scorpion and a crab decided that they wanted to settle down and start a family! Sea Scorpions were a highly successful order of animals during the Palaeozoic era, having a timespan from 467 Million Years ago (during the Mid-Ordovician period) to 252 Million Years ago, succumbing to extinction during the “great dying” at the end of the Permian period. This means that Sea Scorpions were alive for longer than the dinosaurs!

What makes Pentecopterus special among this already interesting group is that it is the oldest species of Sea Scorpion discovered so far. Their fossils are estimated to be about 467 Million Years Old. These fossils were first formally described in 2015 by a team led by James C Lamsdell, who named the animal after the penteconter, an Ancient Greek galley ship that, like the animal, possessed a sleek shape. The original fossils were discovered in 2010 in the Winneshiek Lagerstätte near Decorah in Iowa, USA (Hence its full name). Winneshiek is an interesting place as it is located within the remnants of an old meteorite crater! When Pentecopterus was alive this 5 km wide meteorite crater was filled with sea water, creating a unique shallow marine environment. The relatively still waters and lack of oxygen on the crater floor resulted in the perfect conditions for fossilisation, and the relatively low salinity of the water meant that marine animals typical of the Ordovician oceans couldn’t live here, creating a unique ecosystem for its time. As a result of these conditions multiple Pentecopterus individuals (ranging from juveniles up to fully grown adults) were perfectly preserved, so perfectly in fact that the outline of the tiny sensory hairs can be seen.

As you can see in this comparison, a Pentecopterus was one large arthropod!
Image Credit: Slate Weasel, https://commons.m.wikimedia.org/wiki/File:Pentecopterus_Size.svg

So what exactly did Pentecopterus look like and how would it have behaved? Pentecopterus, like all arthropods (a group of invertebrates containing all insects and arachnids), would have had an exoskeleton divided into a series of distinct segments. At the front was a round, smooth and sleek head with two pairs of eyes; (one pair of compound-eyes at the front and a pair of smaller eyes at the top). Its body had 3 pairs of legs attached to it, that it used for walking on the sea floor (and maybe occasionally on land), and behind them a pair of broad paddles (that were uniquely shaped to this Sea Scorpion) used to help it swim and turn in the water. Finally at the back end there was a long, broad tail (known as a telson) that it used to power itself through the water. Pentecopterus also possessed a pair of vicious claws at the front of its body that it used to grab prey, (consisting of early jawless fish species and other arthropods). Pentecopterus belonged to a larger family of Sea Scorpions known as the Megalograptids. These are characterised by possessing many more spines on their legs compared to other Sea Scorpions, giving Pentecopterus a very spiny look. This would have been an unnervingly large animal to look at, growing as long as a human is tall (1.8 metres). However there were later Sea Scorpions that could grow even larger than this, with the largest being the 2.5 metre long Jaekelopterus!

Such a magnificent animal would have certainly been very eye catching and, if modern day crabs and lobsters are anything to go by, would potentially have made for a unique sea food delicacy, as the food critic in our story found out!

References/Extra Reading

Lamsdell et. al. 2015 paper describing Pentecopterus

Lamsdell, J.C., Briggs, D.E.G., Liu, H.P. et al. The oldest described eurypterid: a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa. BMC Evol Biol 15, 169 (2015). https://doi.org/10.1186/s12862-015-0443-9

Briggs et. al. 2018 paper reviewing the Winneshiek biota, home to Pentecopterus and other animals

Derek E.G. Briggs, Huaibao P. Liu, Robert M. McKay, Brian J. Witzke; The Winneshiek biota: exceptionally well-preserved fossils in a Middle Ordovician impact crater. Journal of the Geological Society ; 175 (6): 865–874. doi: https://doi.org/10.1144/jgs2018-101

A blog written by Palaeontologist Dave Marshall, and published in BMC Series blog, about the discovery of Pentecopterus and its significance

Marshall, Dave, “The oldest and the scariest sea scorpion: a giant discovery”, BMC Series blog, Sep. 1, 2015, blogs.biomedcentral.com/bmcseriesblog/2015/09/01/oldest-scariest-sea-scorpion-giant-discovery/

