| Abyssomedon Temporal range: 289–Early Permian Ma | |
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| An artist's illustration of the holotype fossil | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Order: | †Procolophonomorpha |
| Family: | †Nyctiphruretidae |
| Genus: | †Abyssomedon MacDougall & Reisz, 2014 |
| Species: | †A. williamsi |
| Binomial name | |
| Abyssomedon williamsi MacDougall & Reisz, 2014 | |
Abyssomedon (meaning "Guardian of the Abyss") is an extinct genus of a nyctiphruretid parareptile known from Early Permian (Artinskian age) fissure fills at Richards Spur in Comanche County, Oklahoma, south-central United States. It contains a single species, A. williamsi, which represents the oldest known nyctiphrureptid species and the first to be discovered in North America.
Discovery[]
Abyssomedon is known solely from the holotype BMRP 2008 33a, a partial skeleton housed at the Burpee Museum of Natural History at Rockford, Illinois. The specimen consists of a semi-articulated partial skull and disarticulated but associated postcranial remains. BMRP 2008 33a was discovered in 2008 in a claystone and conglomerate nodule found at Oklahoma Museum of Natural History (OMNH) Locality V51. This site, known as Richards Spur, is located just west of U.S. Highways 62 & 281, 10.5 miles south of Apache and 6 miles north of Fort Sill, of Comanche County, Oklahoma. The fossils of Richards Spur are found in Early Permian fissure fills in Ordovician limestone.
Abyssomedon was first described and named by Mark J. MacDougall and Robert R. Reisz in 2014 and the type species is Abyssomedon williamsi. The generic name is derived from Greek Abyssos, meaning "deep pit", and -medon, meaning "guardian", in reference to the cave system at Richards Spur. The specific name williamsi honor the collector of the holotype Mr. Scott Williams, a paleontologist at the Burpee Museum.