First pterosaur basihyal (Gladocephaloideus?, Gallodactylidae?)

Jiang, Li, Cheng and Wang 2020 bring us
the first evidence of a tiny medial hyoid bone, the basihyal (Fig.1; IVPP V 14189). Comparisons were made to “scavenger crows rather than chameleons.” Other pterosaurs have hyoids, but, until now, not a basihyal. Really, that’s all the authors needed to say. The rest of what they presented was filler, little of it accurate or valid.

Figure 1. Images from Zheng et al. 2020 scaled, rotated and layered. This is all that is known of this specimen. Micro -CL image shows hollow basihyal.

Figure 1. Images from Jiang et al. 2020 scaled, rotated and layered. This is all that is known of this specimen. Micro -CL image shows hollow basihyal.

Overlooked by the authors,
Cosesaurus (Fig. 2), Sharovipteryx, Kyrgyzsaurus and Longisquama also have hyoids  The authors considered their specimen close to Gladocephaloideus (Fig. 3), which they considered a gallodactylid. Here Gladocephaloides nests with Gegepterus, a ctenochasmatid.

Figure 2. Cosesaurus nasal crest (in yellow).

Figure 2. Cosesaurus hyoids in bright green.

Jiang et al. 2020 presented a greatly simplified cladogram
of pterosaur interrelationships… so simplified that it bears little resemblance to a more complete pterosaur cladogram. Kryptodrakon (junior synonym for Sericipterus) was misspelled Kryptondrakon.

Figure 1. Gladocephaloideus (the holotype) compared to the new specimen referred to Gladocephaloideus and its two sister taxa in the large pterosaur tree. Long necks in ctenochasmatids made several appearances by convergence.  Of particular interest, note the size of the pelvis in the JPM specimen, no larger than that of the much smaller MB.R. specimen. Lü et al considered the pelvis incomplete and it may be. Sister taxa are illustrated here from figure 2.

Figure 3. Gladocephaloideus (the holotype) compared to the new specimen referred to Gladocephaloideus and its two sister taxa in the large pterosaur tree. Long necks in ctenochasmatids made several appearances by convergence.  Of particular interest, note the size of the pelvis in the JPM specimen, no larger than that of the much smaller MB.R. specimen. Lü et al considered the pelvis incomplete and it may be. Sister taxa are illustrated here from figure 2.

According to Jiang et al.
“The hyoids of primitive non-pterodactyloids only include the preserved ceratobranchials; this rod-like element is slender and quite long relative to the skull length. The ceratobranchial/skull length ratio is similar to most extant reptiles.” OK. Good to know.


References
Jiang S-X, Li Z-H, Cheng X and Wang X-L 2020. The first pterosaur basihyal, shedding light on the evolution and function of pterosaur hyoid apparatuses. DOI 10.7717/peerj.8292

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