Leptomerycinae 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 botanical subfamily names with "-oideae", and zo ...

within the

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

family Leptomerycidae. It contains four genera, ''

Leptomeryx ''Leptomeryx'' is an extinct genus of ruminant of the family Leptomerycidae, endemic to North America during the Eocene through Oligocene 38–24.8 Mya, existing for approximately . It was a small deer-like ruminant with somewhat slender body. ...

'', ''Pronodens'', ''Pseudoparablastomeryx,'' and ''Santuccimeryx'', which lived in North America during the

Middle Eocene The Eocene ( ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', ' Dawn') a ...

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene epoch (geology), epoch made up of two Stage (stratigraphy), stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0. ...

. The Leptomerycinae were primitive and ancient ruminants, resembling small

deer A deer (: deer) or true deer is a hoofed ruminant ungulate of the family Cervidae (informally the deer family). Cervidae is divided into subfamilies Cervinae (which includes, among others, muntjac, elk (wapiti), red deer, and fallow deer) ...

musk deer Musk deer can refer to any one, or all eight, of the species that make up ''Moschus'', the only extant genus of the family (biology), family Moschidae. Despite being commonly called deer, they are not true deer belonging to the family Cervidae, b ...

, or

chevrotain Chevrotains, or mouse-deer, are small, even-toed ungulates that make up the family Tragulidae, and are the only living members of the infraorder Tragulina. The 10 extant species are placed in three genera, but several species also ar ...

s. The first skull attributed to the genus ''Santuccimeryx,'' described as a potential link between ''Leptomeryx'' and ''Pseudoparablastomeryx,'' was discovered at

Badlands National Park Badlands National Park () is a List of national parks of the United States, national park of the United States in southwestern South Dakota. The park protects of sharply Erosion, eroded buttes and Pinnacle (geology), pinnacles, along with the l ...

in 2016 by a park intern. The skull, initially assigned to ''Leptomeryx elissae,'' was collected from the park's Oligocene-age

Brule Formation The Brule Formation was deposited between 34 and 30 million years ago, roughly the Rupelian age (Oligocene). It occurs as a subunit of the White River Group in South Dakota, Nebraska, Colorado, North Dakota, and Wyoming. It is a sequence of fin ...

and is the most complete specimen of ''Leptomeryx elissae'' known to date. The presence of both dentary and skull material revealed significant differences from the ''Leptomeryx'' genus however, which prompted the taxonomical overhaul of the subfamily and led to ''L. elissae'' being reclassified into a new genus: ''Santuccimeryx elissae.''

References

{{Taxonbar, from=Q6528179 Eocene Artiodactyla Miocene Artiodactyla Oligocene Artiodactyla Miocene extinctions Prehistoric mammals of North America Eocene first appearances