A complex hyobranchial apparatus in a Cretaceous dinosaur and the antiquity of avian paraglossalia

Robert V. Hill, Michael D. D'Emic, Gaberiel Bever, Mark A. Norell

Research output: Contribution to journalArticle

Abstract

The highly specialized feeding apparatus of modern birds is characterized in part by paraglossalia, triangular bones or cartilages in the tongue that constitute part of the rarely fossilized hyobranchial apparatus. Here, we report on a new, juvenile specimen of the ankylosaurid dinosaur Pinacosaurus grangeri Gilmore, 1933 that provides the first evidence of paraglossalia outside of crown group Aves. The specimen is remarkable in preserving a well-ossified hyobranchial apparatus, including paired paraglossalia, first and second ceratobranchials, epibranchials, and evidence of a median cartilaginous basihyal. Reassessment of Edmontonia, another ankylosaur, also reveals evidence of bony paraglossalia. Ankylosaur paraglossalia closely resemble those of birds, but are relatively larger and bear prominent muscle scars, supporting the hypothesis that ankylosaurs had fleshy, muscular tongues. The other hyobranchial elements, surprisingly, resemble those of terrestrially feeding salamanders. Ankylosaurs had reduced, slowly replacing teeth, as evidenced from dental histology, suggesting that they relied greatly on their tongues and hyobranchia for feeding. Some curved, rod-like elements of other dinosaur hyobranchia are reinterpreted as second ceratobranchials, rather than first ceratobranchials as commonly construed. Ankylosaurs provide rare fossil evidence of deep homology in vertebrate branchial arches and expose severe biases against the preservation and collection of the hyobranchial apparatus. In light of these biases, we hypothesize that paraglossalia were present in the common ancestor of Dinosauria, indicating that some structures of the highly derived avian feeding apparatus were in place by the Triassic Period.

Original languageEnglish (US)
Pages (from-to)892-909
Number of pages18
JournalZoological Journal of the Linnean Society
Volume175
Issue number4
DOIs
StatePublished - Dec 1 2015
Externally publishedYes

Fingerprint

dinosaur
tongue
Cretaceous
teeth
birds
Aves
bird
salamanders and newts
cartilage
histology
ancestry
common ancestry
fossils
homology
vertebrates
arch
bones
tooth
bone
muscles

Keywords

  • Ankylosauria
  • Birds
  • Dinosauria
  • Hyobranchial apparatus
  • Paraglossal bone

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology

Cite this

A complex hyobranchial apparatus in a Cretaceous dinosaur and the antiquity of avian paraglossalia. / Hill, Robert V.; D'Emic, Michael D.; Bever, Gaberiel; Norell, Mark A.

In: Zoological Journal of the Linnean Society, Vol. 175, No. 4, 01.12.2015, p. 892-909.

Research output: Contribution to journalArticle

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