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