Microtuban

Description

In 2011 paleontologists Ross Elgin and Eberhard Frey named Lebanon's second known pterosaur, Microtuban altivolans. Microtuban was found near Hjoûla in in the Sannine Formation, in rocks deposited at the beginning of the Late Cretaceous, approximately 100 million years ago. 

Microtuban is known from a single partial specimen, made up of some neck vertebrae, portions of the shoulders, a portion of the right wing, the complete left wing, and fragments of the hindlimb. The proportions of the bones in the wing finger are unique in Microtuban, and differentiate it from all other pterosaurs. Specifically, the last phalanx is extremely short, making up only about 1% of the total length of the finger. The last phalanx is strongly curved, with its tip pointing toward the rear edge of the wing. This would have given the end of the wing a curved edge, rather than a point. The specimen is quite small; in life the animal had a wing span under 1.5 meters (5 feet). Elgin and Frey noted that this specimen was not fully grown based on its bone texture and unfused sutures. 

The authors compared Microtuban to other pterosaurs to determine its closest relatives. The long narrow hand present in Microtuban indicates that it is a member of the short-tailed pterosaur group, the pterodactyloids. Additional features indicate that it is a member of the Azhdarchoidea, a group of mostly toothless terrestrial carnivores or omnivores. The Azhdarchoidea include the tapajarids, Thalassodromids, Chaoyangopterids, and Azhdarchids. Elgin and Frey could eliminate Microtuban from the azhdarchids and tapejarids, but not from the chaoyangopterids or thalassodromines. Both families have long skulls with straight toothless jaws, and oftentimes bore tall narrow crests that stretched above and behind the eye. It is likely that Microtuban was similar.