A new bauriamorph therocephalian adds a novel component to the Lower Triassic tetrapod assemblage of the Fremouw Formation (Transantarctic Basin) of Antarctica

The origin and evolution of Cynodontia (Synapsida, Therapsida): Reassessment of the phylogeny and systematics of the earliest members of this clade using 3D‐imaging technologies

“…Like most other major therapsid clades, Therocephalia, a species-rich and ecomorphologically varied group, first diversified during the middle Permian and showed its highest diversity in the late Permian (e.g., Abdala et al, 2008;Day & Smith, 2020;Huttenlocker & Smith, 2017;Kammerer, 2023;Pusch et al, 2020;Smith, 2020;Viglietti, 2020). This lineage has generally been considered as monophyletic by recent authors (Hopson & Barghusen, 1986;Huttenlocker, 2009;Huttenlocker & Sidor, 2016Huttenlocker & Smith, 2017;Liu & Abdala, 2019Pusch et al, 2021Pusch et al, , 2023Sidor et al, 2022;van den Heever, 1994). By contrast, Abdala (2007) and Botha et al (2007) recovered Therocephalia as paraphyletic, with the whaitsiid Theriognathus as the F I G U R E 1 2 (a-q) Three-dimensional reconstruction of the brain endocast (in blue) with reconstructed inner ear labyrinth (in red) in the eutheriodonts studied in right lateral (top), posterior (bottom), and dorsal (right) views.…”

“…The absence of cynodonts in middle Permian strata has led some researchers to propose that cynodonts are in fact derived from within Therocephalia, with their closest relatives being members of the family Whaitsiidae, rendering Therocephalia paraphyletic (Abdala, 2007; Abdala et al, 2008; Botha et al, 2007; Kemp, 1972). However, more recent phylogenetic analyses of therocephalians and early cynodonts (e.g., Huttenlocker, 2009; Huttenlocker & Sidor, 2016, 2020; Huttenlocker & Smith, 2017; Liu & Abdala, 2019, 2020, 2022; Pusch et al, 2021, 2023; Sidor et al, 2022) support reciprocal monophyly of Cynodontia and Therocephalia, implying a ghost lineage of as much as 10 million years between the earliest therocephalian records and the first appearance of Cynodontia (Angielczyk & Kammerer, 2018). Despite the generally consistent recent recovery of this topology, it must be noted that this relationship is poorly supported, typically requiring only a few additional steps to pull cynodonts into Therocephalia.…”