Eutherocephalia

Eutherocephalia Temporal range: Late Permian-Middle Triassic, 260–242.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Life restoration of the eutherocephalian Moschorhinus preying on the dicynodont Lystosaurus.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Clade:	Therapsida
Clade:	†Therocephalia
Clade:	†Scylacosauria
Clade:	†Eutherocephalia Hopson and Barghusen, 1986
Families and genera
Caodeyao Chthonosaurus Ichibengops Scylacosuchus Akidnognathidae Hofmeyriidae Nanictidopidae Whaitsiidae Baurioidea

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 became extinct by the end of the Permian period, eutherocephalians survived the Permian–Triassic extinction event. The group eventually became extinct in the Middle Triassic.

Characteristics

The Eutherocephalians evolved several mammal-like traits through convergent evolution with Cynodontia. Among those traits were the loss of palatine teeth and the reduction of the parietal eye.^[1] The latter organ is instrumental in thermoregulation among lizards and snakes, indicating both eutherocephalians and cynodonts were evolving toward a more active, homeothermic lifestyle, though the eye never fully disappeared in the eutherocephalians.^[2]

Classification

The clade Eutherocephalia contains the majority of therocephalians, yet the phylogenetic relations of the groups within it remain unclear. Eutherocephalia is supported as a true clade in many phylogenetic analyses, but the placement of groups like Akidnognathidae, Hofmeyriidae, Whaitsiidae, and Baurioidea, all of which lie within Eutherocephalia, remains debated.^[1]

References

1. Rubidge, B.S.; Sidor, C.A. (2001). "Evolutionary patterns among Permo-Triassic therapsids" (PDF). Annual Review of Ecology, Evolution, and Systematics. 32: 449–480. doi:10.1146/annurev.ecolsys.32.081501.114113. Archived from the original (PDF) on 2012-03-21.
2. Benoit, Julien; Abdala, Fernando; Manger, Paul; Rubidge, Bruce (2016). "The sixth sense in mammalians forerunners: variability of the parietal foramen and the evolution of the pineal eye in South African Permo-Triassic eutheriodont therapsids". Acta Palaeontologica Polonica. doi:10.4202/app.00219.2015. Retrieved 23 June 2020.