Mesadactylus

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, Kimmeridgian–Tithonian PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Order:	†Pterosauria
Family:	†Anurognathidae
Genus:	†Mesadactylus Jensen & Padian, 1989
Species:	†M. ornithosphyos
Binomial name
†Mesadactylus ornithosphyos Jensen & Padian, 1989

Classification

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]

See also

• List of pterosaur genera
• Timeline of pterosaur research