Kerberos langebadreae

Kerberos ("Cerberus", after the multi-headed hellhound which guards the entrance to the Underworld) is an extinct genus of hyainailourid hyaenodonts in the subfamily Hyainailourinae, whose remains are known from France. The type and only known specimen was discovered in 1981 by Dominique Vidalenc, near the city of Lautrec in the Tarn department, in strata from the Sables du Castrais Formation. The specimen, consisting of a well-preserved skull, a lower jaw, and several limb elements, came from Montespieu, a fossil-bearing deposit dating to the Bartonian age of the Eocene; another hyaenodont, Cynohyaenodon, had been previously recovered from the same site. Kerberos was named in 2015 by a team consisting of Vidalenc and colleagues. One species of Kerberos, Kerberos langebadreae, has been described.

Kerberos was fairly large, with a mean estimated weight of 140 kg (310 lb), more than most of the hyaenodonts it shared its environment with. Its skull, when measured from the tip of its snout to the very back, was around 35 cm (14 in) in length, similar in size to that of a female brown bear. It had a fairly short snout and a tall sagittal crest, indicating that it had a powerful bite. Kerberos' premolars were adapted for crushing, while its molars appear to have been better suited for slicing. Certain aspects of its limb anatomy suggest that Kerberos walked with a plantigrade gait, that is to say one where the entire foot, including the heel, contacted the ground (as opposed to a digitigrade gait where only the toes contact the ground). This appears to be a primitive condition among hyainailourids, and many later genera, such as Simbakubwa, shifted to a semi-digitigrade gait.

The feeding ecology of Kerberos is believed to have been similar to that of modern striped and spotted hyenas. It was likely efficient both as an active hunter and as a scavenger, and, like other hyainailourines, wear patterns on its premolars suggest that it was capable of processing bone. It is a general trend that carnivores over about 25 kg (55 lb) often hunt prey with a body mass equal to or larger than themselves, so it is likely that Kerberos fed on some of the larger herbivores it coexisted with, such as Choeropotamus, Lophiodon, and Palaeotherium. It does not appear that Kerberos competed with the other hyaenodonts, namely hyaenodontids and proviverrines, with which it coexisted. Rather, as indicated by the lack of similarly sized mammalian predators, hyainailourines as a whole appear to have lacked direct ecological equivalents in Europe prior to their arrival, and thus occupied niches which were formerly left vacant.