Peignecyon

The mandible of this taxon is quite similar to that of a wolf, but shorter and more robust. Albeit its morphology still resembles that of the Amphicyoninae, Peignecyon shows clear adaptions towards hypercarnivory, which are more developed than in earlier thaumastocyonines such as Ysengrinia. The most notable of these is the long diastema, which is associated with the reduction of the second and third lower premolars. The fourth premolar has a distally inclined, high protoconid, but it is small compared to the first molar. The short talonid of the latter is dominated by the hypoconid, and is of similar width to the trigonid. The mesial cristids of the protoconid, paraconid, and the strongly developed hypoconid are aligned to form the carnassial blade. The metaconid is strongly diminished. All these features show that it possessed moderately sectorial carnassials. Both the lower and upper second molar are reduced in size, with the lower one having a quadrangular shape. The m3 is even smaller than the m2. The lingual area of the M1 is also strongly reduced, a feature typical of more derived members of the subfamily. Its canine is well-developed, with a sharp distal cristid.^[3] The shortening of the rostrum and the reduction of the premolars in thaumastocyonines is reminiscent of felids.^[6]

The body mass of this species has been estimated at 110 kg.^[7]

Peignecyon has so far only been discovered at Tuchořice, an early Miocene locality which dates to MN3. The site preserves a riparian forest dominated by maples. Date palms and lianas also occur, indicating a warm climate, in which temperatures did not fall under 18°C. Hot minerals springs shaped the site, at which an abundant amount of fossils belonging to various carnivorans were found. This can likely be explained by the 'trapping effect': Predators were attracted to the carcasses of herbivores killed by the gases released by the mineral springs, only to succumb to the carbon dioxide themselves.^[1] Besides Peignecyon, three more amphicyonids were discovered: the large amphicyonines Paludocyon bohemicus and Amphicyon carnutense, and the small Dehmicyon schlosseri. Other carnivorans include the small ursids Ballusia and Ursavus, as well as the larger Hemicyon, the viverrid Semigenetta and a variety of mustelids and procyonids.^[2] Among the larger mammals are three species of rhinoceros, belonging to the genera Prosantorhinus, Protaceratherium and Aceratherium.^[8] Other herbivores include chalicotheres, the suid Aureliachoerus, the anthracothere Brachyodus, and the ruminants Palaeomeryx, Lagomeryx, and Amphitragulus. The small-mammal assemblage is dominated by sciurids, but various eomyids, glirids, shrews, and beavers are also present. Non-mammalian fossils include abundant turtle remains, and various accipitrids, the latter of which were likely met their demise due to the same 'trapping effect' as their mammalian counterparts.^[1][9]