Mesadactylus ('mesa finger') is an extinct genus of pterosaur from the Kimmeridgian-Tithonian-age Upper Jurassic Morrison Formation of Colorado, United States. The genus was named in 1989 by James Jensen and Kevin Padian. The type species is Mesadactylus ornithosphyos.
Mesadactylus Temporal range: Late Jurassic,
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Order: | †Pterosauria |
Family: | †Anurognathidae |
Genus: | †Mesadactylus Jensen & Padian, 1989 |
Species: | †M. ornithosphyos
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Binomial name | |
†Mesadactylus ornithosphyos Jensen & Padian, 1989
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The holotype is BYU 2024, a synsacrum of seven sacral vertebrae, featuring a unique—for a pterosaur—complete fusion of the spinae into a supraneural blade, a character, as the specific name indicates more typical for birds, at first leading Jensen to assign the fossil to a bird, Palaeopteryx.
Further referred associated remains include arms bones, pectoral girdle bones, vertebrae (including cervix and sacral), and femora.[1] Additional material was described in 2004 (including a partial braincase)[2] and 2006; in the latter publication, the authors suggested that its larger contemporary Kepodactylus could be the same animal, although there are minor differences.[3][4]
Jensen and Padian classified Mesadactylus as a pterodactyloid. In 2007 S. Christopher Bennett claimed that the holotype and the referred material came from different forms and that, while the last was indeed of a pterodactyloid nature, the synsacrum belonged to a member of the Anurognathidae.[5]