Yi qi: The Dragon of the Jurassic

The Jurassic Dragon takes flight!
Image Credit: Emily Willoughby, https://commons.m.wikimedia.org/wiki/File:Yi_qi_restoration.jpg

In a dense forest, full of hissing, rumbling and bellowing noises, a dragon perches on a branch. Using its sharp eyesight it locates its next meal; a large beetle crawling along a tree trunk 50 metres away. The dragon stretches its leathery wings and takes flight, swooping down silently with barely a flap towards its prey. However, just before the dragon can strike the beetle notices and unfurls its own wings in a desperate attempt to escape. But with a couple of quick flaps the dragon adjusts in mid-air and intercepts, snapping it out of the air with its toothy jaws. The beast lands and swallows the meal. But this is only a starter, and the little dragon surveys the forest again before moving on in search of the main course.

Believe it or not this really did occur in the Late Jurassic forests of China. But with one difference. The animal in question was not a mythological dragon, but a dinosaur named Yi qi.

The binomial name Yi qi, meaning “Strange Wing” in Chinese, is the shortest scientific name given to any dinosaur, and one of the shortest names of any animal living or extinct. It belonged to a family of theropod dinosaurs known as the Scansoriopterygidae (a real tongue twister of a name). Yi qi is one of only three known members of this group (the others being Epidexipteryx and Epidendrosaurus/Scansoriopteryx) and as a result relatively little is known about their evolutionary history and general lifestyle. The Scansoriopterygidae were part of a wider theropod order known as the paravians; which includes the dromaeosaurs (i.e. raptors) and all birds (that’s right ALL birds). However the Scansoriopterygidae seem (unless future discoveries say otherwise) to be an example of an evolutionary dead end as they are only known from sites from the Mid-Late Jurassic (and potentially Early Cretaceous) China and nowhere else.

Size comparison between Yi qi and a human being
Image Credit: Matthew Martyniuk, https://commons.m.wikimedia.org/wiki/File:Yi_scale.png

Yi qi was roughly the size of a pigeon with toothed jaws, forward facing eyes, sharp claws, long thick tail feathers and simple filament feathers covering its body, head and upper arms. The fossilised feathers are so well preserved that even the melanosomes (the small organelles that give feathers and other biological structures colour) were clearly preserved. Examination of the shape of these melanosomes, and comparison with melanosomes in living birds, showed that Yi qi had a black/grey body with reds and yellow colours on its arms. This gave it a distinctive contrasting colour scheme with the red/yellow arms perhaps used for signalling or species recognition. So far from this description Yi qi sounds more like a bird than a dragon! However when palaeontologists examined its forearms they made an astonishing discovery. An elongated third finger extended from both its hands and a long rod like bone (known as a styliform) jutted out from its wrist. These supported a skin membrane, known as a patagia, connecting the ends of its elongated fingers to the end of the styliform. It’s theorized that this membrane would also have stretched from the end of the styliform to the body, giving Yi qi “bat-like” wings (though another competing theory is that Yi qi would have had skin membranes like those of a modern gliding tree frog). These unique wings give Yi qi and its close relatives an appearance unlike any dinosaur, bird or pterosaur, one that draws comparisons with a dragon (specifically a “wyvern”). Whether Yi qi would have used these wings for powered flight or gliding (like a flying squirrel) is unclear. However it may have employed a combination of the two; long distance gliding (or as Buzz Lightyear would say “falling with style!”) and powered flapping for initial take off and manoeuvring through the air. Yi qi’s discovery also shows that flight had evolved in dinosaurs on multiple occasions, with the bat winged Yi qi being only one such evolutionary experiment.

The one and only Yi qi fossil. Note the feather covering around its body and head, as well as the styliform on its elongated wrist.
Image Credit: Kumiko, https://www.flickr.com/photos/kmkmks/27011985534/

All we know about Yi qi so far comes from one remarkable fossil that was discovered in 2007 in the Hebei province of China. It was found in the Mid-Late Jurassic age Tiaojishan formation of rocks. This is important as a large proportion of feathered dinosaurs are known from the Early Cretaceous onwards (20-30 million years after Yi qi). Therefore its discovery shows that feathers were present on dinosaurs far earlier than initially thought, with some palaeontologists suggesting that they originated even earlier than Yi qi. After its discovery the fossil was studied by a team led by the eminent Palaeontologist Xu Xang, who has described and named a whole menagerie of Chinese dinosaurs (e.g. the feathered tyrannosaur Yutyrannus). Yi qi was revealed to the world in a paper released in 2015 and it’s strange, dragon like appearance meant that it, like many dinosaur discoveries from China in the last few decades, made headlines around the world.

Yi qi is one of the most unusual dinosaur discoveries of the last decade. It proves, beyond a shadow of a doubt, that the world of palaeontology continues to unearth astounding discoveries. Discoveries that add more paint to the canvas that is the history of life on earth.

References/Further Reading

The original Xu et. al. 2015 paper describing Yi qi

Xu, X., Zheng, X., Sullivan, C. et al. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings. Nature 521, 70–73 (2015). https://doi.org/10.1038/nature14423

A blog (originally from tetrapod zoology) published in Scientific American by palaeontologist Darren Naish on Yi qi and theories on its lifestyle and features

Naish, Darren “Yi qi Is Neat but Might Not Have Been the Black Screaming Dino-Dragon of Death”. Scientific American, May. 5, 2015, blogs.scientificamerican.com/tetrapod-zoology/yi-qi-is-neat-but-might-not-have-been-the-black-screaming-dino-dragon-of-death/

A blog written by Nick Garland and published in Earth Archives on Yi qi

Garland, Nick “Meet Yi qi, the dinosaur with bat-like wings and feathers”. Earth Archives, 2015, eartharchives.org/articles/meet-yi-qi-the-dinosaur-with-bat-like-wings-and-feathers/

Stegosaurus: A Jurassic Icon

Sophie the Stegosaurus. On display at the Natural History Museum in London, England
Image Credit: Aya Reyad, https://commons.m.wikimedia.org/wiki/File:%D9%85%D8%AA%D8%AD%D9%81_%D8%A7%D9%84%D8%AA%D8%A7%D8%B1%D9%8A%D8%AE_%D8%A7%D9%84%D8%B7%D8%A8%D9%8A%D8%B9%D9%8A_8.jpg

In late 2014 the Natural History Museum revealed a new dinosaur display. It is situated almost immediately after you go through the east entrance, and is different from most fossils in that she has her own identity. Her name is Sophie, and she stands in front of the giant globe that marks the entrance to the Earth Hall as if guarding it. While she is small for her genus she is nevertheless an imposing sight; larger than any living elephant, two rows of plates lining her back and a spiked tail that she raises in defence. Her original home was the coniferous forests and floodplains that would later become the Western United States, and she walked the land 150 million years before humans. She is a special dinosaur, one that is instantly recognisable the world over by dinosaur lovers and casual observers alike. She is power, she is serenity, she is a Stegosaurus.

