Abstract
Amynodontidae is a family of Rhinocerotoidea (Mammalia, Perissodactyla) known from the late Early Eocene to the latest Oligocene, in North America and Eurasia. European Amynodontidae are very rare, and all remains belong almost exclusively to a single post—Grande Coupure genus from the Oligocene, Cadurcotherium. The “Grande Coupure” defines an extinctions and dispersal-generated originations event in Europe that is nearly contemporaneous with the Eocene-Oligocene transition. Perissodactyls are one of the major groups affected by this event: Palaeotheriidae went almost extinct during this crisis, whereas Rhinocerotidae appeared for the first time in Europe. Study of fossiliferous Eastern-European localities from this age is crucial for the understanding of this crisis. We report here three new localities of Amynodontidae in Eastern Europe. Two of them are dated from the Eocene (Morlaca, Romania; Dorog, Hungary), whereas the other is either Late Eocene or Early Oligocene (Dobârca, Romania). The skull from this latter locality belongs unexpectedly to the same individual as a previously described mandible attributed to “Cadurcodon” zimborensis. As a result, this specimen can be allocated to its proper locality, Dobârca, and is assigned to a new genus, Sellamynodon gen. nov. It is characterised by an extraordinary growth of the nuchal crest, a unique character among amynodontids. Along with this remarkable material from Dobârca, two specimens from another Romanian locality, Morlaca, have been recently discovered and are dated from the Late Eocene. They belong, as well as new material from Dorog (Middle Eocene, Hungary), to the genus Amynodontopsis, also found in North America. The new Hungarian material represents the earliest occurrence of Amynodontidae in Europe. New phylogenetic hypotheses of Rhinocerotoidea are proposed, including the new material presented here, and show that Amynodontidae may be closer to the polyphyletic family ʽHyracodontidaeʼ than to Rhinocerotidae. Amynodontidae, with their deep preorbital fossa and extremely reduced premolars, display in fact a very derived condition, compared to rhinocerotids.
Highlights
Amynodontidae is an extinct family of Perissodactyla that is generally included in the Rhinocerotoidea (e.g. [1–4])
The oldest representatives of the family Amynodontidae are from the Middle Eocene of China [7,8] while the most recent are from the latest Oligocene of Europe and Pakistan
This occurrence is related to a major extinction-origination event called the “Grande Coupure” [17], which roughly happens during the Eocene-Oligocene transition (34 Ma; [18])
Summary
Amynodontidae is an extinct family of Perissodactyla that is generally included in the Rhinocerotoidea (e.g. [1–4]). Amynodontidae is an extinct family of Perissodactyla that is generally included in the Rhinocerotoidea The oldest representatives of the family Amynodontidae are from the Middle Eocene of China [7,8] while the most recent are from the latest Oligocene of Europe and Pakistan (and not Early Miocene as previously suggested; [9,10]). Only the genus Cadurcotherium is recorded in Western Europe, during the Early Oligocene [13–16]. This occurrence is related to a major extinction-origination event called the “Grande Coupure” [17], which roughly happens during the Eocene-Oligocene transition (34 Ma; [18])
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