''Diacodexis'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of small herbivorous mammals belonging to the family Diacodexeidae that lived in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

from 55.4 mya to 46.2 mya, existing for approximately .

Description

''Diacodexis'' is the oldest known even-toed ungulate. In life, it would have resembled a modern

duiker A duiker is a small to medium-sized brown antelope native to sub-Saharan Africa, found in heavily wooded areas. The 22 extant species, including three sometimes considered to be subspecies of the other species, form the subfamily Cephalophinae ...

, measuring about in body length, but with a much longer tail. Unlike most later species of artiodactyl, it still had five toes on each foot, although the third and fourth toes were already elongated. It may also have had small hooves on each toe. Its teeth suggest that it was a herbivorous browser. ''D. ilicis'' possessed a very simple

neocortex The neocortex, also called the neopallium, isocortex, or the six-layered cortex, is a set of layers of the mammalian cerebral cortex involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, ...

, characterised by an almond-shaped

gyrus In neuroanatomy, a gyrus (: gyri) is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci (depressions or furrows; : sulcus). Gyri and sulci create the folded appearance of the brain in humans and other mammals. ...

instead of parallel sulci as some earlier authors had believed. As suggested by its long legs, ''Diacodexis'' is believed to have been fast-running, capable of leaping relatively far.

Fossil distribution

''Diacodexis'' was widespread, with

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

having been found throughout Europe and North America. However, the genus is currently considered

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

, with the various species likely being a loose conglomerate of basal artiodactyls, rather than a natural grouping.Rautela, A., & Bajpai, S. (2023). Gujaratia indica, the oldest artiodactyl (Mammalia) from South Asia: new dental material and phylogenetic relationships. Journal of Systematic Palaeontology, 21(1). https://doi.org/10.1080/14772019.2023.2267553

References

Bibliography

* Dichobunids Eocene Artiodactyla Ypresian life Lutetian life Wasatchian Bridgerian Eocene mammals of Asia Paleogene India Fossils of India Fossils of Kyrgyzstan Fossils of Pakistan Eocene mammals of Europe Paleogene Belgium Fossils of Belgium Paleogene England Fossils of England Paleogene France Fossils of France Paleogene Portugal Fossils of Portugal Paleogene Spain Fossils of Spain Eocene mammals of North America Fossils of the United States Paleontology in Colorado Paleontology in Mississippi Paleontology in New Mexico Paleontology in North Dakota Paleontology in Wyoming Fossil taxa described in 1882 Taxa named by Edward Drinker Cope Prehistoric Artiodactyla genera {{paleo-eventoedungulate-stub