Another blog, written by Jim Shelton and published in YaleNews, on the discovery of Pentecopterus

Shelton, Jim, “Meet the newest ‘sea scorpion’: Pentecopterus, a predator from prehistoric seas”, YaleNews, Aug. 31, 2015, news.yale.edu/2015/08/31/meet-pentecopterus-new-predator-prehistoric-seas

Plateosaurus: A dinosaur that laid foundations

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Two Plateosaurus greeting each other, whether its friendly or not is debateable!
Image Credit: Nobu Tamara, http://spinops.blogspot.com/

The Triassic period was a time when the age of dinosaurs was just starting. The Permian/Triassic Extinction event of 250 million years ago (mya) had killed off almost 90% of all life, making it the biggest mass extinction event of all time. In the millions of years after this, the world was recovering. Life that survived this catastrophe expanded to fill in the many niches that had been left behind. This resulted in a weird menagerie of animals, dominated mostly by the reptiles. One group of reptiles known as the dinosaurs (you may have heard of them!) first evolved roughly 240 million years ago, and for the first 30 million years of their existence they competed with other reptile groups (e.g. rauisuchians, dicynodonts and cynodonts to name a few) for the inheritance of the earth. However by the Later Triassic, roughly 210 mya, dinosaurs were starting to gain the upper hand, and with the extinction of competing reptile groups were able to diversify into a variety of different shapes and sizes. This included their first evolutionary exploration into becoming giants. Whilst the true giants of the dinosaur world, the sauropods, had yet to appear on the scene their distant ancestors (and fellow members of the Sauropodomorpha sub-order) were already taking these first steps. These were the prosauropods. This group of dinosaurs were iconic members of the Late Triassic ecosystem and group members included some of the oldest dinosaurs yet discovered. The most famous member of this family would have been a common sight across the European edge of Pangea (a massive landmass consisting of all of the continents put together) 214-204 mya. Its name was Plateosaurus; meaning “flat lizard” (not because it was shaped like a pancake but because its fossils were noted to be much flatter than others discovered).

The first Plateosaurus fossils were discovered in 1834 by German Palaeontologist Johann Friedrich Engelhardt, and one Plateosaurus species (Plateosaurus engelhardti) was even named after him. This means that it was discovered just before Richard Owen coined the term “dinosaur”. However Plateosaurus wasn’t included as one of Richard Owen’s examples of dinosaurs because it was known only from fragmentary remains, which meant that it was poorly understood at the time. However this has changed, with multiple fossils of this animal having since been discovered (mostly in Germany but with some in Greenland and Norway too). One area which has produced multiple Plateosaurus fossils is a site near the village of Trossingen in the Black Forest, Germany. Here multiple Plateosaurus individuals have been unearthed, buried here over a period of time. One theory as to why this is the case is that the area contained thick sticky mud, in which the dinosaurs got stuck, before eventually collapsing and dying from exhaustion as they desperately tried to wiggle free (which is not a way to go!). However the large number of fossils means that Plateosaurus is now one of the best understood dinosaurs, with multiple papers being published about it, something I noticed when researching for this blog! These papers detail its anatomy and lifestyle, from studies of its skull, locomotion, its vertebrae and even its growth. As such Plateosaurus is one of the best known Triassic dinosaurs.

A reconstructed skeleton (known as “Skelett 2”) of Plateosaurus engelhardti in the Institute of Geosciences of the Eberhard-Karls University in Tübingen, Germany. This reconstruction is based on two individuals found at Trossingen.
Image Credit: FunkMonk, https://commons.m.wikimedia.org/wiki/File:Plateosaurus_Skelett_2.jpg

