It’s strange now to think how difficult it once was to dig up information. Growing up, I couldn’t just sit in my family room and browse through scientific papers. Basic research required a trip to the public library. Serious research required a trip to the University of Delaware library. Mostly, though, I relied on a set of c. 1960 World Book Encyclopedias I inherited from my great grandmother. Now there’s the internet.
This is a long way of saying that there’s a lot about Delaware I can easily learn now that I had essentially no way of knowing then.
For example, I never knew there was a fossiliferous Cretaceous formation accessible about ten miles from the house I grew up in.
And I definitely never knew that pterosaur remains had been recovered from this formation.
Modern rendering of the azhdarchid pterosaur Quetzalcoatlus, courtesy of Witton & Naish 2008.
The Chesapeake and Delaware canal runs across a narrow strip of Delaware and Maryland, connecting the Delaware River to the Chesapeake Bay via the Elk River, a Chesapeake tributary. In the 1960s and 1970s, the canal’s muddy banks were accessible, and dredged material from the canal was dumped in heaps on the canal’s north side. The sediments along the banks and in the heaps were rich in fossils (in fact, I just learned that my mom used to go fossil hunting with my grandfather there).
In the early 1970s, a vertebra, humerus, femur, and tibia were recovered from these sediment heaps. A 1981 paper by Baird and Galton identified these bones as pterosaur remains in part because they were “extremely insubstantial,” with a “paper-thin” outer layer and “pneumatic cavities” inside the bone. Beyond that, though, the authors declared more specific identification of the specimens “fraught with uncertainty” — their best guess was Pteranodon.
In 1994, Bennett tentatively agreed that the bones were likely Pteranodon: “A short midcervical vertebra of a large pteranodontid (the only large short necked pterosaurs known in the Upper Cretaceous) and other pterosaur fragments are known from the Merchantville Formation (early Campanian) of Delaware (Baird and Galton, 1981). These materials are identified tentatively as Pteranodon.”
But in 2008, Averianov, Arkhangelsky, and Pervushov called the Delaware pterosaur’s identification as Pteranodon into question: “The incomplete cervical vertebra of a pterosaur from the Campanian of Delaware, United States, that was referred to Ornithocheiridae (Baird and Galton, 1981, text-ﬁg. 2), is almost identical to specimen SGU, no. 47/104a and could have been cervical vertebra 3 of an azhdarchid.” Ornithocheiridae, by the way, is the family that houses Pteranodon.
Now there seems to be an implicit debate: a 2010 paper by Averianov definitively identifies the Delaware remains as those of an azhdarchid, while a 2011 paper by Sullivan and Fowler attributes the remains to the family Ornithocheiridae. I don’t know enough to take sides, but I’m rooting for an azhdarchid.
Pteranodon is fine and all — it’s impressive in its way, and certainly iconic. But the azhdarchids were much more tremendously impressive. Here’s a quick-hit recap of azhdarchid morphology from Witton and Naish (2008): “All azhdarchids exhibit large skulls …, elongate, cylindrical cervical vertebrae, proportionally short wings …, and elongate hindlimbs. These anatomical features, combined with the large size of some taxa, make azhdarchids one of the most striking and distinctive pterosaur groups.” Striking and distinctive is perhaps an understatement. Alien-looking azhdarchids could reach approximately 20 feet in height, with 35-foot wingspans. Wow.
This image just a bout sums up the ornithocheirid versus azhdarchid competition:
Pteranodon, Homo sapiens, and the azhdarchid Hatzegopteryx, courtesy of Mark Witton via Flickr.
And that’s just basic morphology. Ecology actually bumps azhdarchids up a notch on the impressive scale.
Witton and Naish (2008) have demonstrated convincingly that azhdarchids were probably “terrestrial stalkers,” roaming field and forest on foot while snacking on “small
vertebrates and large invertebrates, possibly supplemented with fruit and carrion.” Bear in mind that these are 20-foot-tall beasts with beaks as big as entire people — to them, we may well have been snackable “small vertebrates.”
Earlier this year, Averianov apparently challenged Witton and Naish’s terrestrial-stalking hypothesis in part because, he said, azhdarchids would have been vulnerable to predation on the ground — these mighty beasts might themselves have been T. rex snacks. But Witton and Naish quickly responded [pdf] in another 2013 article,* noting that some azhdarchids were actually taller than the largest theropods and possessed intimidating (or weird) enough features that T. rex and its cousins likely would have sought out easier prey. In fact, even if a tyrannosaur had targeted a large azhdarchid, the pterosaur might well have been able to hold its own. Witton and Naish note that “azhdarchid like rostra [beaks] are dangerous weapons in some circumstances,” and they compare azhdarchids to some modern storks known “to repeatedly stab human attackers when provoked.” (Side note: I’ve seen one of the storks referenced — the Jabiru — and it’s an impressive bird indeed.) Not to mention that if the azhdarchid didn’t feel like fighting back, it could have used its quadrupedal-launch capabilities to flee rapidly into the air. Again, wow.
All of which is to say that if the Delwarean pterosaur specimen is in fact an azhdarchid, it may well be the coolest thing from Delaware ever.
* If you don’t want to tackle the paper itself, you can read more about these 2013 azhdarchid papers in this post on Darren Naish’s tetrapod zoology blog. Given their disagreements with Averianov over azhdarchids, I wonder how Witton and Naish would classify the Delaware pterosaur?
D. Baird and P. M. Galton (1981) Pterosaur Bones from the Upper Cretaceous of Delaware. J. Vertebr. Paleontol. 1 (1), 67–71.
Bennett, C. (1994) Taxonomy and systematics of the Late Cretaceous pterosaur Pteranodon (Pterosauria, Pterodactyloidea): University of Kansas Museum of Natural, Occasional Papers, n. 169, p. 1-70. [Link]
Averianov, A., Arkhangelsky, M., and Pervushov, E. (2008) A New Late Cretaceous Azhdarchid (Pterosauria, Azhdarchidae) from the Volga Region”. Paleontological Journal 42 (6): 634–642. doi:10.1134/S0031030108060099 [Link]
Witton, M. and Naish, D. (2008) A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology. PLoS ONE 3(5): e2271. doi:10.1371/journal.pone.0002271.
Averianov, A. (2010) The osteology of Azhdarcho lancicollis Nessov, 1984 (Pterosauria, Azhdarchidae) from the Late Cretaceous of Uzbekistan. Proceedings of the Zoological Institute RAS 314, 264–317 [Link]
Averianov, A. (2013) Reconstruction of the neck of Azhdarcho lancicollis and lifestyle of azhdarchids (Pterosauria, Azhdarchidae). Paleontological Journal 47:203-209.