Functional morphology and biomechanics of an ontogenetic series of the Triassic cynodont <em>Brasilodon quadrangularis</em> and bite performance in the sister taxon of Mammaliformes

The Santa Maria Supersequence in Brazil has yielded numerous cynodont species from the Late Triassic, including derived probainognathians, which are relevant for the understanding of the cynodont-mammal transition. One of these cynodonts is Brasilodon quadrangularis, considered to be the sister taxon to Mammaliaformes due to a suite of apomorphic features in the skull, dentition, and postcranium. Specimens referred to this species have been described in detail, representing different ontogenetic stages. However, we know little of the functional performance and skull mechanics of this species and how this relates to recent studies of cynodont-mammaliaform skull mechanics. Here, we use beam analysis and finite element analysis (FEA) to assess the function of the skulls of *Brasilodon and compare their functional performance to that of the early mammaliaforms Morganucodon and Kuehneotherium. The ontogenetic series of Brasilodon shows a trend of increasing overall jaw strength and resistanc..., , # Data from: Functional morphology and biomechanics of an ontogenetic series of the Triassic cynodont *Brasilodon quadrangularis* and bite performance in the sister taxon of Mammaliformes Dataset DOI: [10.5061/dryad.8kprr4z0m](10.5061/dryad.8kprr4z0m) ## Description of the data and file structure CT scans were taken of five specimens of *Brasilodon* (UFRGS-PV-628-T, UFRGS-PV-760-T, UFRGS-PV-929-T, UFRGS-PV-1030-T, and UFRGS-PV-1043-T) representing different ontogenetic stages. The dentary bones of these specimens were segmented to be used in functional morphological and biomechanical analyses and to determine changes in the ontogenetic series and compare bite performance. Interdental slices of all of these specimens were used in beam analysis to determine the strength of the mandible. The skull (i.e., cranium and mandible) of UFRGS-PV-1043-T was used to reconstruct temporalis and masseter muscles for finite element analysis on the most complete segmented dentary meshes of the juvenil...,