Watercolor and pencil illustration of a juvenile Austriadactylus enthused for the discovery of a damselfly, while ants and a roly poly go on with their business in late triassic Austria.
I tried to be as precise as possible (while keeping a cute/cartoony style) in the reconstruction of this critter and took large inspiration from Fabrizio De Rossi's illustration on Pteros.com, adding only some little stripes to show its juvenile coat. I'm not sure about the environment and wether or not rolypolys were a thing... I read that plants in late Triassic were mainly conifers, and specificaly I tried to draw Aethophyllum stipulare, an herbaceous conifer plant.
I am not a naturalist tho, just an amateur, so if you have any criticism I'll gladly take it!
Time and Place: Between 227 and 208 million years ago, in the Norian of the Late Triassic
Eudimorphodon is only known from Italy.
Physical Description: There is only one specimen of Eudimorphodon ranzii known so far, but it’s a pretty complete one. It reveals a relatively small-headed, long-tailed pterosaur with a wingspan of only a meter. The head is triangular, with a pointy snout, and has a large eye socket. The nares (nose opening) were distinct from the antorbital fenestrae, a distinguishing feature of early pterosaur skulls. The two halves of the lower jaw were unfused, allowing some side-to-side widening.
The most interesting feature about Eudimorphodon is its teeth. Most pterosaurs have teeth that are all the same shape throughout the jaw, and in most cases they’re all simple, conical, and pointy. The two big exceptions in later pterosaurs are istiodactylids, which have serrated teeth, and dsungaripterids, which have these chunky bulbous teeth that deserve an article themselves. Triassic pterosaurs are different, however, in that they have multiple types of teeth in the jaw. Eudimorphodon’s name hints at this - there are conical fang-like teeth and pointy serrated teeth. The serrated teeth have three or five cusps, a larger one in the middle and one or two about half the size in front and behind. Each jaw has a few widely-spaced fang-like teeth at the front and a row of closely-spaced serrated teeth in the back. The serrated teeth are so closely spaced they’re straight-up touching - a rarity for pterosaur teeth. There upper jaw has two teeth in particular, about halfway back the serrated row, that are inexplicably huge. Yeah. Early pterosaur teeth are weird.
The rest of the body was pretty typical for an early pterosaur, from what we can tell. The arms have very robust humeri, with greatly expanded humeri, which would have supported very chunky arm muscles. The only specimen of Eudimorphodon doesn’t preserve most of the wing finger, but going off related pterosaurs they would have been ridiculously long; Campylognathoides had one of the if not the longest wing-finger-to-body-length ratios of any pterosaur. The legs were much narrower in the arms, but definitely not on the small side for pterosaurs. The tail isn’t preserved either, but it was probably much longer than the rest of the body and held stiff by elongate rods on each of the vertebrae.
Diet: Fish scales in the stomach of the holotype show that Eudimorphodon was a piscivore. The fang-like teeth at the front would have been used to grab fish from the water, and the rows of serrated teeth in the back formed a continuous cutting surface that would have been good for cutting through tough fish scales. Wear on the teeth and reconstructed skull musculature indicate that Eudimorphodon would have chewed its food. This is another noteworthy feature of Triassic pterosaurs - later pterosaurs simply swallowed food whole.
Behavior: The wings of pterosaurs around this part of the family tree indicate some form of specialized flight. The robust arms and narrow wings would have allowed for powerful flapping and high agility in the air, almost similar to birds of prey such as falcons. But it was no slouch on the ground either. The fingers have tiny little bones next to the claws called antungual sesamoids, which indicate that Eudimorphodon spent a good amount of time walking around on the ground. Given you can’t really land on the ground when you’re out fishing, it may have thus frequently roosted on the ground, or even in trees.
Ecosystem: At the time Europe was a series of islands, so Eudimorphodon probably fished out at sea and roosted in coastal forests. It would have shared the coastline with fellow early pterosaurs Peteinosaurus and Carniadactylus, as well as the tanystropheid Langobardisaurus. Further inland lived the pseduuchian Aetosaurus, the rhynchocephalian Diphydontosaurus, and drepanosaurs such as Vallesaurus, Megalancosaurus, and Drepanosaurus. Out at sea lived fish, the phytosaur Mystriosuchus, and the placodont Psephoderma.
Other: The type specimens of Arcticodactylus, Austriadraco, Carniadactylus, and Seazzadactylus were all formerly referred to Eudimorphodon at some point, some of them even considered specimens of E. ranzii. All of these are Triassic pterosaurs from Europe, and would have looked very similar in life. A recent phylogenetic analysis by Fabio Marco Dalla Vecchia found these four to be closer to Caviramus and Raeticodactylus than Eudimorphodon itself. Eudimorphodon turned out to be the most derived Triassic pterosaur, which makes sense given its similarity to Campylognathoides, one of the most basal Jurassic pterosaurs.
~ By Henry Thomas
Sources under the Cut
Dalla Vecchia, F.M. 2019. Seazzadactylus venieri gen. et sp. nov., a new pterosaur (Diapsida: Pterosauria) from the Upper Triassic (Norian) of northeastern Italy. PeerJ 7: e7363.
Ősi, A. 2011. Feeding-related charcters in basal pterosaurs: implications for jaw mechanism, dental function and diet. Lethaia 44 (2): 136-152.
Wild, R. 1978. Die Fugsaurier (Reptilia, Pterosauria) aus der Oberen Trias von Cene bei Bergamo, Italien. Bolletino della Societa Paleontologica Italiana 17: 176-256.
