A New Large Hyainailourine from the Bartonian of Europe and Its Bearings on the Evolution and Ecology of Massive Hyaenodonts (Mammalia)

Abstract

We describe a new large-sized species of hypercarnivorous hyainailourine–Kerberos langebadreae gen. & sp. nov.–from the Bartonian (MP16) locality of Montespieu (Tarn, France). These specimens consist of a skull, two hemimandibles and several hind limb elements (fibula, astragalus, calcaneum, metatarsals, and phalanges). Size estimates suggest K. langebadreae may have weighed up to 140 kg, revealing this species as the largest carnivorous mammal in Europe at that time. Besides its very large size, K. langebadreae possesses an interesting combination of primitive and derived features. The distinctive skull morphology of K. langebadreae reflects a powerful bite force. The postcranial elements, which are rarely associated with hyainailourine specimens, indicate an animal capable of a plantigrade stance and adapted for terrestrial locomotion. We performed the first phylogenetic analysis of hyainailourines to determine the systematic position of K. langebadreae and to understand the evolution of the group that includes other massive carnivores. The analysis demonstrates that Hemipsalodon, a North American taxon, is a hyainailourine and is closely related to European Paroxyaena. Based on this analysis we hypothesize the biogeographic history of the Hyainailourinae. The group appeared in Africa with a first migration to Europe during the Bartonian that likely included the ancestors of Kerberos, Paroxyaena and Hemipsalodon, which further dispersed into North America at this time. We propose that the hyainailourines dispersed into Europe also during the Priabonian. These migrants have no ecological equivalent in Europe during these intervals and likely did not conflict with the endemic hyaenodont proviverrines. The discovery of K. langebadreae shows that large body size appears early in the evolution of hyainailourines. Surprisingly, the late Miocene Hyainailouros shares a more recent common ancestor with small-bodied hyainailourines (below 15 kg). Finally, our study supports a close relationship between the Hyainailourinae and Apterodontinae and we propose the new clade: Hyainailouridae.

Whence the beardogs? Reappraisal of the Middle to Late Eocene ‘Miacis’ from Texas, USA, and the origin of Amphicyonidae (Mammalia, Carnivora)

“…Curiously, amphicyonids are absent from the latest-Uintan to early-Duchesnean assemblages west of the Rocky Mountain region (e.g. Hancock Quarry l.f. (Clarno Formation) of Oregon, Laguna Riviera and Pearson Ranch l.f. (Santiago and Sespe Formations) of southern California), which include some of the oldest North American occurrences of immigrant carnivore lineages from Eurasia (represented by hyaenodontids Hemipsalodon and Hyaenodon and a nimravid[99][100][101]), and of an early non-canoid carnivoraform, Lycophocyon[14,102].…”

The first North AmericanPropterodon(Hyaenodonta: Hyaenodontidae), a new species from the late Uintan of Utah

“…The Pterodon spp. OTU was restricted to P. dasyuroides and rescored, given that new evidence indicates Pterodon , as traditionally defined, is likely polyphyletic (Solé et al, 2015a; Borths & Stevens, 2019a; Borths & Stevens, 2019b). Three additional taxa were added to the matrix, Boritia duffaudi , Preregidens langebadrae , and Matthodon menui .…”

The neurocranium of Ekweeconfractus amorui gen. et sp. nov. (Hyaenodonta, Mammalia) and the evolution of the brain in some hyaenodontan carnivores

“…The body mass of Proviverra typica was estimated by Dubied et al (2019) using average lower molar length (Morlo, 1999) of another individual of the same species. The body mass of Paroxyaena pavlovi is thought to be similar to that of P. galliae based on M1 size (Solé et al, 2015b). The body mass of H. brachyrhynchus is not currently known.…”

“…Order HYAENODONTA Van Valen, 1967 Superfamily HYAINAILOUROIDEA Pilgrim, 1932 sensu Solé, Amson, Borths, Vidalenc, Morlo, andBastl, 2015b Family TERATODONTIDAE Savage, 1965Subfamily TERATODONTINAE Savage, 1965 , 4).…”

“…Phylogenetic Position of Ekweeconfractus amorui-The phylogeny of Hyaenodonta has been the subject of a series of studies in the past decade (Solé et al, 2014;Solé et al, 2015b;Borths et al, 2016;Borths and Seiffert, 2017;Stevens, 2017, 2019;Dubied et al, 2019). Our object herein has not been to establish a new phylogeny and, in view of the cited ongoing work, we have not attempted an independent assessment of hyaenodont phylogeny.…”