Question: Information:  - Reptiles are tetrapod (four-limbed vertebrate) animals in the class Reptilia, comprising today's turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. The study of these traditional reptile orders, historically combined with that of modern amphibians, is called herpetology.  - Styracocephalus platyrhynchus ( ' spike head ' ) is an extinct species of tapinocephalian therapsid that lived during the Guadalupian epoch . Styracocephalus ' head ornament meant that it could be recognised from a distance . The most striking feature of Styracocephalus are the large backward - protruding tabular horns . The crest stuck upwards and backwards , but there is some variation in its shape , and this suggests that it changed throughout life and that it may be sexually dimorphic . Styracocephalus was a herbivore that may have been fully terrestrial or partly aquatic like the modern hippopotamus . It may have evolved from the estemmenosuchids . Its remains are known from South Africa but it probably had a wider distribution . It was around 1.8 metres ( 5 ft 11 in ) in length , with a 42 centimetres ( 17 in ) long , 29 centimetres ( 11 in ) wide skull .  - Mammals are any vertebrates within the class Mammalia (from Latin "mamma" "breast"), a clade of endothermic amniotes distinguished from reptiles and birds by the possession of a neocortex (a region of the brain), hair, three middle ear bones and mammary glands. The sister group of mammals may be the extinct "Haldanodon." The mammals represent the only living Synapsida, which together with the Sauropsida form the Amniota clade. The mammals consist of the Yinotheria including monotrema and the Theriiformes including the theria.  - Synapsids (Greek, 'fused arch'), synonymous with theropsids (Greek, 'beast-face'), are a group of animals that includes mammals and every animal more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having a temporal fenestra, an opening low in the skull roof behind each eye, leaving a bony arch beneath each; this accounts for their name. Primitive synapsids are usually called pelycosaurs or pelycosaur-grade synapsids; more advanced mammal-like ones, therapsids. The non-mammalian members are described as mammal-like reptiles in classical systematics; they can also be called stem mammals or proto-mammals. Synapsids evolved from basal amniotes and are one of the two major groups of the later amniotes; the other is the sauropsids, a group that includes modern reptiles and birds. The distinctive temporal fenestra developed in the ancestral synapsid about 312 million years ago, during the Late Carboniferous period.  - Tapinocephalus ("humble head") is a genus of large herbivorous dinocephalian that lived during the Middle Permian Period. These stocky, barrel-bodied animals were characterised by a massive bony skull roof and short weak snout. It is thought that, like the rest of the members of its family, the animals engaged in head-butting intraspecific behavior, possibly for territory or mates.  The fossil remains (skull and postcranial elements) of "Tapinocephalus" are known from the Lower, Middle, and Upper part of the "Tapinocephalus" Assemblage Zone (Capitanian age) of the Lower Beaufort Beds of the South African Karoo. Only the type species, "T. atherstonei" is now considered valid for this genus.  - Tapinocephalia is one of the major groups of dinocephalian therapsids and the major herbivorous group. Tapinocephalia is thought to consist of three clades: Styracocephalidae, Titanosuchidae, and the very successful Tapinocephalidae. Notable tapinocephalians include "Moschops", "Tapinocephalus", and "Titanosuchus".  - Therapsida is a group of synapsids that includes mammals and their ancestors. Many of the traits today seen as unique to mammals had their origin within early therapsids, including having their four limbs extend vertically beneath the body, as opposed to the sprawling posture of other reptiles. The earliest fossil attributed to Therapsida is "Tetraceratops insignis" from the Lower Permian.     What object entity has the relation of 'taxon rank' with the subject 'styracocephalus'?   Choices: - class  - genus  - group
Answer:
genus