''Nannaroter'' 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 ...

of Recumbirostran tetrapod within the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Ostodolepidae Ostodolepidae, also spelled Ostodolepididae, is an extinct family of Early Permian microsaurs. They are unique among microsaurs in that they were large, reaching lengths of up to , terrestrial, and presumably fossorial. Ostodolepid remains have b ...

History of study

''Nannaroter'' was named in 2009 by Canadian paleontologists Jason Anderson, Diane Scott, and Robert Reisz. It was known from only 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 ...

specimen, which was found at the

Richards Spur Richards Spur is a Permian fossil locality located at the Dolese Brothers Limestone Quarry north of Lawton, Oklahoma. The locality preserves clay and mudstone fissure fills of a karst system eroded out of Ordovician limestone and dolomite (rock), d ...

locality in Oklahoma. The holotype, a well preserved skull, was found in early Permian-aged fissure fill deposits in

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

. The specific name is given for Mark McKinzie, who found and donated the specimen to the

Sam Noble Oklahoma Museum of Natural History Sam, SAM or variants may refer to: Places * Sam, Benin * Sam, Boulkiemdé, Burkina Faso * Sam, Bourzanga, Burkina Faso * Sam, Kongoussi, Burkina Faso * Sam, Iran * Sam, Teton County, Idaho, United States, a populated place People and fictio ...

. In 2021 a second specimen was referred, ROMVP 86541, a skull with right lower jaw.

Anatomy

''Nannaroter'' is the smallest known ostodolepid and is diagnosed by: (1) the high subtemporal recess that separates the postorbital from the squamosal; (2) four premaxillary tooth positions; (3) 12 maxillary tooth positions; circumorbital walls formed by medial laminae of the prefrontal, lacrimal, and jugal; (5) a ventral flange of the frontal meeting the sphenethmoid; (7) an anterolaterally bulbous sphenethmoid; and (8) a massive epipterygoid. 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, as indicated by the markedly interdigitated sutures.

Ecology

The high degree of ossification in the skull of ''Nannaroter'' is seen as an adaptation to a fossorial, or burrowing, lifestyle. More specifically, the animal would likely have used its recumbent snout to push forward into the substrate, facilitated by increased epaxial musculature that inserted into the broad, sloping occiput, as in amphisbaenians. As ''Nannaroter'' was known from only one specimen, it has been suggested that it was either a naturally rare component of the assemblage or that its inferred burrowing ecology did not lend itself well to preservation in the fissure fill system.

Relationships

Below is the placement of ''Nannaroter'' in the analysis of Huttenlocker et al. (2013):

References

{{Taxonbar, from=Q6963817 Cisuralian amphibians of North America Ostodolepids Fossil taxa described in 2009