''Oxlestes'' is an extinct mammal from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

, more specifically from the

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

Uzbekistan , image_flag = Flag of Uzbekistan.svg , image_coat = Emblem of Uzbekistan.svg , symbol_type = Emblem of Uzbekistan, Emblem , national_anthem = "State Anthem of Uzbekistan, State Anthem of the Republ ...

. A

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

species of uncertain affinities, it is notable for its relatively large size, being among the largest of all Mesozoic mammals.L. A. Nessov. 1982. Drevneishie mlekopitaiushchie SSSR ncient mammals of the USSR Palyentologicheskogo Obshchyestva 25:228-243 Due to the limited amount of material, it has been considered a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium,'' it may be impossible to determine whether a ...

''.

Description

''Oxlestes'' is currently a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus, containing a single species, ''O. grandis''. Its specimens were recovered in the

-aged Khodzhakul Formation of

. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

, CCMGE 6/11758, is composed of an

axis An axis (: axes) may refer to: Mathematics *A specific line (often a directed line) that plays an important role in some contexts. In particular: ** Coordinate axis of a coordinate system *** ''x''-axis, ''y''-axis, ''z''-axis, common names ...

vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

, dentaries,

canine Canine may refer to: Zoology and anatomy * Animals of the family Canidae, more specifically the subfamily Caninae, which includes dogs, wolves, foxes, jackals and coyotes ** ''Canis'', a genus that includes dogs, wolves, coyotes, and jackals ** Do ...

teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

and a

sagittal crest A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are excepti ...

. The axis is relatively narrow, with a long, pointed anterior process. There are two pairs of distinct

foramina In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, arter ...

anterior and posterior to the dorsal transverse suture; modern

placentals Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguishe ...

only bear one. It is about 1.9 centimeters long. The dentaries are short and robust, with a convex central border. The

masseter In anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it is the ...

ic fossa is deep, and the canine is long and deep. The skull has been suggested to be about 10 centimeters long; one axis and dentary comparison to zhelestids and

rabbits Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated form ...

would make it somewhat smaller at 7.5 centimeters, though this has since been contested. Overall, the available proportions seem to indicate an animal comparable in size to the largest of modern

mustelids The Mustelidae (; from Latin , weasel) are a diverse family of carnivoran mammals, including weasels, badgers, otters, polecats, martens, grisons, and wolverines. Otherwise known as mustelids (), they form the largest family in the suborder Can ...

and mid-sized

felines Feline may refer to: Zoology * Loosely, Felidae, a member of the cat family, which includes the subfamilies Pantherinae and Felinae (conventionally designated a felid). ** Following the taxonomic convention, Felinae, the subfamily of Felidae that ...

Classification

''Oxlestes'' was initially referred to

Palaeoryctidae Palaeoryctidae ("ancient diggers") is an extinct family of non-specialized eutherian mammals from extinct order Palaeoryctida, that lived in North America, Europe, Asia and Africa from the late Cretaceous to the middle Eocene.Gregg F. Gunnell, Th ...

, a

eutheria Eutheria (from Greek , 'good, right' and , 'beast'; ), also called Pan-Placentalia, is the clade consisting of Placentalia, placental mammals and all therian mammals that are more closely related to placentals than to marsupials. Eutherians ...

n family, based on comparisons with several other Cretaceous eutherians like ''

Zalambdalestes ''Zalambdalestes'' (meaning ''much-like-lambda robber'') is an extinct genus of eutherian mammal known from the Upper Cretaceous in Mongolia. Description ''Zalambdalestes'' was a hopping animal with a long snout, long teeth, a small brain and ...

'', '' Barunlestes'' and '' Asioryctes'' (none of which considered to be palaeoryctids anymore; Palaeoryctidae as a whole may be invalid). Posterior efforts have cautiously referred it to the

metatheria Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as wel ...

n clade

Deltatheroida Deltatheroida is an extinct group of basal metatherians that were distantly related to modern marsupials. The majority of known members of the group lived in the Cretaceous; one species, '' Gurbanodelta kara'', is known from the late Paleocene ( ...

, mostly based on size and its carnivorous speciations, but recent studies have shown no evidence of specifically deltatheroidean or even metatherian characters. Averinov and Archibald et al. 2005 referred it to the eutherian clade Zhelestidae, suggesting a close relation to '' Sheikhdzheilia'' though this too is not entirely certain.J. DAVID ARCHIBALD and ALEXANDER AVERIANOV, Phylogenetic analysis, taxonomic revision, and dental ontogeny of the Cretaceous Zhelestidae (Mammalia: Eutheria), Version of Record online: 25 JAN 2012

Ecology

''Oxlestes'' was among the largest mammals of the Mesozoic, being comparable in size to modern mammalian predators such as

wolverines The wolverine ( , ; ''Gulo gulo''), also called the carcajou or quickhatch (from East Cree, ''kwiihkwahaacheew''), is the largest land-dwelling member of the family Mustelidae. It is a muscular carnivore and a solitary animal. The wolverine ...

and mid-sized

cats The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...

. Its deep sagittal crest and masseteric fossae are indicative of powerful jaw musculature, and it possessed deep canines, both characteristics of predatory mammals. Some of these are shared with the contemporary deltatheroidean mammals, to which it could be related. If ''Oxlestes'' was a zhelestid, it would set a precedent in an otherwise herbivorous clade.Michael J. Benton, Mikhail A. Shishkin, David M. Unwin, The Age of Dinosaurs in Russia and Mongolia, Cambridge University Press, 04/12/2003 - 740 páginas It is larger than some contemporary

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

species. Some researchers have even suggested that it could have predated on the local small

ceratopsia Ceratopsia or Ceratopia ( or ; Ancient Greek, Greek: "horned faces") is a group of herbivore, herbivorous, beaked dinosaurs that thrived in what are now North America, Asia and Europe, during the Cretaceous Period (geology), Period, although ance ...

ns such as ''

Asiaceratops ''Asiaceratops'' (meaning "Asian horned face") is a genus of herbivorous ceratopsian dinosaur. It lived during the Early-Late Cretaceous. The type species, ''A. salsopaludalis'' is known from Uzbekistan, while ''A. sulcidens'' is known from Chin ...

''.

References

{{Taxonbar, from=Q24883317 Cretaceous animals of Asia Prehistoric eutherians Cretaceous mammals Late Cretaceous mammals of Asia Fossil taxa described in 1982 Prehistoric mammal genera