Bauriidae is an extinct family of therocephalian therapsids. Bauriids were the latest-surviving group of therocephalians after the Permian–Triassic extinction event, going extinct in the Middle Triassic. They are among the most advanced

eutherocephalia Eutherocephalia ("true beast head") is an extinct clade of advanced therocephalian therapsids. Eutherocephalians are distinguished from the lycosuchids and scylacosaurids, two early therocephalian families. While lycosuchids and scyalosaurids b ...

ns and possess several

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

-like features such as a secondary palate and wide postcanine teeth at the back of the jaws (analogous to mammalian molars). Unlike other therocephalians, bauriids were herbivorous. They were also smaller than earlier members of the group. Two subfamilies are classified within Bauriidae:

Nothogomphodontinae ''Nothogomphodon'' is a genus of therocephalian therapsids. It is classified within the family Bauriidae and placed within its own subfamily, Nothogomphodontinae. Description ''Nothogomphodon'' was unusual among therocephalians for its sectorial ...

and

Bauriinae Bauriinae is an extinct subfamily of therocephalian therapsids. It is one of two subdivisions of the family Bauriidae Bauriidae is an extinct family of therocephalian therapsids. Bauriids were the latest-surviving group of therocephalians afte ...

Description

Bauriids have a dentition characteristic of herbivores with the exception of ''

Nothogomphodon ''Nothogomphodon'' is a genus of therocephalian therapsids. It is classified within the family Bauriidae and placed within its own subfamily, Nothogomphodontinae. Description ''Nothogomphodon'' was unusual among therocephalians for its sectorial ...

''. There are four incisors on either side of the upper jaw. Like other therocephalians, bauriids have moderately enlarged canines. The postcanine teeth behind the canines are broad. The postcanines of the upper and lower jaw fit tightly together as an adaptation to processing plant material. An autapomorphy or unique feature of Bauriidae is the expansion of the

dentary bone In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable ...

of the lower jaw inward toward the jaw midline, forming a wide shelf of bone to either side of the tooth row. A similar expansion of the maxilla in the upper jaw is also seen in bauriids, although it is not unique to the group as the feature has also evolved in a group of

cynodont The cynodonts () (clade Cynodontia) are a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Cynodonts had a wide variety ...

therapsids called

gomphodont Gomphodontia is a clade of cynognathian cynodonts that includes the families Diademodontidae, Trirachodontidae, and Traversodontidae. Gomphodonts are distinguished by wide and closely spaced molar-like postcanine teeth, which are convergent w ...

s (which, like bauriids, were herbivorous).

Phylogeny

Bauriids belong to a large

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

or evolutionary grouping of therapsids called Therocephalia that is closely related to mammals (mammals are part of Cynodontia, the sister taxon of Therocephalia in most studies). Within Therocephalia, bauriids are part of a subgroup called

Eutherocephalia Eutherocephalia ("true beast head") is an extinct clade of advanced therocephalian therapsids. Eutherocephalians are distinguished from the lycosuchids and scylacosaurids, two early therocephalian families. While lycosuchids and scyalosaurids b ...

, which includes all but the most

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

therocephalians. Nested within Eutherocephalia is a clade called Baurioidea, of which bauriids are the most derived members (baurioids that fell outside Bauriidae were traditionally all placed within a group called Scaloposauria, but the group is now thought to be a

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

assemblage of basal baurioids). The inter-group relationships of Bauriidae are uncertain. Battail and Surkov (2003) split it into two subfamilies:

, which included the genus ''Nothogomphodon''; and

, which included all other bauriids. In his phylogenetic analysis of therocephalians, Huttenlocker (2014) found support for ''Nothogomphodon'' being more basal than other bauriids, but also found a clade containing ''

Ordosiodon ''Ordosiodon'' is an extinct genus of therocephalian therapsids from the Early Triassic of China. It includes two species, ''O. lincheyuensis'' and ''O. youngi''. ''O. lincheyuensis'', the type species, was named by Chinese paleontologist C. C. ...

'' and ''

Hazhenia ''Hazhenia'' is an extinct genus of therocephalian therapsids from the Early Triassic of China, of which ''Hazhenia concava'' is the only species. ''Hazhenia'' was named in 1981 from the Heshanggou Formation in the Ordos Desert of Inner Mongolia ...

'' (Chinese therocephalians that had previously been grouped together under the family Ordosiidae) to be the sister group of these other bauriids, with ''Nothogomphodon'' occupying a more basal position. Huttenlocker therefore restricted the name Bauriidae to the sister group of Ordosiidae. The cladogram below is modified from Huttenlocker (2014), showing the position of Bauriidae within Therocephalia and the interrelationships of bauriids supported by his analysis:

References

External links

Bauriidae
in the Paleobiology Database {{Taxonbar, from=Q4873580 Permian first appearances Middle Triassic extinctions Prehistoric therapsid families