In 1986 Eugen Kessler and Tiberiu Jurcsák gave the name Eurolimnornis corneti to a fragment of a right humerus discovered in the Lower Cretaceous Cornet Locality in northwestern Romania. Kessler and Jurcsák thought the humerus belonged to an archaic grebe, which explains the generic name, meaning “European lake bird” in Greek. Subsequent research has cast doubt on its identity as a grebe or as a bird at all. A 2012 paper by Federico Agnolin and David Varricchio pointed out that the humerus of Eurolimnornis has several features found only in pterosaurs and not in birds.
The specimen is made up of the distal portion of a right humerus, measuring about 2 cm (3/4 inch) long, by 1.3 cm (1/2 inch) wide. Among the pterosaurian features mentioned by Agnolin and Varricchio are a deep and elongate brachial depression with poorly defined edges, a wide and deep depression at the elbow not bound by a ridge, a deep pneumatic foramen above the distal condyles, as well as a wide pneumatic foramen behind the distal condyles, and a trochlea with groove.
When complete, the humerus was probably 6-8 cm (2.5-3 inches) long. The humeral shaft is oval in cross section, but flattens and widens nearer to the elbow. Eurolimnornis was a small pterosaur, with a wingspan probably close to 1 meter (39 inches).
Agnolin and Varricchio didn’t assign Eurolimnornis to any particular lineage due to its incomplete nature. They note that it lacks features present in ornithocheiroids and azhdarchoids, so was probably not a member of either group. At Pteros, we have reconstructed Eurolimnornis as an archaeopterodactyloid similar to Ctenochasma, as archaeopterodactyloids were the third major lineage of pterosaurs present in the Early Cretaceous. Further finds will help us refine our understanding of its place in the pterosaur family tree.
Eurolimnornis lived about 143 million years ago on one of several large islands that made up Europe during most of the Mesozoic Era. At the time, Romania was much further to the south and had a tropical to subtropical climate. The fossils of Eurolimnornis and several other animals found at the site were actually deposited in an ancient limestone cave that was completely filled with sediment over time and then eroded many tens of millions of years later.