Batropetes
Encyclopedia
Batropetes is an extinct genus
of brachystelechid
microbrachomorph. Although it was first classified as a reptile
, Batropetes is now known to be a microsaur amphibian
. Fossils have been collected from the town of Freital
in Saxony
, Germany
, near the city of Dresden
. Additional material has been found from the Saar-Nahe Basin in southwestern Germany. The genus is known to have lived during the Sakmarian
stage of the Early Permian (in European lithostratigraphy
this is known as the Rotliegend
).
are large and the skull is short. Batropetes possesses scales on its underside that are similar to those of reptiles.
Batropetes is distinguished from Carrolla
, another brachystelechid microsaur, by the presence of three cusps on the premaxillary and anterior dentary teeth. In Carrolla, there are only two cusps. Additional diagnostic features seen in Batropetes include a supraoccipital bone that is not fused to the otic capsule, the presence of a retroarticular process (a projection at the back of the lower jaw), and two proximal bones in the tarsus
.
in 1882. Several specimens from Freital were described under the name Hyloplesion Fritschi as small non-labyrinthodonts
. Three years later, the specimens originally referred to as Hyloplesion Fritschi were reassigned by Carl Hermann Credner
to the genus Hylonomus
under the name Hylonomus fritschia. 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.
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 that suggested that three taxa were present in Freital, not two. A specimen previously referred to Petrobates truncatus was first considered by Robert L. Carroll
and Pamela Gaskill in 1978 to be a microsaur rather than a reptile. It was considered distinct from Petrobates, then considered a captorhinomorph
, based only on the structure of the atlas
.
Of the three species represented in Frietal, Hylonomus geinitzi, as described by Credner, has since been reassigned to the microsaur genus Saxonerpeton
, and Petrobates truncatus was designated as Batropetes truncatus by Carroll and Gaskill in 1971. Carroll and Gaskill still referred to B. truncatus as a captorhinomorph reptile.
Carroll and Gaskill described a new microsaur in 1978 from Frietal which they called Brachystelechus fritschi. It was noted that the skull of Brachystelechus bore a striking resemblance to that of Batropetes, which was considered to be unrelated. It differed from Batropetes in that it possessed an internarial bone which was not seen in known specimens of Batropetes.
A newly discovered specimen of microsaur from the Saar-Nahe district in southwestern Germany has confirmed that Brachystelechus and Batropetes represent the same species. The characters that previously distinguished the two genera from one another are all found in one specimen, known as SMNS 55884, housed in the Staatliches Museum für Naturkunde Stuttgart. This a complete specimen preserved in ventral view and consisting of a part and counter part. The skull roof was able to be examined by excavating the matrix from the top of the block. Therefore, more anatomical features could be observed in the specimen. The occipital condyle
in SMNS 55884 clearly indicates that it is a microsaur rather than a captorhinomorph reptile. The occipital condyle was not noticeable in the specimen of Brachystelechus. An interfrontal bone is seen in material once referred to Brachystelechus but not in any material known from specimens previously attributed to Batropetes. This may be a result of poor preservation, or perhaps intraspecific variation. The parietals
of the specimen are wide and the skull is short, both of which are features that associate it with the genera Carrolla
and Quasicaecilia, both of which have been found from North America
. 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 include Batropetes, Carrolla, and Quasicaecilia.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of brachystelechid
Brachystelechidae
Brachystelechidae is an extinct family of Early Permian microsaurs. The family was first named by Robert L. Carroll and Pamela Gaskill in 1978, with the only member being Brachystelechus fritschi. Brachystelechus fritschi has since been reassigned to the genus Batropetes...
microbrachomorph. Although it was first classified as a reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
, Batropetes is now known to be a microsaur amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
. Fossils have been collected from the town of Freital
Freital
Freital is the biggest town in the Sächsische Schweiz-Osterzgebirge district, in the Free State of Saxony, Germany. It is situated on the small river Weißeritz, 8 km southwest of Dresden.- Geography :...
in Saxony
Saxony
The Free State of Saxony is a landlocked state of Germany, contingent with Brandenburg, Saxony Anhalt, Thuringia, Bavaria, the Czech Republic and Poland. It is the tenth-largest German state in area, with of Germany's sixteen states....
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, near the city of Dresden
Dresden
Dresden is the capital city of the Free State of Saxony in Germany. It is situated in a valley on the River Elbe, near the Czech border. The Dresden conurbation is part of the Saxon Triangle metropolitan area....
. Additional material has been found from the Saar-Nahe Basin in southwestern Germany. The genus is known to have lived during the Sakmarian
Sakmarian
In the geologic timescale, the Sakmarian is an age or stage of the Permian. It is a subdivision of the Cisuralian epoch or series. The Sakmarian lasted between 294.6 ± 0.8 and 284.4 ± 0.7 million years ago...
stage of the Early Permian (in European lithostratigraphy
Lithostratigraphy
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology...
this is known as the Rotliegend
Rotliegend
The Rotliegend or Rotliegendes is a lithostratigraphic unit of Cisuralian age that is found in the subsurface of large areas in western and central Europe. The Rotliegend mainly consists of sandstone layers...
).
Description
Batropetes is small and short-bodied for a microsaur. The orbitsOrbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
are large and the skull is short. Batropetes possesses scales on its underside that are similar to those of reptiles.
