| Batropetes Temporal range:Early Permian | |
|---|---|
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| Restoration ofBatropetes fritschi | |
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Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Family: | †Brachystelechidae |
| Genus: | †Batropetes Carroll and Gaskill, 1971 |
| Species | |
†B. appelensisGlienke, 2015 | |
| Synonyms | |
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Batropetes is an extinctgenus ofbrachystelechidrecumbirostran "microsaur".Batropetes lived during theSakmarian stage[a] of theEarly Permian. Fossils attributable to thetype speciesB. fritschi have been collected from the town ofFreital inSaxony,Germany, near the city ofDresden. Additional material has been found from theSaar-Nahe Basin in southwestern Germany and has been assigned to three additional species:B. niederkirchensis,B. palatinus, andB. appelensis.
![[icon]](/mt/?noimg=&dark=on&url=https%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aWiki_letter_w_cropped.svg) | This sectionneeds expansion with: The differences between the four species are not mentioned. You can help byadding to it.(October 2015) |
Batropetes is small and short-bodied for a microsaur. Its average total body length was about 8 centimetres (3.1 in).[1] Theorbits are large and the skull is short.Batropetes possesses scales on its underside that are similar to those of reptiles.[2]
Batropetes is distinguished fromCarrolla, another brachystelechid microsaur, by the presence of three cusps on the premaxillary and anterior dentary teeth. InCarrolla, there are only two cusps. Additional diagnostic features seen inBatropetes include a supraoccipital bone that is not fused to theotic capsule, the presence of aretroarticular process (a projection at the back of the lower jaw), and two proximal bones in thetarsus.[2]
The first known material now attributed to the genusBatropetes was originally referred to the genusHyloplesion in 1882.[3] Several specimens from Freital were described under the nameHyloplesion Fritschi as small non-labyrinthodonts. Three years later, the specimens originally referred to asHyloplesion Fritschi were reassigned byCarl Hermann Credner to the genusHylonomus under the nameHylonomus fritschia.[b][4] Newly discovered specimens of other forms from the same locality led Credner to believe that two taxa existed. He named one, an amphibian,Hylonomus geinitzi, and the other, a reptile,Petrobates truncatus.[5]
Later preparation of the material examined by Credner through a technique of removing the soft bone from the surrounding matrix mechanically and casting the cavities in liquid latex has revealed more anatomical detail suggesting that three taxa were present in Freital, not two. A specimen previously referred toPetrobates truncatus was first considered byRobert L. Carroll andPamela Gaskill in 1978 to be a microsaur rather than a reptile.[6] It was considered distinct fromPetrobates, then considered acaptorhinomorph, based only on the structure of theatlas.
Of the three species represented in Frietal,Hylonomus geinitzi, as described by Credner, has since been reassigned to the microsaur genusSaxonerpeton, andPetrobates truncatus was designated asBatropetes truncatus by Carroll and Gaskill in 1971.[6][7] Carroll and Gaskill still referred toB. truncatus as a captorhinomorph reptile.
Carroll and Gaskill described a new microsaur in 1978 from Frietal, which they calledBrachystelechus fritschi.[6] It was noted that the skull ofBrachystelechus bore a striking resemblance to that ofBatropetes, which was considered to be unrelated. It differed fromBatropetes in that it possessed an internarial bone which was not seen in known specimens ofBatropetes.
A newly discovered specimen of microsaur from the Saar-Nahe district in southwestern Germany has confirmed thatBrachystelechus andBatropetes represent the same species.[2] The characters that previously distinguished the two genera from one another are all found in one specimen, known as SMNS 55884, housed in theStaatliches Museum für Naturkunde Stuttgart. This a complete specimen preserved in ventral view and consisting of a part and counterpart. The skull roof was examined by excavating the matrix from the top of the block and exposing more anatomical features. Theoccipital condyle in SMNS 55884, not noticeable in the specimen ofBrachystelechus, clearly indicates that it is a microsaur rather than a captorhinomorph reptile. An interfrontal bone is seen in material once referred toBrachystelechus but not in any material known from specimens previously attributed toBatropetes. This may be a result of poor preservation, or perhaps intraspecific variation. Theparietals of the specimen are wide and the skull is short, both of which are features that associate it with the North American generaCarrolla andQuasicaecilia.[8][9] On the basis of these and other similarities, Carroll, who described the new material in 1991, constructed a new microbrachomorph family called the Brachystelechidae to includeBatropetes,Carrolla, andQuasicaecilia.[2]
A 2013 study ofBatropetes erected a new species,Batropetes niederkirchensis, for specimen SMNS 55884. SMNS 55884 was noted to differ from thetype specimen ofB. fritschi in the number of presacral vertebrae, the width between the eye sockets, the shape of theprefrontal,postorbital, andscapulocoracoid bones, and the position of theobturator foramen in the hips.[10] Two additional species,B. appelensis andB. palatinus, were named in 2015 on the basis of new material found from the Saar-Nahe Basin.[1]
During the 2010s,recumbirostran microsaurs, includingbrachystelechids, were increasingly considered to be early divergingsauropsids, rather thanreptiliomorphs.[11]
