''Rajouria'', named after the

Rajouri district Rajouri is a district in the Jammu division of Indian union territory of Jammu and Kashmir (union territory), Jammu and Kashmir, in the larger Kashmir#Dispute, disputed Kashmir region. The application of the term "administered" to the various re ...

in the

Indian Indian or Indians may refer to: Associated with India * of or related to India ** Indian people ** Indian diaspora ** Languages of India ** Indian English, a dialect of the English language ** Indian cuisine Associated with indigenous peoples o ...

province of

Jammu and Kashmir Jammu and Kashmir may refer to: * Jammu and Kashmir (union territory), a region administered by India as a union territory since 2019 * Jammu and Kashmir (state), a region administered by India as a state from 1952 to 2019 * Jammu and Kashmir (prin ...

, 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 ...

raoellid

artiodactyl Artiodactyls are placental mammals belonging to the order Artiodactyla ( , ). Typically, they are ungulates which bear weight equally on two (an even number) of their five toes (the third and fourth, often in the form of a hoof). The other t ...

from the middle-upper

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

(early

Lutetian The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it ...

). There is only a single species of ''Rajouria'', ''Rajouria gunnelli'', which is named after Dr. Greg Gunnell. ''Rajouria'' is known from relatively little remains, with only

mandibular 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 maxillary fragments with their respective

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 ...

being preserved.

Discovery

''Rajouria'' was discovered near the town of Aiji in the East-Aiji 2 locality. The initial remains of ''Rajouria'' were all found in proximity to each other and are the only remains assigned to ''Rajouria''.

Classification

When it was first discovered, ''Rajouria'' was placed within Raoellidae. Its position as a raoellid has remained stable, although it is not certain where exactly it is within Raoellidae. In the

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

of Raoellidae by Rana et al., ''Rajouria'' was placed as the most basal raoellid due to the presence of the paracone on lower

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

and a relatively simple fourth

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

. However, Weppe et al. noted that, similar to ''

Metkatius ''Metkatius'', named after the town of Metka in the province Jammu and Kashmir, is a small extinct raoellid artiodactyl which inhabited northern India during the Middle Eocene (48-45 Mya) during the Early Lutetian age. Metkatius is known from fr ...

, Rajouria'' possessed somewhat lophodont molars that represented a transition in Raoellidae from the large lophs of ''

Indohyus ''Indohyus'' (Meaning "India's pig" from the Greek words ''Indos'', "from India" and ''hûs'', "pig") is an extinct genus of artiodactyl known from Eocene fossils in Asia. This small chevrotain-like animal found in the Himalayas is among the clo ...

'' and '' Kunmunella'' to the extreme bunodonty of ''Khirtharia''. Therefore ''Rajouria'' could also be an intermediate raoellid instead of the most basal member.

Description

''Rajouria'' is an average-sized raoellid with teeth similar to ''Indohyus'' and ''Kunmunella'' although slightly more bunodont.

Upper dentition

There are many fine grooves on all of the teeth. While the second premolar is still erupting, it was tall, sharp, and single cusped; it would have appeared very similar to a

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 ...

. The third premolar was double-rooted and compressed sideways. The fourth premolar is triple rooted with complete cingulum. The paracone is very large while the protocone, separated from the paracone by a deep ridge, is very small and positioned slightly forward of the paracone. The first molar is triple-rooted, similar to the fourth premolar. However, it is different in that it is subrectangular, larger, and has a L/W ratio approaching 1. It has four main cusps. The protocone is the largest cusp, followed by the paracone and then the metacone. The second molar is similar in looks to the first molar, although it is much larger. The third molar is about the same size as the second although it is much less rectangular. It is roughly trapezoidal in shape, with the anterior portion of the tooth being the widest. The metacone is shifted lingually (tongue side). The protocone is larger than in the first molar.

Lower dentition

The second and third premolar are similar in morphology. Neither have a parastylid or a distosytlid. Cingulum is small but continuous, being most prominent in the front and aft sections of the teeth. The fourth premolar is the longest and widest of the premolars. There is no metaconid. There is a small but relatively deep talonid basin. The size of molars increases dramatically and sequentially, with the first molar being the smallest. The cuspids are bunodont but high. The molars are double-rooted. The first molar is much longer than it is wide and trapezoidal, with its width increasing posteriorly. The metaconid is the highest cusp while the paraconid and protoconid are small. The second molar is similar, although it is larger and more rectangular and the trigonid basin is larger than the talonid basin. The third molar is similar to the second molar although it is larger and has more bulbous cusps. The metaconid is slightly more lingual than the entoconid and the protoconid is slightly more labial than the hypoconid. Similar to the second molar, the trigonid basin is larger than the talonid basin. Lingual cingulid is absent.

Dentary

The

dentary 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 ...

is narrow anteriorly and slightly wider posteriorly.

Mandibular symphysis In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral ha ...

stops only at the second premolar. There are two

mental foramina The mental foramen is one of two foramina (openings) located on the anterior surface of the mandible. It is part of the mandibular canal. It transmits the terminal branches of the inferior alveolar nerve and the mental vessels. Structure The ...

under the first and third premolars respectively.

Paleobiology

Due to the nature of its teeth, ''Rajouria'' was an average raoellid in terms of its diet. It would have most likely been primarily

herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

, but opportunistically hunt small animals (like

rodents Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

). The caniniform second (and likely first) premolars indicate that ''Rajouria'' grasped and held onto prey with its front teeth, which is an adaptation for

carnivory 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 ...

, but the last two premolars and the molars with somewhat prominent lophs point to a herbivorous lifestyle. Since ''Rajouria'' was a raoellid, it would have been semi-aquatic, similar to a chevrotain.

References

{{Taxonbar, from=Q134562493 Whippomorphs Prehistoric Artiodactyla genera Fossil taxa described in 2021 Eocene Artiodactyla Eocene mammals of Asia