The first fossils of Stegosaurus (“roofed lizard”) were discovered in the state of Colorado, USA by Marshall Parker Felch in 1876. Felch was a veteran of the American Civil War and was a fossil hunter working with the palaeontologist Othneil Charles Marsh, who subsequently described and named this as a new dinosaur in 1877. The fossils were unearthed from what is known as the Morrison Formation; a 1 million square kilometre Late Jurassic rock sequence that stretches across a large area of the western USA including Arizona, Utah and Wyoming. The very first reconstructions of Stegosaurus was based on the initial assumption that it was an extinct turtle! This resulted in a wildly different animal to what we think today. In this initial reconstruction it reared on two legs, its spines were positioned on its back, its plates were laid flat on its back like roof tiles (hence “roofed lizard”) and it had two brains. That’s right those Victorian palaeontologists though Stegosaurus had TWO brains! A small, walnut sized brain in its head, and a “second brain” located in its hips. The thinking was that its main brain was so small compared to its body size that it needed a second one to help control its hind legs and tail. We know of course that it didn’t really have two brains. The “second brain” is thought to be a body cavity containing glycogen stores to help provide energy, in the form of glucose, to its muscles.

Since those early days many Stegosaurus fossils have been unearthed with Stegosaurus stenops, the species that Sophie belongs to, being the most common (in fact Sophie is the most complete Stegosaurus skeleton ever found). This has allowed palaeontologists to construct a more detailed picture of what this animal was like. It was a relatively slow moving, four legged animal belonging to its own group of ornithischian dinosaurs known as the Stegosaurs. Stegosaurus is the largest and most iconic member of the group, but Stegosaurs have been discovered across the world; such as Kentrosaurus from Africa, Tuojiangosaurus from Asia and Dacentrurus from Europe. Stegosaurus and its relatives were herbivores, using peg-like teeth to strip leaves off low growing ferns, mosses and shrubs. To help digest this, Stegosaurus would intentionally swallowed small stones (called gastroliths) that sat in its stomach and helped to grind up incoming plant matter. This diet may not seem very exciting, but consuming vast quantities of these simple shrubs allowed Stegosaurus to grow to a huge size; up to a maximum of 9 metres long and weighing 7 tons in the largest species (Stegosaurus armatus).

Size comparison between a human and two Stegosaurus species: S.ungulatus and S.stenops (the species Sophie belongs to)
Image Credit: KoprX, https://commons.m.wikimedia.org/wiki/File:Stegosaurus_size_comparison.svg

Stegosaurus is characterised by two eye-catching features. The first is the two rows of alternating pentagon shaped plates that stretch along its back from its neck to near the end of its tail. These plates were covered in a sheath of a horn like material called keratin, the same material that makes up fingernails, horns and antlers. Currently the best explanation for what these huge, lavish structures were used for is that they were multi-functional. The main use is in display and signalling to others. Whether males trying to attract a mate, Stegosaurus’ sizing each other up, ward off predators or to simply recognise each other these plates position on the body and their size would have made them very effective “billboards”. As a bit of fun speculation I wonder if these plates could have been brightly coloured, especially since it’s thought that the plates might have had an outer covering of thin skin. Unique variations in plate colours between different individuals would have acted like a fingerprint, allowing for identification and signalling. Another idea is that Stegosaurus used its plates to help regulate its body temperature. To do this Stegosaurus would have pumped blood into the plates, allowing the heat to be radiated outwards or to be taken in. This was a popular theory for a long time and while the size and positioning of the plates would have allowed them to passively radiate heat, and there are some channels within the plates that could have aided with this, the latest thinking is that the plates weren’t especially adapted for heat radiation or absorption.

The other defining feature of Stegosaurus was the two pairs of long spines that jutted out sideways from the end of its tail. This formed a structure that is referred to as a “Thagomizer”. This term is unique as it originated from a cartoon in the comic “The Far Side”, which had a caveman name the spiny tail after the fictional “late Thag Simmons”. The name has stuck since with palaeontologists accepting it as a valid scientific term. The thagomizer was a deadly weapon that Stegosaurus used by positioning itself sideways or with its tail facing its attacker, giving it room to swing and forming an impenetrable barrier to protect the more vulnerable front end. A thagomizer would have certainly been required as Stegosaurus was prey for the large predators stalking the area at the time. Large theropod dinosaurs such as Torvosaurus and Saurophagonax would have been among these, but by far the most notorious was Allosaurus. Fossil evidence of conflicts between Stegosaurus and Allosaurus have been found frequently, ranging from a damaged piece of Stegosaurus plate to large holes in Allosaurus bones caused by a Stegosaurus thagomizer (including one fossil where a thagomizer went straight through an Allosaurus pelvis, hitting a place where the sun doesn’t shine!). It seems that the two dinosaurs clashed frequently, sharing a rivalry similar to the one between T-Rex and Triceratops 90 million years later. Thagomizers may not have been Stegosaurus’ only method of defence. One theory is that Stegosaurus might have lived in small groups, with the numbers giving mutual protection. Furthermore it’s been speculated that Stegosaurus might also have formed mixed herds (like those seen between Wildebeest, Zebra and Ostrich’s on the African Savannah) with other plant eating dinosaurs such as the smaller Camptosaurus. This arrangement would have provided mutual benefits; Camptosaurus’ keen eye sight would have allowed it to act as a scout, while the Stegosaurus would have been the heavily armoured knights.

A life like model of Stegosaurus
Image Credit: DinoTeam, https://commons.m.wikimedia.org/wiki/File:Stegosaurus_02_DinoPark_Ko%C5%A1ice.jpg

For me personally Stegosaurus has held a fond place in my heart for a long time. It was my favourite dinosaur when I was young, so much so that I still have a toy one amongst my collection. I think I was fond of it it so much because not only did it have an eye catching appearance, quite unlike any animal alive today, but also because I saw it almost like a superhero. Normally it would peacefully munch on ferns and go about its business. But if it or its herd were threatened it wouldn’t hesitate to swing into action, lashing its spiked tail at any predator brave enough to take it on. While many prehistoric animals have left a mark on me over the years, none have done so quite like Stegosaurus, and for that I will always love it.

References/Further Reading

A paper (Carpenter et.al. 2005) on the predator-prey relationship between Allosaurus and Stegosaurus

Carpenter, Kenneth & Sanders, Frank & Mewhinney, Lorrie & Wood, Lowell. (2005). Evidence for Predator- Prey Relationships Examples for Allosaurus and Stegosaurus, The Carnivorous Dinosaurs, Chapter: 17, 325-350

A paper (Farlow, Hayashi & Tattersall 2010) reviewing the possible heat regulatory properties of Stegosaurus plates, using comparisons with Alligator osteoderms

Farlow, J.O., Hayashi, S. & Tattersall, G.J. Internal vascularity of the dermal plates of Stegosaurus (Ornithischia, Thyreophora). Swiss J Geosci 103, 173–185 (2010). https://doi.org/10.1007/s00015-010-0021-5

A blog article, published on Scientific American (originally on Tetrapod Zoology), by renowned palaeontologist Darren Naish on Stegosaurus plates and their research history

Naish, Darren, “The Stegosaurus Plate Controversy”, Scientific American, Jul. 11, 2016, blogs.scientificamerican.com/tetrapod-zoology/the-stegosaurus-plate-controversy/

An article by The Evolution Institute on the geology and fossils of the Morrison Formation

Marano, Michael, “Utah’s Morrison Formation: A Fossil Treasure Chest”, The Evolution Institute, Dec. 13, 2012, evolution-institute.org/utahs-morrison-formation-a-fossil-treasure-chest/

A New Scientist article on the origin of the word “thagomizer”

