Thaumastocyoninae is an extinct

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

of amphicyonids, large terrestrial carnivores, which inhabited what is now Europe during the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

epoch. The subfamily was erected by Hürzeler (1940), and is defined by the complete suppression of m1 metaconid, reduction of the

premolar The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...

s, except the p4, which is reinforced, and the oblique abrasion of the teeth, and the possession of

hypercarnivorous A hypercarnivore is an animal which has a diet that is more than 70% meat, either via active predation or by scavenging. The remaining non-meat diet may consist of non-animal foods such as fungi, fruits or other plant material. Some extant exampl ...

tendencies. Thaumastocyonines are poorly known, with only about 65 dental specimens, most of those isolated teeth, being known as of 2020,Morlo M, Bastl K, Habersetzer J, Engel T, Lischewsky B, Lutz H, von Berg A, Rabenstein R, Nagel D. 2020
The apex of amphicyonid hypercarnivory: solving the riddle of ''Agnotherium antiquum'' Kaup, 1833 (Mammalia, Carnivora).
Journal of Vertebrate Paleontology 39(5):e1705848 DOI 10.1080/02724634.2019.1705848. although more complete remains have recently been discovered.

Evolution and phylogeny

The first thaumastocyonines appear during the earliest Miocene epoch in the form of ''Crassidia intermedia'', which was already the largest predator in its habitat. However, they diversified following the major faunal and climatic changes of the

Orleanian The Orleanian age is a period of geologic time ( MN 3–5, (mya)), within the Miocene and used more specifically with European Land Mammal Ages. It precedes the Astaracian age and follows the Agenian age. ; Agenian-Early Orleanian migration At ...

. The replacement of Western Europe's arid landscape with wet environments, combined with the dispersal of African and Asian

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

into Europe, lead to a reconstruction of the local faunal community. As a result, the Haplocyoninae disappeared from Europe, while their close relatives, the thaumastocyonines and amphicyonines, flourished. The Thaumastocyoninae reached their peak diversity during MN9 stage of the

Vallesian The Vallesian age is a period of geologic time (11.6–9.0 Ma) within the Miocene used more specifically with European Land Mammal Ages. It precedes the Turolian age and follows the Astaracian age. The so-called Vallesian Crisis resulted in the e ...

, but they disappeared soon after. One possible explanation are the effects of the Vallesian Crisis, a major local extinction event as a result of the reduction of forests in favor of open habitats, which reshaped Europe's fauna. Among thaumastocyonines, only ''Ammitocyon'' is known after this event. Below is a cladogram based on cranial, mandibular and dental characters, after Morales et al., 2021,Jorge Morales, Juan Abella, Oscar Sanisidro & Alberto Valenciano (2021
''Ammitocyon kainos'' gen. et sp. nov., a chimerical amphicyonid (Mammalia, Carnivora) from the late Miocene carnivore traps of Cerro de los Batallones (Madrid, Spain)
''Journal of Systematic Palaeontology'', 19:5, 393-415, DOI: 10.1080/14772019.2021.1910868 showing the phylogenetic relationships between the species of the subfamily:

Classification

References

{{Taxonbar, from=Q33147923 Fossil taxa described in 1940 Miocene Europe Prehistoric carnivorans of Europe Bear dogs Mammal subfamilies