Liaoxipterus

In 2005 Paleontologists Dong Zhiming and Lü Junchang named Liaoxipterus brachyognathus, an istiodactylid pterosaur from the Lower Cretaceous Jiufotang Formation. Liaoxipterus is known from a single lower jaw that was discovered in rocks at Chaoyang City, Liaoning, northeastern China. The generic name honors Liaoxi, a former province that made up the western part of modern Liaoning. The specific name, brachyognathus, translates to “short jaw,” pointing out that Liaoxipterus has proportionally shorter jaws than most other pterosaurs. 

The bones and teeth of the lower jaws are preserved on a slab of rock and are visible on their upper surface only. They are largely complete, but both the left and right sides are missing their rear-most ends including the articulation with the rest of the skull. They measure about 14 cm (5.5 inches) long, but would have probably been about 16 cm (6 inches) long when complete. They are roughly U-shaped when seen from above, with a very slight spoon-like expansion behind the broad rounded tips. 

There are 11 pairs of teeth packed into the front-most 4 cm (1.5 inches) of the jaws. They are short, stout cones directed slightly outward. The remainder of the jaws are completely toothless. No other material of Liaoxipterus is known, but comparison to other istiodactylids suggest that its head would have looked superficially duck-like and would have been roughly 20 cm (8 inches) long. If its body proportions were like those of other istiodactylids, Liaoxipterus would have had a wingspan of about 1.2 m (4 feet), about the same size as most geese. 

When Dong and Lü first described Liaoxipterus in 2005, they considered it to be an unusual ctenochasmatid because of its outwardly directed teeth and spoon-like expansion. Several other authors quickly pointed out that Liaoxipterus was quite dissimilar to other ctenochasmatids which have extremely long and narrow jaws lined with dozens to hundreds of needle-like teeth. On the other hand, Liaoxipterus is very similar to Istiodactylus and other istiodactylids which have U-shaped jaws with stout teeth limited to their tips. Subsequent phylogenetic analyses have shown that Liaoxipterus is indeed, an istiodactylid. 

Lioaxipterus lived about 120 million years ago and is known from rocks deposited in a temperate forest with many rivers, lakes, and swampy areas. Istiodactylids were carnivorous, and may have focused on small terrestrial prey or carrion. It’s likely that Liaoxipterus had similar habits.