Due to the large concentration of fossils it is thought that Plateosaurus travelled in large herds. These herds would have stripped the landscape of almost any vegetation that they came across, the leaves of ferns and cycads being their favourite meal (though an estimated faster jaw closure speed than later sauropods, and different types of teeth, suggest that they might have eaten meat occasionally). To access this vegetation they would have used their long necks to reach leaves that were too high up for other herbivores. They also had claws to hook around and pull down plants and sharp crushing teeth to rip off leaves before swallowing them whole. Plateosaurus could also reach these heights because they walked around on two legs, with their long tail balancing out their long neck. This is a new discovery; previously it was thought they walked on all fours like their sauropod descendants. This theory is based on two main observations; firstly their front arms couldn’t pronate, meaning that they couldn’t lie their hands flat on the ground to support their weight; and secondly their centre of gravity was located over the hips, meaning that the hind limbs supported all of the weight. Further studies have also revealed another side to Plateosaurus. Deep depressions found in its dorsal vertebrae suggest that it possessed a bird like respiratory system with air sacs. This is surprising, as birds evolved from small, nimble theropod dinosaurs; not large long necked sauropods! One possible explanation is that bird like characteristics evolved much earlier in dinosaurs than previously thought, before they had diversified into their key groups. The other is that this system evolved convergently (i.e. it evolved separately in two different groups). These air sacs would have allowed Plateosaurus to carry around their large bulk more efficiently, and would have enabled them to process enough oxygen to have a more active, almost warm-blooded lifestyle. Plateosaurus is best envisaged as the Elephant of its day, approaching 10 metres long and 4 tons in weight. However not all adults would have reached this size. This is because Plateosaurus is one of only a few dinosaurs that is known to show “developmental plasticity”. In simple terms this is variation in growth between different Plateosaurus individuals, resulting in different adult sizes (in this case an adult range of 5-10 metres long and 0.6-4 tons). This is seen on a smaller scale in humans, with adults ranging from approximately 5”0 to as tall as 6”8. Being relatively large, a fully grown Plateosaurus would have been a tough proposition for most predators. Two exceptions however were the simply named Smok (meaning dragon in Polish), a 6 metre long archosaur reptile related to dinosaurs, and Liliensternus, a 5.2 metre long theropod dinosaur belonging to a family known as the Coelophysidae. Like the pro-sauropods this group were also dinosaurs that were characteristic of the Triassic, and fights between Liliensternus and Plateosaurus would be a subject for a segment in any nature documentary about life in the Triassic.

Plateosaurus has even appeared on the stage! This is from the Walking with Dinosaurs live show
Image Credit: Dark Dwarf, https://www.flickr.com/photos/darkdwarf/42887589745

Plateosaurus is undoubtedly one of the most famous dinosaurs of their earliest days. Its large size, plentiful fossils and connection to the later sauropods makes it a talisman among dinosaur enthusiasts. I think Walking with Dinosaurs summed up Plateosaurus the best, stating “This is the shape of things to come”.

EDIT: Based on studies of related pro-sauropods such as Massospondylus and Mussaurus (e.g. Otero et. al. 2019) it is thought that while Plateosaurus was a biped when fully grown, they were actually quadrupeds when they were juveniles. This theory is based on evidence such as observed changes in the centre of mass from the mid-thorax (in juveniles) to the pelvis (in adults), and in changes in body mass over time (e.g. Mussaurus grew from 60g when hatched, to 7kg at 1 years old, to over 1000kg when adults).

References/Extra Reading

Hofmann & Sander 2014 paper on the study of juvenile Plateosaurus fossils and developmental plasticity in Plateosaurus

Hofmann, Rebecca, and P Martin Sander. “The first juvenile specimens of Plateosaurus engelhardti from Frick, Switzerland: isolated neural arches and their implications for developmental plasticity in a basal sauropodomorph.” PeerJ vol. 2 e458. 3 Jul. 2014, doi:10.7717/peerj.458

Gunga et al 2007 paper estimating body mass and volume in Plateosaurus

Gunga, H., Suthau, T., Bellmann, A. et al. Body mass estimations for Plateosaurus engelhardti using laser scanning and 3D reconstruction methods. Naturwissenschaften 94, 623–630 (2007). https://doi.org/10.1007/s00114-007-0234-2

Mallison 2010 paper accessing range of motion of Plateosaurus legs and vertebrae, proving, among other results, that Plateosaurus walked on two legs only

Mallison, H. (2010). “The Digital Plateosaurus II: An Assessment of the Range of Motion of the Limbs and Vertebral Column and of Previous Reconstructions using a Digital Skeletal Mount.” Acta Palaeontologica Polonica 55(3): 433-458, 426.

