BITE MARKS ON NIMRAVID CRANIA AND IMPLICATIONS FOR INTRACLADE INTERACTIONS WITHIN NIMRAVIDAE (MAMMALIA: FELIFORMIA)

Evidence of intraclade combat among nimravids was first reported in 1936 based on a single specimen of Nimravus (SDSM 348) that preserves a prominent puncture mark on the frontal. Since that report, the topic of intraclade combat amongst nimravids received little attention. Examination and preparation of relatively complete crania preserved in the collections at the South Dakota School of Mines and Technology and at Badlands National Park revealed an additional four specimens (two of Dinictis and two of Hoplophoneus) that display bite marks referable to other nimravids. Comparison of these bite marks reveals upper canine punctures are concentrated around the orbital region, with four of the specimens exhibiting damage to the medial wall of the orbit. Additionally, most upper canine punctures present within the frontals and parietals on these specimens are aligned so that the other canine would have inserted into the orbit and are often paired with punctures/extensive damage on the medial wall of the orbit. Relatively conical punctures consistent with the morphology of the lower canines are positioned more posteriorly on the skulls, most of which are present on the posterior surface of the nuchal crest or the anterior corner of the sagittal crest. The distribution of these bite marks indicates a consistent pattern of attack that was oriented from behind with a primary goal of blinding the target individual. This pattern of attack is consistent with the widely hypothesized need for saber-toothed feliforms to minimize impacting dense bone with their delicate upper canines, which could result in breakage. Only the frontal puncture originally reported on SDSM 348 shows evidence of healing, indicating that in most instances these attacks were fatal. Additionally, recent preparation work on SDSM 348 revealed a second set of bite marks along the right side of the skull that show no evidence of healing, suggesting this individual was subjected to a second, fatal attack. The fact that similar punctures are currently unreported from the crania of potential prey species suggests that relatively risky bites to the crania were restricted to cases where the risk of breaking their delicate upper canines was outweighed by the need to defend territory, social standing, or oneself against a competitor.