Nannaroter is an extinct genus

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 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...

 microsaur within the 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...

 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...

. It is known from only the holotype

Holotype

A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 specimen, which was found in the Dolese Brothers Limestone Quarry in Oklahoma

Oklahoma

Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...

. The holotype, a well preserved skull, was found in Early Permian-aged fissure fill deposits in Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

.

Nannaroter is the smallest known ostodolepid. Like other ostodolepids, it has a wedge-shaped skull, a pointed snout, and a temporal emargination. The skull is highly ossified in order to resist anteroposteriorly directed forces. There is a large triangular pterygoid-epipterygoid complex that reinforces the posterolateral wall of the braincase. The walls of the orbits

Orbit (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...

, or eye sockets, are thickened. The high degree of ossification in the skull of Nannaroter is seen as an adaptation to a fossorial

Fossorial

A fossorial organism is one that is adapted to digging and life underground such as the badger, the naked mole rat, and the mole salamanders Ambystomatidae...

, or burrowing, lifestyle.