Nanictidopidae is an extinct

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

therocephalian Therocephalia is an extinct suborder of eutheriodont therapsids (mammals and their close relatives) from the Permian and Triassic. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their te ...

therapsid Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more ...

s from the

Late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

. Two genera are currently included in the family, '' Nanictidops'' from

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

and '' Purlovia'' from

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. Nanictidopids have short skulls and were probably herbivorous.

Description

In comparison to other therocephalians, nanictidopids are relatively large, with skulls ranging from in length. Nanictidopids are characterized by their shortened skulls that appear triangular when viewed from above. The temporal region of the skull is very wide. Their skulls are similar to those of hofmeyriids, and the superfamily Nanictidopoidea has been established to unite these two groups. Nanictidopids have enlarged

canine teeth In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened howeve ...

in their upper and lower jaws, while the teeth behind them are very small. Small bumps and ridges cover parts of the upper and lower jaws. The parietal region at the back of the skull forms a

sagittal crest A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exceptiona ...

. The

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 ve ...

s that make up the back of the eye sockets are very thin, and sometimes do not enclose the entire socket. Unlike more advanced therocephalians, nanictidopids lack a

secondary palate The secondary palate is an anatomical structure that divides the nasal cavity from the oral cavity in many vertebrates. In human embryology, it refers to that portion of the hard palate that is formed by the growth of the two palatine shelves medi ...

History

Nanictidopidae was named in 1956 by paleontologists

D. M. S. Watson Prof David Meredith Seares Watson FRS FGS HFRSE LLD (18 June 1886 – 23 July 1973) was the Jodrell Professor of Zoology and Comparative Anatomy at University College, London from 1921 to 1951. Biography Early life Watson was born in the Highe ...

and

Alfred Romer Alfred Sherwood Romer (December 28, 1894 – November 5, 1973) was an American paleontologist and biologist and a specialist in vertebrate evolution. Biography Alfred Romer was born in White Plains, New York, the son of Harry Houston Romer an ...

. Watson and Romer included many therocephalians in the family, including '' Blattoidealestes'', ''

Choerosaurus ''Choerosaurus'' is an extinct genus of therocephalian therapsids from the Late Permian of South Africa. The type species ''Choerosaurus dejageri'' was named by South African paleontologist Sidney H. Haughton from the ''Tropidostoma'' Assemblage ...

'', ''

Hofmeyria :''Distinguished from the Late Permian junior synonym of Akidnognathus "Hofmeyria".'' ''Hofmeyria'' is an extinct genus of therocephalians. See also * List of therapsids This list of therapsids is an attempt to create a comprehensive listing ...

'', and '' Promoschorhynchus''. These therocephalians have since been split up among other families like

Hofmeyriidae Hofmeyriidae is a family of therocephalian therapsids. It includes the genus '' Ictidostoma''. References External links Hofmeyriidaein the Paleobiology Database The Paleobiology Database is an online resource for information on the distrib ...

and

Akidnognathidae Akidnognathidae is an extinct family of therocephalian therapsids from the Late Permian and Early Triassic of South Africa, Russia and China. The family includes many large-bodied therocephalians that were probably carnivorous, including ''Mosch ...

Paleobiology

Except for the canines, nanictidopids lack the large pointed teeth of carnivorous therocephalians. Nanictidopids are thought to have been herbivorous, but they lack the enlarged buccal or cheek teeth of most herbivores. Although wear facets indicate use, most teeth are small and would have served little function in processing plant material. Another adaptation toward herbivory is the development of horny plates on 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 sepa ...

, but nanictidopids show no evidence of this adaptation either. One of the few indications of diet comes from a broken and polished canine in a specimen of ''Purlovia''. In life, this tooth may have been broken and worn smooth as it was digging for food. Nanictidopids were most likely primitive herbivores, possibly fruit-eating.

References

{{Taxonbar, from=Q6963603 Eutherocephalians Lopingian first appearances Lopingian extinctions Prehistoric therapsid families