“The word: Thagomizer”, New Scientist, Jul. 5, 2006, newscientist.com/article/mg19125592-200-the-word-thagomizer/?ignored=irrelevant

A National Geographic article on the history of Stegosaurus reconstructions

Laelaps, “Out With the Old Stegosaurus”. National Geographic, Apr 29, 2013, nationalgeographic.com/science/phenomena/2013/04/29/out-with-the-old-stegosaurus/

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/

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

Leaellynasaura: A dinosaur that called the South Pole home

A drawing of the South Poles resident dinosaur Leaellynasaura
Image Credit: El fosilmaníaco, https://commons.m.wikimedia.org/wiki/User:El_fosilman%C3%ADaco

It’s hard to imagine any land based animal living at the South Pole. The frozen wastes, completely prevents any significant plant growth, complete darkness covers the area for about half the year, and temperatures are nearly always well below freezing. This results in an environment where the largest life-form is no more than microscopic. However for a sizeable chunk of earth’s history there was no permanent ice cap at the South Pole. Instead temperate forests covered the continents that were located there. During the Early to Mid-Cretaceous period, (around 105-110 million years ago), a landmass that would eventually break up to become Antarctica and Australia was present at the south pole of our planet. If you trekked through this land, often with only the southern lights illuminating the landscape, you might be able hear the chirps of a small, unassuming little dinosaur piercing the otherwise silent frozen forest. These sounds belonged to an ornithopod known as Leaellynasaura amicagraphca (Latin for “Leaellyn’s lizard”, with “amicagraphica” referring to the friends of Museum Victoria who helped with the research).

When a prehistoric animal is given its scientific name, the usual procedure is to either; 1. Name it because of a distinguishing feature; 2. Name it after the area it was discovered in; or 3. Give it an eye catching name that involves the words “terror” or “massive” or “weird”. However Leaellynasaura bucks this trend by instead being named after Leaellyn Rich, the young daughter of Palaeontologists Thomas and Patricia Rich, who first discovered Leaellynasaura in 1989 (a great present for any person!). The fossils were found at a place known as Dinosaur Cove, which is located just outside of Melbourne, Australia. This site, and others in Australia, have shown that Leaellynasaura lived alongside a wide range of other animals. This included other dinosaurs, such as the large vegetarian iguanodontid Muttaburrasaurus and the mid-sized hunting theropod Australovenator, as well as a giant 5 metre long amphibian named Koolasuchus. Fans of the hit BBC documentary “Walking with Dinosaurs” might recognise some of the names I’ve just mentioned. This is because the fifth episode, titled “Spirits of the Ice Forest”, is actually based on this fossil assemblage.

A selection of Leaellynasaura amicographica fossils.
Image Credit: Kumiko, https://www.flickr.com/photos/kmkmks/8086848566/

Leaellynasaura itself was a small dinosaur, with estimates varying between 1-3 metres. It is unclear what specific group of Ornithopod Dinosaurs it belonged to, however it is similar in anatomy to the Hypsilophodontids (try saying that five times fast!). These dinosaurs are characteristically small, bipedal, nimble herbivores, using their beaks to browse vegetation, all whilst scampering between larger herbivores (the best modern analogue might be modern day Gazelles). When you look at the skeleton of Leaellynasaura a few features stand out. Firstly it had large eye sockets relative to its skull. Combined with a large optic lobes in its brain cavity this suggests that Leaellynasaura had excellent eyesight, allowing it to spot predators and locate juicy plants to eat. Secondly its tail was very long, nearly 3/4 of its entire length! This tail contained over 70 vertebrae and lacked many of the ossified tendons involved in stiffening and strengthening the tail of other dinosaurs. This means that Leaellynasaura probably possessed a remarkably flexible tail, capable of a wide variety of movement (maybe even curling round up and around its body). The function of this long tail is unclear at the moment, though it has been theorised that it was involved in display, especially when combined with any feather covering that it likely possessed.

Size comparison between Leaellynasaura amicagraphica and an adult human. Note Leaellynasaura’s proportionally long tail that takes up 2/3rds of its total length!
Image Credit: Slate Weasel, https://en.m.wikipedia.org/wiki/File:Leaellynasaura_Size.svg

The biggest challenge that Leaellynasaura would have faced would have certainly been surviving the elements. As Dinosaur Cove was located well within the Antarctic Circle it would have endured the same seasonal variations that Antarctica does today; 6 months of near permanent sunshine followed by 6 months of near permanent darkness. So how could a dinosaur possibly have coped with these long periods of darkness, where temperatures would’ve regularly dropped well below freezing? This is where its key distinguishing features come into play. Its large eyes would have allowed it to see well in the dim light, key for spotting what little edible plant matter could be found in the frozen ground. Its long flexible tail could potentially have been wrapped round itself when the animal rested in order to keep itself warm (rather like your pet cat does when it is taking a nap!). Another strategy to protect itself against the cold could have been taking shelter in burrows. Fossil burrows have been found at Dinosaur Cove and it has been suggested they could have been made by Leaellynasaura. Support for this theory comes from fossils in Montana of a close cousin, named Oryctodromeus. Fossilised remains have been found preserved in the burrows that they lived in. Also because of fossil evidence from ancestral relatives (such as Tianyulong) it has been suggested that Leaellynasaura was covered in feathers. Speculations range from simple velvety fuzz to a multi-layered fluffy coat according to different reconstructions. The feathered coat makes sense considering the cold climate, certainly allowing it a much greater degree of insulation than traditional reptilian scales.

It may not be the biggest, or possess giant claws, bone clubs or spines, but Leaellynasaura in its own way was just as remarkable a dinosaur as any that have ever existed, perfectly adapted to an environment that was previously thought to be impossible for a reptile to live in. Also, especially if we assume it did possess a thick fluffy coating of feathers with its big eyes and long tail, Leaellynasaura would have certainly been a contender for the cutest dinosaur to ever exist! If it were alive today dog grooming shows would have serious competition from Leaellynasaura grooming shows!

References/Further Reading

Article on Australian Dinosaurs (including Leaellynasaura) and Dinosaur Cove

Udurawane, Vasika, “Dinosaurs down under”, Earth Archives, 2016, eartharchives.org/articles/dinosaurs-down-under/

A 2017 study by Sharp et al. which put a Leaellynasaura fossil through a CT scanner

Sharp, Alana & Regalado Fernandez, Omar & Siu, Karen & Rich, Tom. (2017). Revealing the skeleton of the polar dinosaur Leaellynasaura amicagraphica using synchrotron computed tomography, Society of Vertebrate Paleontology (SVP) 77th Annual Meeting.

The Western Australian Museum’s article about Leaellynasaura, talking about its anatomy, size and growth.

“Leaellynasaura”, Western Australian Museum, 2014, museum.wa.gov.au/explore/dinosaur-discovery/leaellynasaura

Dakotaraptor: The Thief from Hell Creek

Dakotaraptor in all its feathered glory!
Image Credit: Emily Willoughby, https://commons.m.wikimedia.org/wiki/File:Dakotaraptor_wiki.jpg

If there was only one place and time that I could take someone new to the topic of dinosaurs, it would undoubtedly be Hell Creek, 65 million years ago. Here, in an environment of lush forests and temperatures similar to Spain today, lived a variety of instantly recognisable dinosaur icons. You could see a Triceratops lumbering through the woods, view a herd of Edmontosaurus browsing the nearby vegetation, hear two Pachycephalosaurus crashing their heads together and ensure to keep us a safe distance from the solid club tail of an Ankylosaurus. To cap it all off you would see the most famous dinosaur of them all, Tyrannosaurus Rex. In one area I could show someone a ceratopsian, a hadrosaur, a pachychephalosaur, an ankylosaur and a tyrannosaur all in one afternoon. Now, thanks to new fossils described only four years ago, you can add a large dromaeosaur (aka, “raptor”) to that list.

