Bonacynodon

Bonacynodon is an extinct genus of cynodonts that lived in what is now southern Brazil during the Triassic period (Ladinian–Carnian ages). The genus is monotypic, containing only the type species Bonacynodon schultzi. B. schultzi is known from two specimens, consisting of two partial skulls and some badly preserved parts of the postcranium. Both specimens were recovered from the Pinheiros-Chiniquá Sequence, part of the Santa Maria Supersequence of the Paraná Basin. This sequence preserves a faunal association known as the Dinodontosaurus Assemblage Zone, which contains numerous other species of cynodonts, dicynodonts and reptiles. Bonacynodon was a small, likely insectivorous cynodont, whose length has been estimated at around . It can be distinguished from other cynodonts by its large, serrated (saw-like) canine teeth. Together with the genus Probainognathus of Argentina, it made up the family Probainognathidae, one of the earliest-diverging lineages of the clade Probainognathia. It was a fairly close relative of mammals, the only group of cynodonts alive today.

== Discovery and naming == thumb|left|alt=Refer to caption|Map showing the Middle to Late Triassic outcrops of the municipalities of Candelária, Rio Grande do Sul|Candelária and [[Santa Cruz do Sul. Both specimens of Bonacynodon were collected from the Pinheiros region, shown on the left side of the map.]]