OURS ET BELETTE. DENTS DE SABRE DANS LA NUIT. Deux espèces de protomammifères à dents de sabre du Permien, non répertoriées en tant que telles jusqu'à présent, viennent d'être découvertes près de la ville de Kotelnich (oblast de Kirov) le long de la rivière Vyatka (sous - affluent de la Volga). Ces deux prédateurs étaient probablement de moeurs nocturnes. Ils ont reçu leurs noms en lien avec ceux de monstres légendaires du "folklore" russe. Gorynichus masyutinae avait la taille d'un loup, C'était un therocéphalien. Nochnitsa geminidens était beaucoup plus petit. C'était un gorgonopsien. Après la phase d'extinction du permien médian, il y a 260 millions d'années, il y a eu un basculement complet entre les deux groupes. Jusqu'alors, les prédateurs dominants étaient des gorgonopsiens géants, du volume d'un tigre à dents de sabre, alors que les therocéphaliens étaient beaucoup plus petits. Après cette épisode, les therocéphaliens sont devenus dominants, comme si les belettes étaient devenues des ours, et les ours des belettes.
https://www.sciencedaily.com/releases/2018/06/180608085622.htm
Christian F. Kammerer, Vladimir Masyutin. A new therocephalian (Gorynychus masyutinae gen. et sp. nov.) from the Permian Kotelnich locality, Kirov Region, Russia. PeerJ, 2018.
Recent expeditions by the Vyatka Paleontological Museum have collected a wealth of spectacularly-preserved Permian fossils near the town of Kotelnich along the Vyatka River in European Russia. These fossil discoveries include the remains of two previously unknown species of predatory protomammals, newly described in the journal PeerJ by Christian Kammerer of the North Carolina Museum of Natural Sciences and Vladimir Masyutin of the Vyatka Paleontological Museum. The first of the two new species, Gorynychus masyutinae, was a wolf-sized carnivore representing the largest predator in the Kotelnich fauna. The second new species, Nochnitsa geminidens, was a smaller, long-snouted carnivore with needle-like teeth. Gorynychus belongs to a subgroup of protomammals called therocephalians ("beast heads"), whereas Nochnitsa belongs to a different subgroup called gorgonopsians ("gorgon faces").
Both new species are named after legendary monsters from Russian folklore, befitting their menacing appearances. Gorynychus is named after Zmey Gorynych, a three-headed dragon, and Nochnitsa is named after a malevolent nocturnal spirit. (Based on their relatively large eye sockets, it is likely that Nochnitsa and its relatives were nocturnal.)
Gorynychus and Nochnitsa improve scientists' understanding of ecosystem reorganization after the mid-Permian extinction (260 mya). Although not as well-known as the more devastating end-Permian mass extinction (252 mya, which nearly wiped out protomammals), the mid-Permian mass extinction also played a major role in shaping the course of protomammal evolution. In typical late Permian ecosystems, the top predators were giant (tiger-sized), saber-toothed gorgonopsians and therocephalians were generally small insectivores. In mid-Permian ecosystems, by contrast, these roles are reversed. At Kotelnich, the saber-toothed top predator Gorynychus is a therocephalian and the only gorgonopsians are much smaller animals.
"In between these extinctions, there was a complete flip-flop in what roles these carnivores were playing in their ecosystems -- as if bears suddenly became weasel-sized and weasels became bear-sized in their place," says Kammerer. The new species from Russia provide the first evidence that there was a worldwide turnover in predators after the mid-Permian extinction, and not just a localized turnover in South Africa.
Kammerer adds, "Kotelnich is one of the most important localities worldwide for finding therapsid fossils -- not only because they are amazingly complete and well-preserved there, but also because they provide an all-too-rare window into mammal ancestry in the Northern Hemisphere during the Permian."
