Lycosuchidae

Lycosuchidae is a family of therocephalians (an extinct type of therapsids, broader group which modern mammals belong to) known from fossils from what is now the Beaufort Group of South Africa and that lived during the Middle to Late Permian between roughly 265 to 258 million years ago. It currently includes only two genera each with a single species, Lycosuchus, represented by L. vanderrieti, and Simorhinella, represented by S. baini, both named by paleontologist Robert Broom in 1903 and 1915, respectively (though Simorhinella was not recognised as a lycosuchid until 2014). Both species are large predators characterised by their size, reduced tooth counts with large, almost "sabre toothed" canine teeth, and relatively short, broad and low snouts.

Lycosuchids were once thought to be defined by having two simultaneously functional pairs of canines, so-called "double canines", instead of a single pair of like in all other predatory therapsids (including predatory mammals). However, it has since been recognised that these actually represent overlap between an older pair and their alternated replacements in separate tooth sockets, and that fossils of lycosuchids with "double canines" in fact preserve teeth at different stages of growth and replacement. This is the same method of canine replacement used by other predatory therapsids, though the pattern appears to be unusual in lycosuchids as the alternating canines occur together more often compared to other predatory therapsids like other therocephalians and gorgonopsians.

Lycosuchids are among the earliest known therocephalians and are also thought to be the most basal. The Russian genus Gorynychus, containing two species, may also belong to the family, although this result is not typically recovered. Lycosuchids are only known from the upper Tapinocephalus and lower Endothiodon Assemblage Zones of the Karoo Basin, surviving the Capitanian mass extinction event between them that wiped out many other therapsid groups and ended the Middle Permian, but apparently only persisting as a "dead clade walking" that went extinct as ecosystems fully recovered, potentially competing with recently evolved large gorgonopsians.