Coelostegus

{{Short description|Extinct genus of reptiles}}

{{Speciesbox

| fossil_range = Late Carboniferous, {{fossil_range|307.1|305}}

| image = Coelostegus prothales skull reconstruction.png

| image_caption = Skull reconstruction

| display_parents = 2

| parent_authority = Carroll & Baird, 1972

| taxon = Coelostegus prothales

| authority = Carroll & Baird, 1972

}}

Coelostegus is an extinct genus of Late Carboniferous (late Westphalian stage) basal reptile known from Plzeň of Czech Republic. It is known from the holotype ČGH 3027, a partial skeleton of an immature individual. It was collected in the Nýřany site from the Nýřany Member of the Kladno Formation. It was first named by Robert L. Carroll and Donald Baird in 1972 and the type species is Coelostegus prothales.{{cite journal |author=Robert L. Carroll |author2=Donald Baird |name-list-style=amp |year=1972 |title=Carboniferous Stem-Reptiles of the Family Romeriidae |journal=Bulletin of the Museum of Comparative Zoology |volume=143 |issue=5 |pages=321–363 }} The most recent phylogenic study of primitive reptile relationships found Coelostegus to be the basalmost known eureptile.{{cite journal |last=Müller |first=J. |author2=Reisz, R. R. |year=2006 |title=The phylogeny of early eureptiles: comparing parsimony and Bayesian approaches in the investigation of a basal fossil clade |journal=Systematic Biology |pmid=16861212 |volume=55 |issue=3 |pages=503–511 |doi=10.1080/10635150600755396|doi-access=free}}