''Feeserpeton'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

parareptile Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids (reptiles), typically considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near th ...

from the Early Permian of Richard's Spur, Oklahoma. It is known from a single species, ''Feeserpeton oklahomensis'', which was named in 2012 on the basis of a nearly complete skull. ''Feeserpeton'' is a member of the clade Lanthanosuchoidea and is one of the earliest parareptiles.

Description

The only known skull of ''Feeserpeton'' is small, but well-fused bones, deep pitting, and worn teeth indicate that the individual was close to maturity when it died. Large eye sockets may indicate that ''Feeserpeton'' was nocturnal. The skull is nearly complete, missing parts of the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

(a bone at the tip of the snout) and the

jugal The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anatomy ...

(a bone making up the "cheek" region). A combination of features distinguish ''Feeserpeton'' from other related parareptiles, including a triangular skull, large caniniform teeth in the upper and lower jaws, and

postorbital bone The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some v ...

s behind the eye sockets that are much larger than the nearby

squamosal bone The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral c ...

s. Part of the

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly separ ...

is exposed on the right side of the skull, revealing many worn palatal teeth. The teeth in the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

or lower jaw are hidden beneath the bones of the upper jaw, but CT scanning has revealed that there is a single tooth row on each side with mostly small teeth. Two teeth are much larger than the rest, similar in size to the enlarged caniniforms of the upper jaw. The braincase is preserved at the back of the skull and includes the

stapes The ''stapes'' or stirrup is a bone in the middle ear of humans and other animals which is involved in the conduction of sound vibrations to the inner ear. This bone is connected to the oval window by its annular ligament, which allows the foo ...

, a bone rarely preserved in parareptile fossils. ''Feeserpeton'' has a large opisthotic bone in its braincase, similar in size to that of another Early Permian parareptile called '' Acleistorhinus''.

Discovery

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

skull of ''Feeserpeton'', cataloged as OMNH 73541, was found in the Dolese Brothers Limestone Quarry near the town of Richard's Spur, Oklahoma. Several other parareptiles have also been found from Richard's Spur, including ''

Bolosaurus ''Bolosaurus'' (from Ancient Greek ''bolos'', "lump" + ''sauros'': lizard]) is an extinct genus of bolosaurid ankyramorph parareptile from the Cisuralian epoch (middle Sakmarian to early Kungurian stages) of North Asia and North America (Red ...

'', '' Colobomycter'', '' Delorhynchus'', '' Microleter'', and an

acleistorhinid Acleistorhinidae is an extinct family of Late Carboniferous and Early Permian-aged (Moscovian to Kungurian stage) parareptiles. Acleistorhinids are most diverse from the Richards Spur locality of the Early Permian of Oklahoma. Richards Spur aclei ...

. OMNH 73541 was preserved in a

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

-rich nodule of calcite which was removed during preparation. CT scans of the skull revealed many internal details. The specimen was described as a new genus and species in 2012. The genus name ''Feeserpeton'' honors Mike Feese, a manager of the Dolese Brothers quarry who was also a fossil collector, and the species name ''oklahomensis'' refers to Oklahoma, the state in which it was found.

Phylogeny

''Feeserpeton'' was included in a

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis when it was first named in 2012. It nested within the clade Lanthanosuchoidea, a poorly known group that includes the parareptiles ''Acleistorhinus'' and '' Lanthanosuchus''. ''Feeserpeton'' was found to be a basal member of this group, the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

of a clade including ''Acleistorhinus'' and ''Lanthanosuchus''. Features that place ''Feeserpeton'' within Lanthanosuchoidea include a ridge on the

frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, pa ...

above the eye socket, a plate-like

supraoccipital The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...

bone with a sagittal crest on the braincase, and a notch midway along the margin of the back of the skull. ''Feeserpeton'' is the oldest member of the clade. Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

from the analysis showing the position of ''Feeserpeton'':

References

{{Taxonbar, from=Q5441460 Permian vertebrates of North America Procolophonomorphs Prehistoric reptile genera