Brazilian fossils reveal homoplasy in the oldest mammalian jaw joint.

ABSTRACT: The acquisition of the load-bearing dentary-squamosal jaw joint was a key step in mammalian evolution^1-5. Although this innovation has received decades of study, questions remain over when and how frequently a mammalian-like skull-jaw contact evolved, hindered by a paucity of three-dimensional data spanning the non-mammaliaform cynodont-mammaliaform transition. New discoveries of derived non-mammaliaform probainognathian cynodonts from South America have much to offer to this discussion. Here, to address this issue, we used micro-computed-tomography scanning to reconstruct the jaw joint anatomy of three key probainognathian cynodonts: Brasilodon quadrangularis, the sister taxon to Mammaliaformes^6-8, the tritheledontid-related Riograndia guaibensis⁹ and the

SUBMITTER: Rawson JRG 

PROVIDER: S-EPMC11464377 | biostudies-literature | 2024 Oct

REPOSITORIES: biostudies-literature