Besides Yunmenglong, which was discussed in my last post, a few more dinosaurs have turned up this year. They’re actually pretty interesting, and are listed as follows.
Jianchangosaurus yixianensis:This dinosaur, known from a juvenile specimen, is the latest feathered dinosaur to come out of China’s famous Yixian Formation. It is a basal therizinosaur that has a dental arrangement reminiscent of ornithopods and ceratopsians. Since Jianchangosaurus is the most complete therizinosaur known so far, it makes sense that it sheds light on the morphological gap observed between Falcarius and Beipaiosaurus, its two closest known relatives. As a Chinese therizinosaur that looks like the North American dinosaur Falcarius, Jianchangosaurus also proves the wide distribution of therizinosaurs during the Early Cretaceous period.
Aurornis xui:This creature, hailing from the Middle Jurassic of China, is described as an avialan dinosaur more primitive than even Archaeopteryx, the reputed ‘first bird,’ which it predates by 10 million years. It’s from the Tiaojishan Formation, a place also home to Tianyulong, Anchiornis, and other well-preserved dinosaurs. Aurornis’s bone structure is more primitive than that of Archaeopteryx, and the absence of larger feathers suggests that it was unable to fly or even glide. Based on about 15,000 anatomical characteristics, Aurornis is the most primitive confirmed avialan thus known. However, exactly what we should call Aurornis in less technical terms is unclear, since it represents one phase of a great transition. The line between bird and dinosaur used to be clear, but new remains blur that line so significantly that the terms ‘bird’ and ‘dinosaur’ are really hard to define. Whatever the case, Aurornis is an important find and helps trace the evolution of birds.
Bravoceratops polyphemus: The only ornithischian in this edition of New 2013 Stuff is a chasmosaurine ceratopsian. Hailing from the Early Maastrichtian stage of Texas, this animal shares characteristics with the famous Torosaurus and Triceratops. It has a combination of primitive and derived characteristics, which not only suggests a relationship with Triceratops and co., but also with Coahuilaceratops, another transitional chasmosaurine (however, it lived in Mexico, not Texas). Like Coahuilaceratops, Bravoceratops follows a trend of some chasmosaurines in North America; a trend of changing into Triceratops-like forms.
I hope you enjoyed this issue of New 2013 Stuff. Once more discoveries are unveiled, expect to see another update!