This animal has been given the name Dakotaraptor steini (“Stein’s Dakota Thief”), after the State of Dakota where Hell Creek is located and in honour of palaeontologist Walter Stein. It was discovered by a team led by Robert DaPalma, who described some partially articulated fossilised skeletons of a few individuals including arm and leg bones, some tail vertebrae and teeth. There was also a “wishbone” that was thought to belong to Dakotaraptor, however a study by Arbour et al in 2016 showed that this was actually a turtle bone (an honest mistake on the DePalma and his teams part!) These fossils showed that this dinosaur was no chicken! Measuring 5 and a half metres long and 1.8 metres tall it would have been almost exactly the same size as the famous Velociraptors from the film Jurassic Park. However for a large raptor Dakotaraptor was relatively lightweight, partly due to its vertebrae having air spaces within them. Combing this with legs built for long strides and Dakotaraptor would have been able to achieve top speeds of around 30-40 mph, that’s as fast as a greyhound! Just like the Jurassic Park raptors, Dakotaraptor would have been a lethal predator, hunting in packs to take down large herbivorous dinosaurs. To do this Dakotaraptor needed some serious weaponry, luckily that’s just what it had in the form of the raptors signature weapon; the killing claw on its feet. Dakotaraptor’s was especially big, measuring 9 and a half inches, with a serrated hook shaped end. It used to be thought that raptors used their claw in order to violently slash and disembowel prey. However it is now thought that the claws were mainly used to hold onto large struggling prey and to pin down smaller animals, rather like a modern bird of prey.

A illustration of Dakotaraptor showing the position of all the known bones (highlighted in white).
Image Credit: PaleoNeolitic, https://commons.m.wikimedia.org/wiki/File:Dakotaraptor_Skeleton_Reconstruction.jpg

The resemblance to birds doesn’t end there. Dakotaraptor, just like all other raptors, was completely covered in feathers (sorry if I’ve just ruined your childhood memories of scaly raptors!). In fact Dakotaraptor is the first large raptor to have direct evidence of feathers (previously it had been inferred that they had them based on smaller relatives possessing them). On its ulna (one of the arm bones) palaeontologists discovered a series of 15 regular notches running along the bone. These notches are called quill knobs and their purpose is to act as anchor points for long pennaceous feathers to attach to. As a result Dakotaraptor would have sported a small pair of wings! However these wings weren’t strong enough for flight (Dakotaraptor was already lethal enough without needing to fly!) Instead, through flapping and balancing motions it could have helped keep the raptor steady while running or holding on to prey. Wing feathers could also have been for display, with potentially bright colours being used to attract a mate or to show off to rivals (a trait common in modern birds). Feathers could have made the animal look bigger and more intimidating and could even be used to cover its young while nesting. With a full head and body of soft feathers, a feathery tail fan and small wings, you might have mistaken Dakotaraptor (and other raptors for that matter) for a giant grounded eagle or hawk from a distance.

Being discovered at Hell Creek also means that Dakotaraptor, just like Tyrannosaurus and Triceratops, was one of the last of the dinosaurs. It would have lived right up until the end of the Cretaceous period and would have been another victim of the asteroid strike on the Gulf of Mexico 65 million years ago. After the impact and resultant climate change the vegetation that its plant eating prey relied on disappeared. With its prey gone Dakotaraptor would disappear too, and with it the entire line of fast, remarkably bird like dinosaurs known as the dromaeosaurs would be no more.

Size comparison between Dakotaraptor and an adult human. With how close the human is he won’t be waving for long!
Image Credit: Matthew Martyniuk, https://commons.m.wikimedia.org/wiki/File:Dakota_raptor_scale_mmartyniuk.png

Now I’m going to end this blog with the question that I’m sure some people would be asking. Would Tyrannosaurus Rex and Dakotaraptor have clashed? Such confrontations would have certainly been possible as the two dinosaurs lived in the same place at the same time, and might have hunted similar prey at times. However fights may not actually have been that common. Dakotaraptor would have mostly targeted smaller and faster prey than T-Rex. As a result of this it would have occupied a different role (or “niche”) in the Hell Creek environment, that of a medium sized predator. This idea is called “niche partitioning” and we see it happen today on the African savannah, where cheetahs hunt fast gazelles while lions hunt the larger wildebeest, and so don’t compete with each other (except over a carcass). As a result Dakotaraptor might not have directly competed with Tyrannosaurus Rex for food. But for the sake of fun, what if they had come into conflict? Well a single Dakotaraptor would probably have fared against an adult T-Rex about as well as the Velociraptor at the end of Jurassic Park did! However a pack of Dakotaraptors against an adult, or an adolescent T-Rex would have been a different proposition. One could even envision a Dakotaraptor pack chasing a Tyrannosaurus off a kill in exactly the same way as a pack of Hyenas do to Lions on the African Savannah. So that fight between a T-Rex and a raptor at the end of Jurassic Park could have happened, just with a lot more feathers flying around!

UPDATE: A new study (Frederickson, Engel & Cifelli 2020), published in the journal Palaeonon the 3rd of May 2020, has cast doubt on the theory that raptors like Dakotaraptor lived and hunted in packs. The study examined the level of tooth carbon isotopes in juvenile and adult Deinonychus, a smaller and earlier relative of Dakotaraptor. What they found was the carbon isotope levels were rich in juveniles but depleted in adults. This indicates that they were eating different prey and this difference is consistent with animals like crocodiles who don’t live in packs. In pack hunting animals, such as Lions, both young and adult individuals eat the same food as they’re often sharing a kill between members of the group, so have the same or similar tooth carbon isotope level. In short, raptors like Dakotaraptor May have lived a more solitary life.

References/Further Reading

A National Geographic article, written by Ed Yong, on the use of the raptors killing claw

Yong, Ed, “Deinonychus and Velociraptor used their killing claws to pin prey, like eagles and hawks”, National Geographic, Dec 14, 2011, nationalgeographic.com/science/phenomena/2011/12/14/deinonychus-and-velociraptor-used-their-killing-claws-to-pin-prey-like-eagles-and-hawks/

The DePalma et. al. 2015 paper describing the first Dakotaraptor fossils

DePalma, Robert A., Burnham, David A., Martin, Larry D., et. al., The first giant raptor (Theropoda: Dromaeosauridae) from the Hell Creek Formation, Paleontological Institute, Paleontological Contributions;14, (2015), https://doi.org/10.17161/paleo.1808.18764

The Arbour et. al. 2016 paper that pointed out that one of the fossils was actually a turtle

Arbour VM, Zanno LE, Larson DW, Evans DC, Sues H. 2016. The furculae of the dromaeosaurid dinosaur Dakotaraptor steini are trionychid turtle entoplastra. PeerJ 4:e1691 https://doi.org/10.7717/peerj.1691

