Chasmaporthetes sp.: The first evidence of Hyenas within the Arctic Circle.

Hyenas first appeared in Eurasia in the Early Miocene, and rapidly diversified to become the most abundant predators in Eurasia, with more than 60 described species. At some point during the Plio-Pleistocene Hyenas reached North America, becoming common in the southern United States and Mexico during the Pleistocene, before disappearing there during the End Pleistocene Megafaunal Extinction. Hyenas are thought, like many other Mammal groups, to have reached the Americas via the Beringian Land Bridge, which connected Alaska to the Russian Far East during periods of low sealevel associated with the Pleistocene glaciations. However, to date this has been an entirely theoretical movement, with Hyena remains unknown from northern parts of the United States or Canada.

In a paper published in the journal Open Quaternary on 18 June 2019, Jack Tseng of the University at Buffalo, Grant Zazula of the Government of Yukon, and of Research and Collections at the Canadian Museum of Nature, and Lars Werdelin of the Swedish Museum of Natural History describe the first recorded Hyena specimens from the Pleistocene deposits of the Old Crow Basin, in the unglaciated region of northern Yukon Territory, Canada.

The material described comprises two isolated teeth, probably belonging to the species Chasmaporthetes ossiphragus, and certainly to a member of the genus Chasmaporthetes, from the CRH 11A locality, on a point bar near the downstream end of the basin. Over 50 000 reworked fossils from at least 80 vertebrate species have been recovered from point bars on the Old Crow River. The material is thought to be between 1.4 million and 12 000 years in age, but almost certainly more than 850 000 years old and probably closer to 1.4 million years old.

Hyena fossils from Old Crow, Yukon Territory, Canada. Chasmaporthetes cf. Chasmaporthetes ossifragus, CMN 24958, right p3: (A) lingual stereopair views, (B) labial stereopair views, (C) occlusal stereopair views. CMN 38053, left m1: (D) labial stereopair views, (E. lingual stereopair views, (F) occlusal stereopair views. Tseng et al. (2019).

The genus Chasmaporthetes has previously been recorded in buth Asia and North America, to its discovery in the Beringia region is not unexpected, though the most northerly American specimen previously discovered comes from Meade County in Kansas, more than 4000 km to the south, while the closest Asian specimens come from Shamar in Mongolia, roughly 6500 km away, with the distance between the two sites being over 10 000 km.

Fossil localities containing Chasmaporthetes. New material described in this study from Old Crow Basin (Locality 11A) is marked with a star. Dashed arrows indicate likely dispersal route evidenced by new fossils. Regions with more than one fossil locality are indicated with a quantity after the locality marker. Tseng et al. (2019).

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An American Hyaenodontid in China.

The Hyaenodontidae were a group of carnivorous Mammals the appeared in the the Late Palaeocene and continued till the Late Miocene. Their name means 'Hyena-toothed', though they are not closely related to the Hyenas, or any other extant Mammal group. They were formerly classified with the Oxyaenids in a group called the Creodonts, though that group is now thought to be polyphyletic; i.e. the two groups which formerly were classified together to form the Creodonts are no longer thought to be closely related.

In a paper published in the journal Palaeontology in January 2014, Michael Morlo of the Forschungsinstitut Senckenberg, Katharina Bastl of the Institut für Paläontologie and the Forschungsgruppe Aerobiologie und Polleninformation at Universität Wien, Wu Wenhao of the  Research Center of Palaeontology at Jilin University and Stephan Schaal, also of the Forschungsinstitut Senckenberg, describe a new species of Hyaenodontid from the late middle Eocene Huadian Formation of Jilin Province China.

The new species is placed in the genus Sinopa, and given the specific name jilinia, meaning ‘from Jilin’. The species is described from a right dentary (jawbone) preserved in two fragments, recovered from the Gonglangtou Coal Mine in Jilin Province.

Right dentary of Sinopa jilinia from Gonglangtou, late middle Eocene. (A) labial view, (B) occlusal view, (C) lingual view of the main part of the right hemimandible with m1–3, (D) labial view, (E) lingual view, (F) occlusal view of the smaller fragment of the right hemimandible with p2–p3. Note m3 smaller than m1, backward leaning protoconids, very labially postvallid origin of cristid obliquum and continuous labial cingulids in all molars. Morlo et al. (2014).

The genus Sinopa has previously been described only from North America; this is its first occurrence in Asia. The presence of Hyenadontids in China is not unexpected; the group is believed to have arisen in Africa, and spread through Eurasia to North America by the early Eocene, however the genus Sinopa is thought to have arisen in North America, after faunal interchange with eastern Asia had largely ceased. The presence of Sinopa jilinia in northeast China adds to a small, but growing, body of evidence that faunal interchange between Asia and North America may have persisted for longer than previously thought. 

See also A new species of Leptictid Mammal from the Late Eocene of South Dakota, A new species of Hyaenodontidan Mammal from the Early Eocene of France and Three new species of Tapir from the Early Eocene of Pakistan.

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A new species of Hyaenodontidan Mammal from the Early Eocene of France.

The Hyaenodontidae were a group of carnivorous Mammals the appeared in the the Late Palaeocene and continued till the Late Miocene. Their name means 'Hyena-toothed', though they are not closely related to the Hyenas, or any other extant Mammal group. They were formerly classified with the Oxyaenids in a group called the Creodonts, though that group is now thought to be polyphyletic; i.e. the two groups which formerly were classified together to form the Creodonts are no longer thought to be closely related.

In a paper published in the Journal of Systematic Palaeontology on 11 December 2012, Floréal Solé of the Muséum national d’Histoire naturelle in Paris describes a new species of Hyaenodontid from the Early Eocene of France.

The new species is named Morlodon vellerei, where 'Morlodon' means 'Morlo's tooth', honouring Michael Morlo of the Senckenberg Research Institute, an expert on carnivorous Mammals, and 'vellerei' means 'to scrape'. The species is based upon 21 fragmentary specimens from Saint-Agnan, Avenay and Condé-en-Brie. Only the teeth and parts of the jaws are known.

Morlodon velleri. (A–C) Left lower jaw bearing P2, P3, P4, M1 andM2 and roots of C1–P1; (A) lingual view; (B) labial view; (C) occlusal view. (D–G) Left maxillary bearing M2 and right maxillary bearing P4, M1, M2 and M3; (D) occlusal view of the right maxillary; (E) occlusal view of the left maxillary; (F) lingual view of the right maxillary; (G) lingual view of the left maxillary. Scale bar is 1 cm. Solé (2012).

See also A new species of fossil Pig from the early Pleistocene of Ethiopia, A new species of Red Toothed Shrew from the Early Pleistocene of Poland, The diet of the Langebaanweg Hyaenids, Fossil Pandas from the Middle Miocene of Spain and A Giant Camel from the mid-Pliocene of Ellesmere Island in the Canadian Arctic.

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