Daeodon

The type species of Daeodon is D. shohonensis, which is based on a fragment of a lower jaw from the John Day Formation of Oregon. Several other species were assigned to the genus in the subsequent decades, like D. calkinsi, D. mento[9] and D. minor.[10] Since 1945, it had been suggested that two other taxa were actually junior synonyms of Daeodon,[11] but the formalization of this referral didn't take place until the work of Lucas et al. (1998).[7] Ammodon leidyanum, named by Cope's rival, O. C. Marsh, and Dinohyus hollandi,[12] a complete skeleton from the Agate Springs quarry of Nebraska,[13] were found to be indistinguishable from each other and in turn both were indistinguishable from D. shoshonensis.[7] With the exception of D. calkinsi, which was tentatively excluded from Daeodon, the other previously recognized species of Daeodon were also synonymized to D. shoshonensis.[7] That same year, an obscure entelodont, Boochoerus humerosum, was also synonymized to Daeodon by Foss and Fremd (1998) and, albeit its status as a distinct species was retained, they note that the differences could still be attributed to individual or population variation or sexual dimorphism.[14]

Daeodon had a wide range in North America, with many fossils found in Agate Fossil Beds, representing an environment in a transition period between dense forests and expansive prairie, likely a major cause of their extinction in the middle Miocene.[16] It adapted to the grassland with a more cursorial body plan than more basal entelodonts like Archaeotherium, losing their dewclaws entirely, proximally fused metacarpals, and similar shoulder musculature to bison. [17][15]

Diet

Daeodon was omnivorous like all other entelodonts. Enamel patterns suggest eating of nuts, roots, and vines. The superficial similarity to peccaries, hippos, and bears implies a wide range in terms of what plants Daeodon may have been eating. The dry seasons of North America at the time could get very harsh, so they may have supplemented their water intake by eating grape vines. The extent of its carnivory is debated, but tooth wear suggests they specialized in crushing bone and ripping meat, and bite marks on chalicothere bones suggest they either hunted or scavenged large herbivores. Foss (2001) argues its head was far too heavy to be effective in taking down large prey so it must have relied exclusively on scavenging, but its bison-like adaptations for running, the stereoscopic vision characteristic of predators, and evidence of predation in entelodonts calls this interpretation into question.[18] The uncertainty of their diets suggests they were likely opportunistic omnivores similar to bears, eating whatever they need depending on the circumstance. [19]

Behavior

Entelodonts partook in intraspecific face biting, known from tooth marks on their skulls. Males would fight for dominance, possibly using their mandibular tubercles as protection in addition to their function as muscle attachments.[19] Sexual dimorphism of the exists jugal protections exist in Archaeotherium, and with a smaller Daeodon sample size, such dimorphism can't be ruled out for Daeodon. If dimorphic, the function of the expanded jugals was likely for display, supporting large preorbital glands similar to forest hogs used for chemical communication.