Tianyuraptor: another basal tyrannosaur/derived compsognathid

Earlier we looked at Zhenyuanlong (Lü and Brusatte 2015), a purported dromaeosaurid that nested in the large reptile tree between Compsognathus and Tyrannosaurus. Zhenyuanlong was considered close to Tianyuraptor ostromi (Zheng et al. 2010), so I had to check it out.

After tracing and reconstruction
(Figs. 1-4), in the large reptile tree Tianyuraptor nests between Compsognathus and Zhenyuanlong, all basal to T-rex. Like Compsognathus, Tianyuraptor has an orbit that is as wide as tall. Tianyuraptor also has a longer ‘Compy‘ torso.

Figure 1. Tianyuraptor nests between Compsognathus and Zhenyuanlong in the large reptile tree. Both are from Early Cretaceous China.

Figure 1. Tianyuraptor nests between Compsognathus and Zhenyuanlong in the large reptile tree. Both are from Early Cretaceous China. Neither are dromaesaurs. They are basalmost tyrannosaurs.

As before
the reconstruction of Tianyuraptor was created using DGS (digital graphic segregation).

Figure 2. Tianyuraptor in situ. DGS colors identify vertebrae, limbs, skull, etc. Feathers were not identified in this fossil, but this specimen likely had them.

Figure 2. Tianyuraptor in situ. DGS colors identify vertebrae, limbs, skull, etc. Feathers were not identified in this fossil, but this specimen likely had them.

Similarly
the skull was reconstructed (Fig. 3) rom color tracings (Fig. 4).

Figure 3. Tianyuraptor reconstruction from colorized elements traced from the fossil image (figure 4).

Figure 3. Tianyuraptor reconstruction from colorized elements traced from the fossil image (figure 4).

Figure 4. Tianyuraptor skull in situ traced in color to help identify broken elements.

Figure 4. Tianyuraptor skull in situ traced in color to help identify broken elements. These are restored to their in vivo positions in figure 3. Note the hourglass-shaped quadratojugal, similar to that of T-rex.

And finally
these taxa all have a distinct postfrontal (Fig. 5). Dinosaurs are supposed to fuse that bone to the frontal or postorbital, but in this clade, as in the bird clade, fusion of the postfrontal did not always happen.

Figure 5. Tyrannosaur postfrontal identified. I hate to point out the obvious, but this is simple observation, not distorted by paradigm.

Figure 5. Tyrannosaur postfrontal identified. I hate to point out the obvious, but this is simple observation, not distorted by paradigm.

References
Lü J and Brusatte SL 2015. A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution. Scientific Reports 5, 11775; doi: 10.1038/srep11775.
Zheng X-T; Xu X; You H-L; Zhao, Qi; Dong Z 2010. A short-armed dromaeosaurid from the Jehol Group of China with implications for early dromaeosaurid evolution. Proceedings of the Royal Society B 277 (1679): 211–217.

 

 

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