Another blog, by Brian Switek, talking about possible interactions between Dakotaraptor and T-Rex

Switek, Brian, “Did Dakotaraptor Really Face Off Against Tyrannosaurus?”, goodreads, Nov. 25, 2015, goodreads.com/author/show/3958757.Brian_Switek/blog?page=23

Frederickson, Engel & Cifelli 2020 study that used tooth carbon isotope data to indicate that raptors may not have been pack hunters (EDIT)

J.A. Frederickson et al, Ontogenetic dietary shifts in Deinonychus antirrhopus (Theropoda; Dromaeosauridae): Insights into the ecology and social behavior of raptorial dinosaurs through stable isotope analysis, Palaeogeography, Palaeoclimatology, Palaeoecology (2020). DOI: 10.1016/j.palaeo.2020.109780

Hatzegopteryx: The King of Hațeg Island

The Kings of the Island
Image Credit: Mark Witton, https://commons.m.wikimedia.org/wiki/File:Hatzegopteryx.png

A wildlife safari to the island of Hațeg was going to be perfect they said. Warm sunny beaches, unspoiled wilderness and herbivorous dinosaurs small enough to ride like ponies. What could possibly go wrong!

But now the tourists are running for their lives through the fields of ferns, not daring to stop as the top predators of the island follow closely behind. They had been warned that they were dangerous, but their guide had said that they would be fine, they wouldn’t get too close and he would use his gun if they did. Sadly the guide had been eaten about fifteen minutes ago. The tourists keep going, trying to get as far away from the rasping squawks as they can. One of them is picked up of the ground, disappearing out of sight. Another suffers the same fate. Suddenly the last one trips and rolls forward. Coughing and spluttering he turns around, and sees one of the beasts towering over him. It regards him with its beady eyes before leaning its large head down and grabbing his leg with its beak. The beast leans its head back and with one final gulp the tourist joins his friends. The island once again belongs to its king.

The movie executives look up from the script they’d just read. “Okay who sent this in?”, one asks. “I think it was the same guy who sent in the one about the giant killer centipede, Arthro-something?” the other replied. With a sigh the first executive tosses the script onto a large pile in the corner.

Who needs alien monsters when prehistory keeps giving us animals to make movies about! First there was the giant creepy-crawlies of the Carboniferous, now this!

Hatzegopteryx (meaning “Hațeg basin wing”) was a wonder of the Late Cretaceous. It was first discovered only 17 years ago in 2002, and described from fragmentary remains of skull, humerus and femur. Initially these fossils were thought to belong to a large carnivorous dinosaur. However further study showed that they belonged to a flying reptile – a Pterosaur. Pterosaurs were a group of reptiles that dominated the skies during the Mesozoic era, going extinct sixty five million years ago at the end of the Cretaceous period. They had wings consisting of thin complex structures that stretched from their lower bodies to the end of an elongated fourth finger. Hatzegopteryx in particular belonged to the sub group of pterosaurs known as the azhdarchids. The azhdarchids appeared in the Late Cretaceous and grew to gigantic proportions even by pterosaur standards. They were the largest flying animals to ever live. Hatzegopteryx was no exception, with a wingspan of up to twelve metres long. Despite its large size (and some palaeontologists claiming that they had evolved to be flightless) such a large animal was able to fly because it was surprisingly lightweight. Even the largest azhdarchid pterosaurs have been estimated to weigh only 550 pounds. This is due to a combination of weight saving hollow bones and soft tissue air sacs, which also provided an oxygen reserve for powered flight. In flight azhdarchids such as Hatzegopteryx would have wasted little energy flapping, instead soaring on rising air currents like a modern day vulture. This allowed them to cover great distances, up to 10,000 miles in some estimates. Like almost all pterosaurs Hatzegopteryx would also likely have had a body covering of soft down known as pycnofibres. This down, while feather-like, was different to the feathers of birds and used in insulation rather than for display or flight.

Hatzegopteryx humorous bones from above (A) and from the side (B)
Image Credit: Mark Witton & Michael Habib, http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0013982

However despite being able to fly Hatzegopteryx would not have done its hunting whilst airborne. Instead, and rather unusually for a pterosaur, it hunted on the ground. When grounded Hatzegopteryx stood at a height of around five metres, which is as tall as a modern day giraffe! From this high vantage point Hatzegopteryx could survey the landscape, looking for any small dinosaurs it could catch. Able to comfortably stride across the landscape using all four limbs, Hatzegopteryx would pick up and swallow whole any small animals it could find while using its sharp beak to kill any larger individuals. Such a hunting strategy is not too dissimilar to that employed by modern day storks and hornbills, except on a much larger scale. Hatzegopteryx managed this hunting style because of its huge skull. At three metres long and half a metre wide it was the longest skull of any land based animal. This was a powerful beaked weapon that was supported by a relatively short but hugely muscular neck. This short neck is a relatively new discovery and stems from a 2017 paper written by Palaeontologists Mark Witton and Darren Naish. This skull and neck is different to other azhdarchids, such as Quetzelcoatlus and Cryodrakon, which tended to have longer necks and thinner skulls.

A 3 metre long skull of Hatzegopteryx (Top) compared with the 1.5 metre long skulls of Spinosaurus (Bottom right) and Giganotosaurus (bottom left)
Image Credit: Wikimedia Commons, https://commons.m.wikimedia.org/wiki/File:Skulls_length_comparison_of_Hatzegopteryx,_Spinosaurus_and_Giganotosaurus.png. Based on images from Therrien & Henderson 2007 and Buffetaut, Grigorescu & Csiki 2002.

Hatzegopteryx was first discovered in Transylvania in Romania, in the same area that Bran Stokers Dracula lived (though I’m sure Hatzegopteryx would have eaten Dracula for lunch then eyed up Van Helsing as seconds!). 70 million years ago this area was an island, roughly the size of Ireland, known as Hațeg Island. Hațeg was a subtropical environment, consisting of broadleaf forests, open plains and a hot climate. If it were around today it would be heaving with tourists – Hatzegopteryx permitting. What makes the island uniquely interesting were the dinosaurs that lived there. Consisting of a mix of sauropods, hadrosaurs and small theropods, they were of a smaller size compared to their mainland counterparts. For example Magyarosaurus dacus, a species of titanosaur sauropod, had a maximum length of only six metres on Hațeg, compared to fifteen metres on mainland species. This is equivalent to finding an elephant the size of a donkey and is an example of “insular dwarfism”. This is when animals on an isolated island adapt to the limited resources by growing to smaller sizes. Hatzegopteryx on the other hand is an example of “island gigantism”, where in order to fill an empty ecological niche (in this case the role of “top predator” – there were no large carnivorous dinosaurs on Hațeg) an animal grows larger than usual. A modern day counterpart to Hațeg Island would be the Galapagos Islands, where we see similar diverged island evolutionary processes (e.g. the giant tortoise and numerous species of finches). Another example would be New Zealand, where in the absence of large mammals birds such as the Kiwi, the Moa and the Haast Eagle evolving to occupy the major ecological niches (the latter two only going extinct within the last 1000 years).

Hatzegopteryx would have been a marvel to witness flying. An extraordinary and complex achievement of natural aeronautical engineering, there has never been an animal quite like it. If Hatzegopteryx was alive today I’m sure the reptile/stork/giraffe hybrid would generate the same (if not more) fear as another famous blood sucking Transylvanian does.

