Dromomerycidae is an extinct family of

Neogene The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...

ruminants Ruminants are herbivorous grazing or browsing artiodactyls belonging to the suborder Ruminantia that are able to acquire nutrients from plant-based food by Enteric fermentation, fermenting it in a specialized stomach prior to digestion, principa ...

belonging to the infraorder

Pecora Pecora is an Order (biology), infraorder of Artiodactyla, even-toed hoofed mammals with ruminant digestion. Most members of Pecora have cranial appendages projecting from their frontal bones; only two extant genera lack them, ''Hydropotes'' and ...

. Dromomerycids, known by two subfamilies, were endemic to North America from the later early Miocene up to the early Pliocene (~5 Ma), leaving no descendants. Dromomerycidae has a long history of uncertain taxonomic affiliations due to its superficial resemblances with the Eurasian Neogene

Palaeomerycidae The Palaeomerycidae is an extinct family of Neogene ruminants belonging to the infraorder Pecora. Palaeomerycids lived in Europe and Asia exclusively during the Miocene, coevolving with cervids, bovids, moschids, and tragulids there as part o ...

and were traditionally classified as subfamilies within the family. However, recent research differentiates the dromomerycids from the Giraffomorpha ( Giraffoidea and Palaeomerycoidea) by the lack of sutures on the skull roof that typically make up the

ossicone Ossicones are columnar or conical skin-covered bone structures on the heads of giraffes, male okapi, and some of their extinct relatives. Ossicones are distinguished from the superficially similar structures of Horn (anatomy), horns and antlers ...

s of the later clade. The similar resemblances of the appendages therefore could be the result of

parallel evolution Parallel evolution is the similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure.Zhang, J. and Kumar, S. 1997Detection of convergent and pa ...

. Dromomerycids are characterized by unbranched and nondeciduous appendages above the orbits of the eyes. These traits may have been typically characteristic of males but appear to have been present in both sexes of '' Aletomeryx''. Little is known about them, however, since they very rarely are studied in the paleontological record. Dromomerycids may have been dense woodland and open bushlands/grasslands dwellers that mainly browsed on non-grass vegetation. Their gradual decline seems to have been the result of disappearances of suitable habitats as a result of increasing aridity and cooling climates.

Classification

* Dromomerycinae ** Dromomerycini *** '' Dromomeryx'' *** '' Rakomeryx'' *** '' Drepanomeryx'' ** Cranioceratini *** '' Cranioceras'' *** '' Barbouromeryx'' *** '' Bouromeryx'' *** '' Procranioceras'' *** '' Pediomeryx'' * Aletomerycinae ** '' Aletomeryx'' ** '' Sinclairomeryx'' ** '' Surameryx''

References

External links

{{Taxonbar, from=Q21291084 Miocene first appearances Pliocene extinctions Prehistoric mammal families Pecora Prehistoric Artiodactyla of North America