''Diegoaelurus'' ("San Diego's cat") 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 placental mammals from the extinct subfamily Machaeroidinae within extinct family Oxyaenidae. This genus contains only one species ''Diegoaelurus vanvalkenburghae'', which was found in the Santiago Formation in

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. This mammal lived during the Uintan stage of the Middle Eocene Epoch around 46.2 to 39.7 million years ago.

Etymology

The name of genus ''Diegoaelurus'' comes from city

San Diego San Diego ( , ) is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. With a population of over 1.4 million, it is the List of United States cities by population, eighth-most populous city in t ...

and . ''Diegoaelurus vanvalkenburghae'' was named after Dr. Blaire Van Valkenburgh in honor of her research on carnivorous mammals and saber-toothed predator paleoecology.

Discovery

The holotype fossils were discovered in Oceanside, San Diego county by paleontologist Brad Riney in 1988. The fossils were housed for over three decades in a

museum A museum is an institution dedicated to displaying or Preservation (library and archive), preserving culturally or scientifically significant objects. Many museums have exhibitions of these objects on public display, and some have private colle ...

until 2022 when the fossils were described and recognised as a new genus and species. This creature is so far the only

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 ...

n species of Machaeroidinae known outside of

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

and

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

. According to a paper on the creature, ''The present study highlights how poorly documented the machaeroidine fossil record remains''.

Description

''Diegoaelurus vanvalkenburghae'' was small in stature, with a size comparable to a fossa. The holotype fossils (SDSNH 38343) consists of a

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

and well preserved dentition. Its discovery has made paleontologists question whether this group's extinction was caused due to the large faunal turnover at the end of the Eocene. This creature as well as its subfamily were some of the first predatory saber toothed mammals to have evolved, 30 million years before the Machairodontinae (saber-toothed cats) evolved in the

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

. Due to the lack of remains, there is questioning to these animals

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...

s. However, there are good remains from ''Machaeroides eothen'' which support a hypercarnivorous lifestyle for the group. ''D. vanvalkenburghae'' is actually the latest surviving member of its subfamily.

Classification

The phylogenetic relationships of genus ''Diegoaelurus'' are shown in the following cladogram:

Extinction

''Diegoaelurus'' along with all the members of its

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 ...

went extinct at the end of the Eocene. A supported theory is that these mammals went extinct during the Eocene-Oligocene extinction event; A large faunal turnover at the end of the epoch was probably caused by climate change, like the freezing of Antarctica disrupting

ocean current An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, sh ...

s and global temperature. Many of the primitive mammals like the Palaeotheriidae, Xiphodontidae, Dichobunidae and the Adapidae were replaced by more advanced mammals like the Rhinocerotidae (true rhinos), Castoridae ( beavers) Oreodonts, and other more advanced Artiodacytyls as well as the Erinaceids ( hedgehogs). It seems once the Oxyaenids went extinct their ecological nice was filled in by the Nimravids, a family of saber-toothed mammals that belonged to the group Feliformia.

References

{{Taxonbar, from=Q111251465 Fossil taxa described in 2022 Mammals described in 2022 Oxyaenidae Prehistoric placental genera