''Ambedus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of possible

diadectid Diadectidae is an extinct family of early tetrapods that lived in what is now North America and Europe during the Late Carboniferous and Early Permian in Asia during the Late Permian. They were the first herbivorous tetrapods, and also the first ...

reptiliomorph Reptiliomorpha (meaning reptile-shaped; in PhyloCode known as ''Pan-Amniota'') is a clade containing the amniotes and those tetrapods that share a more recent common ancestor with amniotes than with living amphibians ( lissamphibians). It was de ...

. Fossils have been found from the

Early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), 01'' (Richard Müller album), 2001 * 01 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...

Dunkard Group of

Monroe County Monroe County may refer to seventeen counties in the United States, all named for James Monroe: * Monroe County, Alabama *Monroe County, Arkansas * Monroe County, Florida * Monroe County, Georgia *Monroe County, Illinois *Monroe County, Indian ...

Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...

. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

''A. pusillus'' was named in 2004. The genus name comes from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word ''ambedo'' meaning "to nibble", in reference to its herbivorous diet. The specific name ''pusillus'' means "tiny" in Latin.

Description

''Ambedus'' is a small tetrapod, possible Diadectid, known only from

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

e and

dentary 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 tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

bones. It is usually considered the most primitive diadectid because unlike other forms it had a small, shallow lower jaw and many simple, conical teeth. It was also smaller than the later, rather bulky diadectids. Later diadectids have deep jaws with few teeth and forward-projecting incisiforms at the tips of the jaws for consuming plant material, and a corresponding greater girth. David Berman's 2013 paper argued against the inclusion of Ambedus in Diadectidae, for several reasons. He stated in his paper that it's assignment to Diadectidae is based only on several isolated maxillae and dentaries that had cheek teeth that only exhibited a resemblance in their molar-like morphology to those in Diadectids. There are also a number of other characteristics that distuinguish Ambedus from all other Diadectids, such as a shallow rather than deep deep dentary, and relatively high maxillary and dentary tooth counts, among other characteristics that distuinguish them from Diadectids. Furthermore, the appearance of Ambedus pusillus so late in the fossil record, after all known Diadectomorphs have died out,also casts a doubt on the fact that it is supposed to represent the basalmost member of the Diadectid lineage. In contrast, the first Diadectids from the Upper Pennsylvanian were way more developed and had the characteristic dentary and maxillary features of the Diadectid lineage. This implicates that there should be a ghost lineage that goes back all the way back to the Middle Pennsylvanian, which is highly unlikely.

Paleobiology

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 several ...

specimen of ''Ambedus'' was found from an outcrop of the Early Permian the

Greene Formation The Greene Formation is a geologic formation in West Virginia, Ohio, Maryland, Virginia and Pennsylvania. It preserves fossils dating back to the Permian period Period may refer to: Common uses * Era, a length or span of time * Full stop (o ...

on Clark Hill in Monroe County, Ohio. It was found alongside fossils of the

lungfish Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, i ...

Sagenodus ''Sagenodus'' is an extinct genus of prehistoric lungfish. It is a lungfish from the Permo-Carboniferous period found in Europe and North America. See also * Sarcopterygii * List of sarcopterygians * List of prehistoric bony fish References

'', the

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order (biology), order of small to giant tetrapods—often considered Labyrinthodontia, primitive amphi ...

amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...

Trimerorhachis ''Trimerorhachis'' is an extinct genus of dvinosaurian temnospondyl within the family Trimerorhachidae. It is known from the Early Permian of the southwestern United States, with most fossil specimens having been found in the Texas Red Beds. Th ...

'', an

embolomere Embolomeri is an Order (biology), order of Tetrapod, tetrapods or Stem-group, stem-tetrapods, possibly members of Reptiliomorpha. Embolomeres first evolution, evolved in the Early Carboniferous (Mississippian age, Mississippian) Period and were th ...

reptiliomorph, and the

synapsid Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...

Ctenospondylus ''Ctenospondylus'' ("comb vertebra") is an extinct genus of sphenacodontid synapsid Species were about three meters (ten feet) long. The genus is known only from the 'Seymouran' Land Vertebrate Faunachron, which is equivalent to the upper part ...

''. These animals likely lived alongside a freshwater lake or pond.

References

Diadectids Artinskian genera Kungurian genera Cisuralian tetrapods of North America Permian Ohio Paleontology in Ohio Fossil taxa described in 2004 Taxa named by Robert R. Reisz {{Permian-animal-stub