''Nikkasaurus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of therapsids first named and described by Ivakhnenko.

Description

''Nikkasaurus'', named after Russian paleontologist Nikolay Kalandadze, was a small therapsid, with a

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

about 5 cm long. The

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

s had large

orbits In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificia ...

and sclerotic rings, and the head was tilted back, as with all therapsids. The skull looks superficially similar to those of the

pelycosaurs Pelycosaur ( ) is an older term for basal or primitive Late Paleozoic synapsids, excluding the therapsids and their descendants. Previously, the term mammal-like reptile was used, and Pelycosauria was considered an order, but this is now thoug ...

, in particular members of

Varanopidae Varanopidae is an extinct family (biology), family of amniotes known from the Late Carboniferous to Middle Permian that resembled monitor lizards (with the name of the group deriving from the monitor lizard genus ''Varanus'') and may have filled ...

Biology

''Nikkasaurus'' was probably mainly

insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores we ...

, and possibly

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

Systematics

The only known species is the type species ''N. tatarinovi'', described by MF Ivahnenko in 2000, from the

Middle Permian The Guadalupian is the second and middle series/epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and Texas, and dates between 272.95 ± 0. ...

Mezen River Basin. ''Nikkasaurus'' is possibly a relic of a more ancient stage of therapsid development.M. F. Ivakhnenko. 2008. Podklass Ophiacomorpha. In M. F. Ivakhnenko and E. N. Kurochkin (eds.), Iskopaemye pozvonotchnye Rossii i sopredel'nykh stran: Iskopaemye reptilii i ptitsy, Tchast' 1 ossil vertebrates of Russia and adjacent countries: Fossil reptiles and birds, Part 1 GEOS, Moscow 95-100

References

* Kemp, Thomas Stainforth (2005). ''The Origin and Evolution of Mammals''. . Prehistoric therapsid genera Guadalupian synapsids of Europe Guadalupian genus first appearances Guadalupian genus extinctions Permian Russia Fossils of Russia Fossil taxa described in 2000 {{paleo-therapsid-stub

Description

Biology

Systematics

See also

References