Trucidocynodon

Trucidocynodon is an extinct genus of ecteniniid cynodonts from Upper Triassic of Brazil. It contains a single species, Trucidocynodon riograndensis. Fossils of "Trucidocynodon" were discovered in Santa Maria Formation outcrops in Paleorrota geopark Agudo. "T. riograndensis" was similar to "Ecteninion lunensis" from the Upper Triassic Ischigualasto formation of Argentina, but differed in several respects, including its larger size. It is known from a nearly complete holotype skeleton as well as a referred skull. The holotype skeleton had an estimated length of 1.2 meters (4 feet), while the referred skull was 17% larger than that of the holotype. "Trucidocynodon" is considered one of the largest known carnivorous cynodonts from the Triassic, as well as one of the largest probainognathians in the entire Mesozoic.
A biomechanical study has argued that "Trucidocynodon" not only had erect limbs, but that it also possibly had digitigrade forelimbs, being among the first synapsids to show adaptations for cursoriality. However, it was likely not a specialized runner, unlike ungulates and some other modern cursorial mammals.