|
Stratigraphic chart of the lower Permian (partial) Content updated October 16, 2005
|
REPTILE X OF BOLT Microsaur? Parareptile? In 1980 premaxillary, maxillary and dentary fossil fragments of Richards Spur were described by Bolt as belonging to two distinct, though similar, taxa, he considered them probable reptiles or microsaurs, these specimens were characterized by the presence of weakly bicuspid, not labirinthodont teeth. These teeth are fluted and labiolingually recurved , the premaxilla has a very slender dorsal process, the maxilla has a large maxillary foramen. The smaller one were named Reptile X. In 1996 DeBraga and Reisz described the presence of a large maxillary foramen in Acleistorhinus as diagnostic character of all the parareptiles, suggesting the possibility that also the Bolt reptiles could be parareptiles. In 2003 Anderson and Reisz described a new dentary, belonging to the larger of the Bolt reptiles, articulated with two coronoids covered by teeth similar to the ones of Cardiocephalus, so they concluded that the larger of the "reptiles" of Bolt was a microsaur closely related with Cardiocephalus and named it Bolterpeton Carrolli, they raised also the possibility that also the smaller Reptile X could be a microsaur, perhaps an ontogenetic variation of the larger one. But Bulanov (2002) suggested in his article that the Fort Sill material described by Bolt belong to a nyctiphruretid, infact the shape of the maxilla and of the teeth is almost identical. |