Batropetes is distinguished from Carrolla
Carrolla
Carrolla is an extinct genus of prehistoric amphibian.-See also:* Prehistoric amphibian* List of prehistoric amphibians...
, another brachystelechid microsaur, by the presence of three cusps on the premaxillary and anterior dentary teeth. In Carrolla, there are only two cusps. Additional diagnostic features seen in Batropetes include a supraoccipital bone that is not fused to the otic capsule, the presence of a retroarticular process (a projection at the back of the lower jaw), and two proximal bones in the tarsus
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
.
Classification
The first known material now attributed to the genus Batropetes was originally referred to the genus HyloplesionHyloplesion
Hyloplesion is an extinct genus of microbrachomorph microsaur. It is the type and only genus within the family Hyloplesiontidae. Fossils have been found from the Czech Republic near the towns of Plzeň, Nýřany, and Třemošná, and date back to the Middle Pennsylvanian. The type species is H....
in 1882. Several specimens from Freital were described under the name Hyloplesion Fritschi as small non-labyrinthodonts
Labyrinthodontia
Labyrinthodontia is an older term for any member of the extinct subclass of amphibians, which constituted some of the dominant animals of Late Paleozoic and Early Mesozoic times . The group is ancestral to all extant landliving vertebrates, and as such constitutes an evolutionary grade rather...
. Three years later, the specimens originally referred to as Hyloplesion Fritschi were reassigned by Carl Hermann Credner
Carl Hermann Credner
Carl Hermann Credner was a German earth scientist and the son of Carl Friedrich Heinrich Credner.Credner was born at Gotha, educated at Breslau and Göttingen, and took the degree of Ph.D. at Breslau in 1864...
to the genus Hylonomus
Hylonomus
Hylonomus was a very early reptile. It lived 312 million years ago during the Late Carboniferous period.It is the earliest unquestionable reptile ....
under the name Hylonomus fritschia. 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.
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 that suggested that three taxa were present in Freital, not two. A specimen previously referred to Petrobates truncatus was first considered by Robert L. Carroll
Robert L. Carroll
Robert Lynn Carroll is a vertebrate paleontologist who specialises in Paleozoic and Mesozoic amphibians and reptiles.Carroll was an only child and grew up on a farm near Lansing, Michigan...
and Pamela Gaskill in 1978 to be a microsaur rather than a reptile. It was considered distinct from Petrobates, then considered a captorhinomorph
Captorhinomorpha
Captorhinomorpha is a suborder of prehistoric reptiles which appeared in the Carboniferous period and became extinct after the Early Permian period....
, based only on the structure of the atlas
Atlas (anatomy)
In anatomy, the atlas is the most superior cervical vertebra of the spine.It is named for the Atlas of Greek mythology, because it supports the globe of the head....
.
Of the three species represented in Frietal, Hylonomus geinitzi, as described by Credner, has since been reassigned to the microsaur genus Saxonerpeton
Saxonerpeton
Saxonerpeton is an extinct genus of microsaur of the family Hapsidopareiontidae. Fossils have been found from Early Permian strata near Dresden, Germany.-External links:* in the Paleobiology Database...
, and Petrobates truncatus was designated as Batropetes truncatus by Carroll and Gaskill in 1971. Carroll and Gaskill still referred to B. truncatus as a captorhinomorph reptile.
Carroll and Gaskill described a new microsaur in 1978 from Frietal which they called Brachystelechus fritschi. It was noted that the skull of Brachystelechus bore a striking resemblance to that of Batropetes, which was considered to be unrelated. It differed from Batropetes in that it possessed an internarial bone which was not seen in known specimens of Batropetes.
A newly discovered specimen of microsaur from the Saar-Nahe district in southwestern Germany has confirmed that Brachystelechus and Batropetes represent the same species. The characters that previously distinguished the two genera from one another are all found in one specimen, known as SMNS 55884, housed in the Staatliches Museum für Naturkunde Stuttgart. This a complete specimen preserved in ventral view and consisting of a part and counter part. The skull roof was able to be examined by excavating the matrix from the top of the block. Therefore, more anatomical features could be observed in the specimen. The occipital condyle
Occipital condyle
The occipital condyles are undersurface facets of the occipital bone in vertebrates, which function in articulation with the superior facets of the atlas vertebra....
in SMNS 55884 clearly indicates that it is a microsaur rather than a captorhinomorph reptile. The occipital condyle was not noticeable in the specimen of Brachystelechus. An interfrontal bone is seen in material once referred to Brachystelechus but not in any material known from specimens previously attributed to Batropetes. This may be a result of poor preservation, or perhaps intraspecific variation. The parietals
Parietal bone
The parietal bones are bones in the human skull which, when joined together, form the sides and roof of the cranium. Each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin pariet-, wall....
of the specimen are wide and the skull is short, both of which are features that associate it with the genera Carrolla
Carrolla
Carrolla is an extinct genus of prehistoric amphibian.-See also:* Prehistoric amphibian* List of prehistoric amphibians...
and Quasicaecilia, both of which have been found from North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. 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 include Batropetes, Carrolla, and Quasicaecilia.
See also
- Prehistoric amphibian
- List of prehistoric amphibians
External links
- Batropetes in the Paleobiology DatabasePaleobiology Database' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...