Hapsidopareiontidae is an extinct family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of tuditanomorph

Tuditanomorpha

Tuditanomorpha is a suborder of microsaur lepospondyls. Tuditanomorphs lived from the Late Carboniferous to the Early Permian and are known from North America and Europe. Tuditanomorphs have a similar pattern of bones in the skull roof. Tuditanomorphs display considerable variability, especially in...

 microsaurs. Hapsidopareiontids are known from the Early Permian of the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and possibly 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...

 and the Czech Republic

Czech Republic

The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....

.

Hapsidopareiontids are characterized by a large temporal embayment near the cheek region in which the quadratojugal

Quadratojugal

The quadratojugal is a small jaw bone that is present in most amphibians, reptiles, and birds, but has been lost in mammals. It is connected to the jugal as well as other bones, though these may vary with species....

 is greatly reduced or absent. Members of Ostodolepidae

Ostodolepidae

Ostodolepidae is an extinct family of tuditanomorph microsaurs. They are unique among microsaurs in that they were large, reaching lengths of up to , terrestrial, and presumably fossorial. Ostodolepid remains have been found from Early Permian beds in Texas and Oklahoma.Ostodolepids have elongated...

, another microsaur family, also possess temporal embayments, but they not as extensive as those of hapsidopareiontids, which extend into the skull roof

Skull roof

The skull roof , or the roofing bones of the skull are a set of bones covering the brain, eyes and nostrils in bony fishes and all land living vertebrates. The bones are derived from dermal bone, hence the alternative name dermatocranium...

. In hapsidopareiontids, the embayment may have provided space for an enlarged jaw adductor musculature, although certain characteristics of the skull do not support this idea. Hapsidopareion

Hapsidopareion

Hapsidopareion is an extinct genus of microsaur within the family Hapsidopareiontidae.-See also:* Prehistoric amphibian* List of prehistoric amphibians...

and Llistrofus

Llistrofus

Llistrofus is an extinct genus of microsaur within the family Hapsidopareiontidae.-See also:* Prehistoric amphibian* List of prehistoric amphibians...

both possess this embayment, but in 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...

, the temporal region is complete. The lack of a temporal embayment may exclude Saxonerpeton from Hapsidopareiontidae; Bolt and Rieppel (2009) considered Hapsidopareiontidae to include only Hapsidopareion and Llistrofus because of this.