EDIT: By a weird coincidence 3 days after this blog went up a new paper came out by (Solomon et. al. 2019) about the discovery of a new species from azhdarcid pterosaur from Transylvania! Known from fragments of beak and vertebrae and thought to represent a juvenile this new pterosaur has been named Albadraco tharmisensis. It has been estimated to have been only a little bit smaller than Hatzegopteryx and further illustrates the wide range of life that was present on Hațeg Island 70 million years ago!

References/Further Reading

Solomon et. al. 2019 paper on the new azhdarchid pterosaur Albadraco, which lived at the same place and time as Hatzegopteryx.

Solomon, A. A., et al. (2020). “A new species of large-sized pterosaur from the Maastrichtian of Transylvania (Romania).” Cretaceous Research 110: 104316.

A paper by Darren Naish and Mark Witton (Naish & Witton 2017) on Hatzegopteryx neck length and biomechanics

Naish D, Witton MP. 2017. Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators. PeerJ 5:e2908 https://doi.org/10.7717/peerj.2908

A paper, written by a team led by Michael Benton (Benton et. al. 2010), on the dwarf dinosaurs of Haţeg Island.

Benton, M. J., et al. (2010). “Dinosaurs and the island rule: The dwarfed dinosaurs from Haţeg Island.” Palaeogeography, Palaeoclimatology, Palaeoecology 293(3): 438-454.

An article, written by Elizabeth Martin-Silverstone and published on The Conversation website, on Azdarchid Pterosaur flight.

Martin-Silverstone, Elizabeth, “Pterosaurs should have been too big to fly – so how did they manage it?”, The Conversation, Jun. 30, 2016, theconversation.com/pterosaurs-should-have-been-too-big-to-fly-so-how-did-they-manage-it-60892

Another interesting paper, Yang et. al. 2018, on Pterosaur’s feather-like pycnofibres

Yang, Z., Jiang, B., McNamara, M.E. et al. Pterosaur integumentary structures with complex feather-like branching. Nat Ecol Evol 3, 24–30 (2019). https://doi.org/10.1038/s41559-018-0728-7

Megalosaurus: The Original Dinosaur


An Artist reconstruction of Buckland’s great lizard
Image Credit: LadyofHats Mariana Ruiz, https://commons.m.wikimedia.org/wiki/File:Megalosaurus_dinosaur.png

There is no group of extinct life that enthrals the minds of the general public quite like dinosaurs. All palaeontologists both current and aspiring can claim to have at least been partially inspired by reading books and watching documentaries about dinosaurs, and from seeing their fossils and reconstructions in the many museums throughout the globe. Some dinosaurs have received vast amounts of media attention; the great Tyrannosaurus Rex; the three-horned Triceratops; and the long necked Brachiosaurus to name a few. However there is one dinosaur that can claim to be perhaps the most important of them all. Megalosaurus bucklandii is not as well-known as these other dinosaurs, which is quite surprising to me. However this medium-large sized theropod from the mid-Jurassic has every claim to live long in the history books.

Megalosaurus was the first dinosaur to be properly and scientifically described and the first animal to be referred to as a “dinosaur”. The first Megalosaurus fossils were discovered in the village of Stonesfield in Oxfordshire, England in the 18th century. These fossils came from a Mid-Jurassic (170-150 Million years old) deposit known as the “Stonesfield Slate”, a deposit that has also preserved the remains of other dinosaurs, pterosaurs, insects and plants of the time. The Megalosaurus fossils, originally described under the interesting name of Scrotum humanum, which was not formerly accepted by any scientific body, were passed on in 1824 to the geologist William Buckland, who in collaboration with the anatomist Georges Cuvier, identified the animal as a large extinct reptile. This animal was given the name Megalosaurus bucklandii, meaning “Buckland’s great lizard”. It was almost 20 years later in 1842 that Megalosaurus was referred to by Sir Richard Owen as a “dinosaur”. This discovery was quite unlike any living animal and captured the imagination of the Victorian public, with Megalosaurus making an appearance in the Charles Dickens novel Bleak House. This made it one of the first (but certainly not the last!) dinosaurs to appear in mainstream popular media.

A fossilised lower jaw and tooth of Megalosaurus. This jaw is one of the more iconic dinosaur fossils.
Image Credit: Wikimedia Commons, https://he.m.wikipedia.org/wiki/%D7%A7%D7%95%D7%91%D7%A5:Buckland,_Megalosaurus_jaw.jpg

Most of the Megalosaurus specimens that these early Victorian geologists had to go on were incomplete, with the only finds being a lower jaw, upper jaw, some teeth and a few thigh and leg bones. In addition this was really the first time anyone had attempted to reconstruct dinosaurs from their bones. So the Victorian scientists could only make educated guesses as to what this animal was like. While they knew, based on its tooth anatomy, that it was related to reptiles the first reconstructions of Megalosaurus were very different to what we believe today. Basing its design on modern lizards Megalosaurus was reconstructed as a massive, sluggish four legged animal, with its tail dragging along the ground and possessing a big hump on its shoulders. This interpretation can be seen in all its glory at the Crystal Palace Park in London. Unveiled in 1851 it is displayed stalking a group of equally lizard like Iguanodon, also inaccurate as Iguanodon would appear almost 40 million years after Megalosaurus (to name one inaccuracy!). It was only when further theropod remains were found a few decades later that a more accurate picture of Megalosaurus became clear. However during this time the Megalosaurus species was known as a “wastebasket taxon” where any newly discovered large theropod remains were all haphazardly lumped into the Megalosaur group, like somebody chucking different types of cutlery into the same drawer. Also the animal was portrayed, like other bipedal dinosaurs at the time, standing upright like a Kangaroo. This would only change nearly a whole century later, where research in the 1960s and 1970s led to all bipedal dinosaurs’ posture being altered to the more horizontally balanced forms seen today, where the head and body were counterbalanced by a long, lofted tail.

The Megalosaurus model at Crystal Palace park. This model, first revealed in 1851, shows us what Victorian Scientists thought it looked like.
Image Credit: Chris Sampson, https://commons.m.wikimedia.org/wiki/File:Crytsal_Palace_Megalosaurus.jpg

Whilst Megalosaurus has a long and important story about its discovery, and how it changed scientific thinking forever, what was this dinosaur actually like when it was alive? Well, Megalosaurus belonged to a group of theropods known as the Megalosauridae. This group were the main land predators of the early to mid-Jurassic period, dominating the landscape until their numbers declined during the late Jurassic 150 million years ago. Megalosaurus had many of the features that are typical of theropod dinosaurs; big hind legs, saurischian (lizard-like) hips, arms ending in non-pronated wrists, sharp claws and robust jaws filled with razor sharp teeth suitable for cutting and biting into the flesh of its prey. The powerful legs of Megalosaurus would have enabled it to reach speeds of up to 20 miles per hour, equivalent to a modern day Grizzly Bear and easily fast enough to chase down its prey. Once caught Megalosaurus would have attacked its prey with a powerful bite, its skull built for heavy impact by having a framework of slightly loose bones that, through flexing on impact were able to absorb the forces involved in biting and holding large struggling prey. Reaching up to nine metres long, three metres tall and weighing nearly one and a half tonnes it was the undisputed top predator of mid-Jurassic England, hunting large herbivorous dinosaurs, such as the long necked sauropod Cetiosaurus. However it would have needed to be an unfussy eater. During the Mid Jurassic, the UK was broken up into small islands, with Megalosaurus probably swimming from island to island and combing the beaches for any food it could find, including any marine reptiles, crabs and pterosaurs that had been beached. It is also possible, like a lot of other theropods, that Megalosaurus could have been at least partially feathered. Evidence for this comes from another megalosaurid called Sciurumimus. Found in the Late Jurassic of Germany this juvenile megalosaur was found preserved with a filamentous coating of feathers. While this isn’t direct evidence of feathers on Megalosaurus the fact that it is present on a close relative means that it is likely that it too possessed a similar coating, making it look a bit less like a scaly lizard and a bit more like a fluffy carnivorous bird. This new finding, put forward in a 2014 study by Rauhut et. al., would certainly have startled William Buckland, Richard Owen and the other Victorian scientists that first named this remarkable beast a “dinosaur”.