Button, Barrett & Rayfield 2016 paper comparing the jaws of Plateosaurus with the Late Jurassic sauropod Camarasaurus

Button, D, Barrett, P, Rayfield, E. Comparative cranial myology and biomechanics of Plateosaurus and Camarasaurus and evolution of the sauropod feeding apparatus. Palaeontology, Vol 59, Iss 6, 887-913 (2016), https://doi.org/10.1111/pala.12266

Otero 2019 paper on the grow changes in Mussaurus, a close relative, that show a shift in locomotion from a quadruped to a biped

Otero, A., Cuff, A.R., Allen, V. et al. Ontogenetic changes in the body plan of the sauropodomorph dinosaur Mussaurus patagonicus reveal shifts of locomotor stance during growth. Sci Rep 9, 7614 (2019). https://doi.org/10.1038/s41598-019-44037-1

Bear + Dog = Amphicyon

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Reconstruction of Amphicyon ingens: The largest of the Bear-Dogs
Image Credit: roman uchytel, https://ru.wikipedia.org/wiki/%D0%A4%D0%B0%D0%B9%D0%BB:Amphicyon-ingens_reconstruction.jpg

16-18 million years ago, a fierce predator roamed the North American landscape. It had a long snout and a long tail like a modern day wolf, but it also had a stocky build, powerful forelimbs, plantigrade feet (i.e. it walked with its paws flat on the ground) and grew up to 2.5 metres long and 1.5 metres tall. These latter characteristics are much more like a modern bear. This was a weird mix of features. Anybody seeing this animal today, not knowing what it was, would think to themselves; “Is that a mutated bear?” “Or is it a new dog breed?”. This animal has the scientific name Amphicyon, meaning “Ambiguous dog”, however its common nickname is “Bear-Dog”. This is fitting because Amphicyon looks like an animal that would be the result of bizarre genetic cross-breeding of a Labrador and a Grizzly Bear! So the question that I will ask in this blog is, what in the world was it?

The genus Amphicyon (genus being a group of species, i.e. like the big cat group) was a very successful animal in its time, with multiple species stretching across the globe from North America to Europe to Africa. These species included Amphicyon longirams, which stalked what is now Florida, and Amphicyon Ingens; which reached a size comparable to the largest terrestrial carnivore alive today – the Polar Bear. In 2016 there was even a Chinese species discovered which was named Amphicyon zhanxiangi. Amphicyon first evolved in Europe and Asia, before migrating into North America during the mid-Miocene period 18 Million years ago. From this period they out-competed the resident mammalian carnivores such as the Hyaenodonts (large mammalian predators with shearing teeth), the Entelodonts (who have the awesome nickname of “Terminator Pigs”) and other Bear-Dogs to become the top dog (pun intended) of the Miocene landscape.

A map showing the geographical range of Amphicyon. As you can see Europe, Asia, North America and Africa all had their own Amphicyon species!
Image Credit: Noles1984, https://en.m.wikipedia.org/wiki/File:Amphicyon_range.png

Bear-Dogs as a whole are thought to have had a variety of hunting strategies that varied between species. Amphicyon, being larger and more stocky in build, would have hunted somewhat like a bear; surprising their prey and pursuing it for a short distance before using their muscular forelimbs and large body size to pin it down before biting at the neck and body to finish it off. Being an ambush hunter it wouldn’t have regularly partaken in long chases, though it was able to pursue prey for longer than other ambush predators. Their size would have allowed them to hunt larger mammalian herbivores, which would have included early rhinos. We know this from a fossil unearthed from Portugal of the lower jaw of the extinct rhino Iberotherium. This jaw has clear puncture marks in it made by the teeth of a large carnivore. A study, conducted by Antunes, Balbino and Ginsberg in 2006, concluded that the culprit was Amphicyon giganteus as it was the only known carnivore from the same time and place large enough to inflict these type of wounds (though whether it did so when hunting or scavenging this Iberotherium is unknown). Meanwhile other species of Bear-Dogs, such as Borocyon, had longer legs and more slender bodies. This suggests that they hunted more like modern day wolves; pursuing their prey over long distances. While Amphicyons diet would have mostly consisted of meat it is thought that other Bear-Dogs might also have been omnivorous to a degree, eating plant matter and berries to supplement their diet. It is also thought that they, along with other Bear-Dogs, exhibited denning behaviour, digging out burrows in which they could raise their young and take shelter. Like all mammals they would have exhibited high levels of parental care, raising pups until they were old enough to fend for themselves. Amphicyon also exhibited sexual dimorphism, just like bears, with the males being substantially larger than the females.

