Romeriscus
{{Short description|Uncertain genus of prehistoric tetrapod}}
{{Speciesbox
| genus = Romeriscus
| parent_authority = Baird & Carroll, 1968
| species = periallus
| authority = Baird & Carroll, 1968
}}
Romeriscus is a dubious genus of tetrapod, currently classified as in the family Limnoscelidae,{{GBIF|title=Romeriscus Baird & Carroll, 1968|id=4823368}} found in the Lower Pennsylvanian Port Hood formation in Nova Scotia.{{Cite journal |last1=Baird |first1=D. |last2=Carroll |first2=R. L. |date=1967-07-07 |title=Romeriscus, the oldest known reptile |url=https://pubmed.ncbi.nlm.nih.gov/6026664/ |journal=Science |volume=157 |issue=3784 |pages=56–59 |doi=10.1126/science.157.3784.56 |issn=0036-8075 |pmid=6026664|bibcode=1967Sci...157...56B }}
Romeriscus is known by one species, Romeriscus periallus, from a single holotype, YPM-PU16 482. The holotype specimen has both cranial and post-cranial remains and consists of a badly crushed skull and 25 pre-sacral vertebrae.
It was originally described in 1967 by Baird & Carroll and hypothesized be a limnoscelid due to its skull structure. In 1992, however, this claim was refuted by Laurin & Reisz, who state that the poor preservation of the skull makes such a claim impossible, and that due to its poor condition, the frontal and postfrontal portions of the skull cannot be properly identified as a limnoscelid.{{Cite journal |last1=Laurin |first1=Michel |last2=Reisz |first2=Robert R. |date=1992 |title=A Reassessment of the Pennsylvanian Tetrapod Romeriscus |url=https://www.jstor.org/stable/4523476 |journal=Journal of Vertebrate Paleontology |volume=12 |issue=4 |pages=524–527 |doi=10.1080/02724634.1992.10011478 |jstor=4523476 |bibcode=1992JVPal..12..524L |issn=0272-4634|url-access=subscription }} Laurin & Reisz came to the conclusion that while Romeriscus is a distinct genus, it cannot conclusively be classified as amniota, or limnoscelidae, instead classifying it as tetrapoda incertae sedis, and nomen dubium, as its status as a Romeriid is unclear.{{Cite book |last1=J Clark |url=http://archive.org/details/biostor-690 |title=Romeriid reptiles from the Lower Permian |last2=R L Carroll |date=1973 |language=English}}