So, just as the 2008 film “Iron Man” was the start of the Marvel Cinematic Universe, and the Benz Patent Motor Car was the origin of today’s cars, the discovery of Megalosaurus was the genesis of dinosaur research. While T-Rex and others get the spotlight nowadays without this first description and reconstruction of this Mid-Jurassic Megalosaur from Oxford, dinosaurs would not have captured the public imagination in quite the way that they have. The field of palaeontology would perhaps have never evolved into the science it is today, and who knows, in that world I may have become an archaeologist!

References/Further Reading

Rauhut et al 2014 paper about feather filaments in the Megalosaur Sciurumimus

Rauhut, O. W. M., et al. (2012). “Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany.” Proceedings of the National Academy of Sciences 109(29): 11746-11751.

The Friends of Crystal Palace Dinosaurs page on the Megalosaurus model at Crystal Palace park, including comparisons with how the Victorian scientists thought it looked and behaved compared with modern interpretations

“Megalosaurus”, Friends of Crystal Palace Dinosaurs, cpdinosaurs.org/visit/statue-details/megalosaurus

More Information on Megalosaurus and other animals of the Stonesfield slate from the Oxford University Museum of Natural History website

“The Oxfordshire Dinosaurs”, Oxford University Museum of Natural History, oumnh.ox.ac.uk/megalosaurus-and-oxfordshire-dinosaurs

Get the all new Spinosaurus while stocks last!

The skeleton of an ancient river monster!
Image Credit: Mike Bowler, https://commons.m.wikimedia.org/wiki/File:Spinosaurus_swimming.jpg

Let me tell you a story. Three time travellers meet in a bar. They decide that they want to journey back to Mid Cretaceous North Africa, around 95 million years ago. They plan to have a dinosaur safari, just like the safaris that are conducted across the modern day Serengeti. However the area is dangerous as there are plenty of dangerous dinosaurs roaming around, some big enough to take out the jeep faster than the time travelling tourists can say “holy cow is that a dinosaur!” So they come up with a plan. Instead of going by jeep, they will use a river boat. “It’s perfect!” they say, “no dinosaur will be able to reach us as we are on the water and because it’s inland there’s no need to fear any sea faring marine reptiles”. After some time planning the time travellers undertake their boat journey. They marvel at the herds of the huge sauropod Paralititan and see an impressively large Carcharodontosaurus watching the herd hungrily. However as they are distracted by what they are seeing they don’t notice a large object moving in the river. Suddenly one of them hears the sound of rushing water and turns round to see a large sail poking out of the water like Jaws’ fin and heading right towards the boat. In five minutes, the time travellers will have seen their last dinosaur….

The unidentified river monster in this story is not a fish, nor a crocodile. It is instead the largest of all theropod dinosaurs: Spinosaurus aegyptiacus (meaning “Egyptian spine lizard”). The first Spinosaurus fossils were discovered in Egypt by German palaeontologist Ernst Stromer in 1912, however sadly these remains were destroyed during allied bombings raids on Munich during World War Two. Spinosaurus has gained more attention in recent years as new research has shown that this theropod had a lifestyle unlike any other dinosaur. The research suggests that Spinosaurus is the first known aquatic dinosaur.

There are certain anatomical features that support this interpretation. One area is the shape and design of the skull. The teeth were long and conical, well suited for gripping and holding on to slippery prey such as fish. The nostrils were placed high on its snout so it could hold it submerged in water while still being able to breath. It’s also thought that holes at the end of Spinosaurus’ snout contained pressure sensors, similar to those seen in modern crocodiles, which are used to detect disturbances in the water. The water based adaptations don’t stop there; one specimen of a Spinosaurus upper jaw has a barb embedded in it that belonged to a species of giant swordfish called Onchopristis. This suggests that Onchopristis was one of Spinosaurus‘ main sources of food. So taking all these adaptations together it suggests that Spinosaurus had a mostly fish based diet (however it is still possible that it ate meat as well).

An illustration of the head of Spinosaurus. Note the distinctive long, crocodile like jaws, conical teeth and small head crest.
Image Credit: Steveoc 86, https://commons.m.wikimedia.org/wiki/File:Spinosaurus_skull_steveoc.jpg

All these adaptations are well and good, however the biggest evidence for Spinosaurus‘ aquatic lifestyle was detailed in a paper released in 2014, written by a team of palaeontologists led by Spinosaurus expert Nizar Ibrahim. The paper examined and described a new 11.3 metre long specimen (that wasn’t fully grown, Spinosaurus could reach a maximum length of 15 metres) that is the most complete Spinosaurus skeleton ever found. Examination of the hind limb bones and pelvic girdle showed that they were much shorter than previously thought. These hind limbs were so short that Spinosaurus could not have walked on two legs for long periods of time as its legs couldn’t support its massive, front heavy bulk. This meant only one thing, Spinosaurus walked on all fours (at least occasionally). This is certainly very different to the bipedal, T-Rex killing beast that terrorised Alan Grant and the Kirbys in the 2001 film Jurassic Park 3. This new discovery also fits with the theory of a mostly aquatic based Spinosaurus. Short hind legs reduce drag when swimming and diving through water and is something that other aquatic and semi-aquatic animals, such as crocodiles and otters, exhibit today. These hind limbs were also solid and dense, helping with buoyancy control, and it has been speculated that feet would have been webbed to further aid in swimming. This means that Spinosaurus would have been comfortable and manoeuvrable in water, and a somewhat clumsy walker on land!

This reconstruction, which has commonly been dubbed “new Spinosaurus“, has caused quite a stir in the palaeontology community, Not everyone is on board with the idea and a few have even written articles and papers questioning the findings of the Ibrahim et al. 2014 paper. For example palaeontologist Scott Hartman questioned the length measurements of Spinosaurus’ hind limbs and Donald Hendersons 2018 paper questioned its buoyancy. However both these counter papers have their own issues; for example the Henderson paper based their buoyancy calculations on bone density data from other theropods and birds, except Spinosaurs have been shown to have proportionately thicker bones than these animals. The debate is still ongoing to this day, and so it is still not known for certain whether Spinosaurus truly was a quadruped or a biped.

So let us rejoice in the quadrupedal walking, gracefully swimming, humongously sized, sail-backed fish eater that Spinosaurus has become! Proof that during their 170 million year reign there were few habitats that the dinosaurs couldn’t reach.

