Oromycter was a small caseid characterized by its dentition, which lacked the distinct leaf-like serrations of other caseids and instead possessed broad, spatulate and roughened cutting edges. Its teeth were also more thoroughly attached to the bone of the skull and jaw than in other members of Caseidae. The first and second teeth of the premaxilla show distinct wear facets which suggest that they occluded with the first and second teeth of the dentary, possibly to facilitate the cropping of vegetation. Its lacrimal bone, while clearly caseid in form, appears more primitive than in any other known caseid.[1]
Classification
Oromycter is the oldest and most basal caseid known, and is the sister taxon of all other caseids.
Below is a cladogram based on the phylogenetic analysis of Maddin et al. in 2008.[3]
^Maddin, Hillary C.; Sidor, Christian A.; Reisz, Robert R. (2008-03-12). "Cranial anatomy of Ennatosaurus tecton (Synapsida: Caseidae) from the Middle Permian of Russia and the evolutionary relationships of Caseidae". Journal of Vertebrate Paleontology. 28 (1): 160–180. doi:10.1671/0272-4634(2008)28[160:CAOETS]2.0.CO;2. ISSN0272-4634.
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