Omosaurus is a nomen dubium genus of extinct crurotarsi reptile, possibly a phytosaur, from the Late Triassic (Carnian) of North Carolina.
Discovery and naming
In the middle of the nineteenth century,
geologist Professor
Ebenezer Emmons discovered several reptilian teeth in the
colliery of the
Chatham company in
North Carolina.
[E. Emmons. (1857). American Geology, Containing a Statement of the Principles of the Science with Full Illustrations of the Characteristic American Fossils. With an Atlas and a Geological Map of the United States Part IV:x-152] In 1856, the fossils in his collection were described by
paleontologist Joseph Leidy. Leidy combined the teeth with some vertebrae and ribs; adding to them an
osteoderm or
scute found in the same strata by Professor
Michael Tuomey, he named the whole
Omosaurus perplexus.
[J. Leidy, (1856), "Notice of remains of extinct vertebrated animals discovered by Professor E. Emmons", Proceedings of the Academy of Natural Sciences of Philadelphia 8: 255-257] Leidy provided no
etymology; the specific name suggests he was intrigued by the "intricate" find. The generic name might be derived from the Greek ὠμός,
omos, "rough", perhaps in reference to the rough surface of the scute or to the "savage" nature of a carnivorous reptile. Today, all
are lost.
Description
The teeth were described as being rather straight, slightly curved inwards, conical and pointed with a length of up to one inch. They had two edges at the inside and a D-shaped cross-section with the convex part positioned at the outer side. The surface of the teeth was smooth with little wrinkles, running vertically at the inside and horizontally at the outside. The vertebrae were
amphicoelous and constricted at the waist, with a length of about three centimetres and somewhat taller than wide in cross-section. The scute was ornamented with a fan-shaped pattern of splitting ridges.
Phylogeny
Leidy himself believed
Omosaurus to be a marine reptile, probably a
plesiosaur, suspecting the remains were referable to some already named genus.
In 1902, Frederick Augustus Lucas recognised the fossils as "crocodilian" in nature and placed
Omosaurus in the
Crocodilia. At the same time he affirmed the priority over
Omosaurus (
Richard Owen 1875), which
stegosaur was by him renamed to
Dacentrurus.
[F.A. Lucas, (1902), "Paleontological notes. The generic name Omosaurus: A new generic name for Hoplitosaurus", Science, new series 16(402): 435] Today,
Omosaurus is commonly listed as a
nomen dubium, a possible member of the
Phytosauria.