UPDATE: Spinosaurus reconstructions continue to change with every new paper! A new study was published on the 29th April 2020 in the journal nature. Written by a team led by Nizar Ibrahim, has revealed that Spinosaurus had unusually tall neural spines and elongated chevrons on its tail vertebrae. These special vertebrae supported a flexible, paddle-like tail and it’s theorised that Spinosaurus used it to swim through the water! The image below illustrates what most palaeontologists now think Spinosaurus aegypticus looked like.

The most up to date (as of 29th April 2020) look of the river monster that our time travelling tourists had the misfortune of encountering!
Image Credit: Gustavo Monroy-Becerril, https://en.m.wikipedia.org/wiki/File:Spinosaurus_aegyptiacus_underwater.png

EDIT: One key piece of evidence, that I missed when writing this blog (my apologies!), from the Donald Henderson 2018 paper is that Spinosaurus’ centre of mass was located closer to its hips than to its torso. This is further evidence that Spinosaurus was a biped, walking on its short stubby legs (almost like a duck!). At the time of writing this Nizar Ibrahim has yet to publish his latest research on Spinosaurus so the two legged/four legged debate rages on. But currently the common consensus, at time of writing, is that Spinosaurus was a biped.

References/Further Reading

Ibrahim et al. 2014 paper, published in Nature, describing “New Spinosaurus

Ibrahim, N., et al. (2014). “Semiaquatic adaptations in a giant predatory dinosaur.” Science 345(6204): 1613-1616.

Henderson et. al. 2018 paper countering the Ibrahim et. al. 2014 paper

Henderson DM. 2018. A buoyancy, balance and stability challenge to the hypothesis of a semi-aquatic Spinosaurus Stromer, 1915 (Dinosauria: Theropoda) PeerJ 6:e5409 https://doi.org/10.7717/peerj.5409

Nizar Ibrahim’s response to Scott Hartman, published on Scott Hartman’s Skeletal Drawing.com.

Ibrahim et. al., “Aquatic Spinosaurus – The authors respond”, Scott Hartman’s Skeletal Drawing.com, Sept. 18, 2014, skeletaldrawing.com/home/aquatic-spinosaurus-the-authors-responsd9182014

An article in Smithsonian Magazine on the history of Spinosaurus research

Smithsonianmag.com, “Cracking the Code of Spinosaurus”, Smithsonian Magazine, Apr. 19, 2017, smithsonianmag.com/sponsored/spinosaurus-lost-dinosaur-paleontology-new-discovery-great-courses-plus-180962953/

New Ibrahim et. al. 2020 paper on the structure of Spinosaurus’ tail (USED FOR UPDATE)

Ibrahim, N., Maganuco, S., Dal Sasso, C. et al. Tail-propelled aquatic locomotion in a theropod dinosaur. Nature (2020). https://doi.org/10.1038/s41586-020-2190-3

Deinocheirus: The tale of the horrible hands

When I was a young boy who was madly into palaeontology and had significantly less adult responsibilities, I remember walking through the ever popular dinosaur exhibition in the Natural History Museum in London. Among the many displays, which ranged from models of dinosaur nests to the big skeleton of the Triceratops, there was one that always stood out to me. It was a pair of huge arms, complete with hands tipped with large claws. Unlike the proportionately tiny arms of Tyrannosaurus Rex, (I say proportionately as T-Rex arms were still as long as a humans) or the backwards facing stump like arms of Carnotaurus these arms were long with highly developed “hands”, displayed in such a way that it seemed like they could either give you a large hug or grab you and carry you away into the night. These arms, discovered in 1965, belonged to a dinosaur known as Deinocheirus mirificus; meaning “terrible hand which is unusual”. Quite a fitting description for a giant pair of arms! This beast lived in Mongolia 70 million years ago during the Late Cretaceous. At the time I first saw this fossil palaeontologists still didn’t really know what kind of dinosaur it was as no other fossils had been found except for the arms. It was a tricky task, how can you build up the image of an animal from just its arms. Imagine trying to construct what a human looked like, how we behaved, what we ate and what our social lives were like from just our arms. From this incredible looking fossil palaeontologists were able to deduce that it was a species of theropod dinosaur, but apart from that it was only guesswork.

That is, until new fossilised material was discovered in 2009 by a team from South Korea’s Institute of Geoscience and Mineral Resources in Kigam, lead by a palaeontologist named Yuong-Nam Lee. These were not only more giant arms, but also two nearly complete skeletons that finally solved the almost 50 year mystery.

It was much weirder than anything my younger self could have imagined. For starters, it was not a vicious giant carnivore like other large theropods such as Giganotosaurus. Instead it was an omnivore, using its duck-like beak to eat vegetation with a helping of small fish on the side. Deinocheirus was a slow, lumbering giant stretching to eleven metres in length, and weighing up to 6 tonnes. To add to the weirdness, it also possessed back spines that may have formed part of a hump like structure on its back, and it may also have even been covered in feathers. The end of its tail bones were fused together into a pygostyle. This same structure is seen today in modern birds and is used to support long tail feathers, so it’s possible that Deinocheirus also had a feathery tail fan! The large arms were probably used to gather out of reach plants closer to its mouth, rather like a giant panda grabbing bamboo, or as a defence against predators, such as the tyrannosaurid Tarbosaurus whose bite marks are seen on the bones. The fossils did confirm that it was a theropod dinosaur and part of the ornithomimids, a group of dinosaurs which also included Gallimimus of Late Cretaceous North America. However Deinocheirus is very bizarre even when compared to other ornithomimids. Other species were smaller, with slender bodies and legs built for speed (not too dissimilar in lifestyle to the modern day Ostrich).

So as it turns out, Deinocheirus is not the terrifying monster that I thought it was when I saw those fossil arms all those years ago. Instead, in looks and lifestyle, it seems like the result of a group of mad scientists genetically splicing a T-Rex, a duck and an ostrich together to see what they get. However this new depiction, in my view, is just as fascinating and awe inspiring, and shows how diverse dinosaurs really were.

The Horrible hands, along with the rest of Deinocheirus!
Image Credit: Johnson Mortimer, https://commons.m.wikimedia.org/wiki/File:Deinocheirus_by_johnson_mortimer-d9npnef.jpg

References/Further Reading

Lee et al 2014 paper, published in the journal Nature, describing new fossil material of Deinocheirus

Lee, Y., Barsbold, R., Currie, P. et al. Resolving the long-standing enigmas of a giant ornithomimosaur Deinocheirus mirificusNature 515, 257–260 (2014). https://doi.org/10.1038/nature13874

An article on National Geographic, written by Ed Yong, on the 2014 study of Deinocheirus that revealed its true form

Yong, Ed “Deinocheirus Exposed: Meet The Body Behind the Terrible Hand”, National Geographic, Oct. 22, 2014, nationalgeographic.com/science/phenomena/2014/10/22/deinocheirus-exposed-meet-the-body-behind-the-terrible-hand/

An article on NewScientist, written by Jeff Hecht, about the re-discovery of a fossil Deinocheirus‘ head and feet, which had been previously smuggled out of Mongolia!

Hecht, Jeff. “Stolen dinosaur head reveals weird hybrid species” NewScientist, May. 12, 2014, newscientist.com/article/dn25551-stolen-dinosaur-head-reveals-weird-hybrid-species/