Pelecanimimus joins the LRT

Yes, it is the basalmost ornithomimosaur,
(of three tested), but from whence did the theropod dinosaur, Pelecanimimus (Figs. 1-3), arise?

Figure 1. Rough tracing and reconstruction of Pelecanimimus based on low rez photos from 1994 paper.

Figure 1. Rough tracing and reconstruction of Pelecanimimus based on low rez photos from 1994 paper.

 

In the original paper
Pérez-Moreno et al. 1994 tested only Allosaurus, Albertosaurus, Deinonychus and Troodontidae in order of decreasing distance as outgroup taxa to Pelecanimimus + Ornithomimosauria using 22 characters. In the early days of PAUP this is all that most workers did back then… sort of testing the phylogenetic waters.

In a competing study
the large reptile tree (LRT) tests 1370+ taxa and recovers the holotype of Compsognathus as the proximal outgroup. In the same study members of the Troodontidae nest closer to birds (birds nest within the clade that includes some traditional troondontids, but not others).

Unique indeed…
The long down-curved jaws of Pelecanimimus are not found in either ancestral compsognathids nor descendant ornithomimosaurs. The wrist appears to be made of tiny bones, capable of minimal movement. ‘On the other hand’ the fingers are provided with large cylindrical joints for substantial flexion and extension.

Figure 2. DGS tracings from 1994 paper focusing on skull and manus of Pelecanimimus.

Figure 2. DGS tracings from 1994 paper focusing on skull and manus of Pelecanimimus.

A gular sac and cranial soft tissue are present
on the specimen. Not sure if we’re seeing radiating patterns of soft tissue aft of the ulna, or are those preparator chisel marks? Nothing glows in the UV image (Fig. 1), so let’s go with the latter.

Figure 4. Pelecanimimus to scale with Struthiomimus and Compsognathus.

Figure 3. Pelecanimimus to scale with Struthiomimus and Compsognathus.

References
Pérez-Moreno BP et al. (5 co-authors) 1994. A unique multi-toothed ornithomimosaur dinosaur from the Lower Cretaceous of Spain. Nature 370(4):363–367.

wiki/Pelecanimimus

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