A mural depicting a scene from the 16-13 million year old Mascall assemblage in Oregon, USA, showing an Amphicyon hunting a Miolabis.
Image Credit: National Park Service, https://www.nps.gov/joda/learn/nature/mascall.htm

So to answer the question posed at the beginning of this blog, what exactly was Amphicyon? A bear or a dog? Well the answer is in fact neither. Amphicyon belonged to a family known as the Amphicyonidae, which included it and all other species of Bear-Dogs. This family belonged to an order known as the Caniformia, which also contains the dog and bear families as well as foxes and sea lions. As a result Amphicyon and its kin were actually close cousins of bears and dogs, separating from them in the evolutionary tree around 40 million years ago during the Eocene period. The Bear-Dogs evolved into a wide range of shapes and sizes, filling a variety of niches. However, despite its success, Amphicyon and its kin would sadly go extinct around 7.2 million years ago. The main cause of this was the changing environment at the end of the Miocene. The climate became dryer, which resulted in the emergence of more open plains. This meant that the slower, bulkier Amphicyon could not find the cover it needed to ambush its prey. This meant that they struggled to find enough food to support their large size. Also (rather ironically) another factor was the emergence and success of the dogs and bears. Dogs were more specialised in the endurance hunting style that is effective on open plains, and some had jaws that could crush bone, something Amphicyon couldn’t do despite its impressive appearance! (In fact one group of dogs, named the Borophaginae, are commonly referred to as the “bone-crushing dogs”!) Bears meanwhile had a more omnivorous diet than Amphicyon, giving them access to a wider range of food. Dogs and Bears were also generally smaller, so didn’t require as much food to keep them alive. In addition at about this time the first Sabre-Tooth Cats were evolving, bringing yet more competition. These three groups together took over all the niches that had previously been occupied by Amphicyon and its relatives. As a result this magnificent group of animals were squeezed out and confined to the pages of pre-history.

It’s a shame too, as a pet Amphicyon would have been not only a cute puppy but also grown to be an effective “guard dog”. It would certainly draw more than a few glances when you took it for a walk!

References/Further Reading

Antunes, Balbino & Ginsberg 2006 paper on Iberotherium jaw fossil showing bite marks made by Amphicyon

Antunes, Miguel. Telles, Balbino, Ausenda C., Ginsberg, Léonard. Ichnological evidence of a Miocene rhinoceros bitten by a bear-dog (Amphicyon giganteus), Annales de Paléontologie, Volume 92, Issue 1, 2006, Pages 31-39,

Florida Museum information page on Amphicyon longirams

Morse, Paul E. “Amphicyon longiramus” Florida Museum, Oct. 5, 2012, floridamuseum.ufl.edu/florida-vertebrate-fossils/species/amphicyon-longiramus/

Sorkin 2006 paper on Amphicyon and Ischyrocyon diet and hunting behaviour

Sorkin, Boris. (2006). Ecomorphology of the giant bear-dogs Amphicyon and Ischyrocyon. Historical Biology. 18. 10.1080/08912960600618073.

Jiangzuo et. al. 2016 paper describing the Amphicyon zhanxiangi

Qigao Jiangzuo, Chunxiao Li, Shiqi Wang & Danhui Sun (2018) Amphicyon zhanxiangi, sp. nov., a new amphicyonid (Mammalia, Carnivora) from northern China, Journal of Vertebrate Paleontology, 38:6, DOI: 10.1080/02724634.2018.1539857