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Aurornis (pre-bird) skull, traced using DGS
Aurornis xui (Godefroit et al. 2013, Late Jurassic, 50cm in length, 160 or 125mya) is one of the few outgroup taxa known for Archaeopteryx and the birds. (Balaur is another in the large reptile tree).
Auronis is a small, gracile dromaeosaur
without a large elevated pedal digit 2. The skull is complete, but slightly disarticulated (Fig. 1). A little DGS colorizes the bones. These can then be reassembled to form a skull in lateral view.
Fig. 1 Aurornis skull in situ, various elements segregated from the in situ fossil and reassembled into a complete and articulated skull. Only the easy bones are colorized here, leaving others uncolored. No doubt there are some errors here. I had only a medium resolution image and my knowledge of dinosaur skulls is still at the freshman stage. The hole in the surangular is an artifact. The little lavender ovals are displaced sclerotic bones.
Like many other small theropods,
Aurornis was feathered, agile and fast, a descendant of basal dromaeosaurids, like Halplocheirus. In palatal view, the internal nares are located on the anterior palatines and the anterior palate is narrow but solid. The premaxilla is still relatively short and toothed. The pterygoids are narrow and have lost their primitive triangular shape. As a result of taphonomy, tracings for the anterior dentary teeth are distinct from one another. The wider, more typical, pointed teeth are the correct morphology.
Figure 2. Aurornis in several views alongside Archaeoperyx to scale.
On a side note:
Pappochelys (‘grandfather turtle’) has been getting a lot of press, none critical. Take a fresh look at all the PR here.
On another side note:
Chilesaurus, which the large reptile tree nested as the long sought and current most basal member of the Ornithischia, and we looked at earlier here, was given a good look over at the TheropodDatabase blog here. Evidently others also think the original Chilesaurus report has issues.
References
Godefroit P, Cau A, Hu D-Y, Escuillié, Wu, W-H and Dyke G 201. A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds. Nature 498 (7454): 359–362.
Source: https://pterosaurheresies.wordpress.com/2015/06/30/aurornis-pre-bird-skull-traced-using-dgs/
