''Lambdopsalis'' is an extinct

multituberculate Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, a ...

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

from the Late

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

and Mongolia. It is placed within the suborder

Cimolodonta Cimolodonta is a clade of Multituberculata, multituberculate mammals that lived from the Cretaceous to the Eocene. They probably lived something of a rodent-like existence until their ecological niche was assumed by true rodents. The more basal ...

and is a member of the superfamily

Taeniolabidoidea Taeniolabidoidea is a group of extinct mammals known whose fossils can be found in North America and Asia. They were the largest members of the extinct order Multituberculata, as well as the largest non-therian mammals. '' Lambdopsalis'' even pr ...

Fossil 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 preserve ...

remains have been found in the Late Paleocene Nomogen and Khashat Formations in Nao-mugen and Bayn Ulan of China and Mongolia, dated to 59-55 million years ago from the

Thanetian The Thanetian is, in the International Commission on Stratigraphy, ICS Geologic timescale, the latest age (geology), age or uppermost stage (stratigraphy), stratigraphic stage of the Paleocene epoch (geology), Epoch or series (stratigraphy), Serie ...

age. ''Lambdopsalis bulla'' is the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of this genus. The genus and species were named by Chow and Tao Qi in 1978. Hair and fur fossilize very infrequently, if at all. This genus of multituberculate mammals provides one of the earliest unequivocal examples of mammal fur (Lower

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

fossils of '' Eomaia, Volaticotherium'' and ''

Castorocauda ''Castorocauda'' is an extinct, semi-aquatic, superficially otter-like genus of docodont mammaliaforms with one species, ''C. lutrasimilis''. It is part of the Yanliao Biota, found in the Daohugou Beds of Inner Mongolia, China dating to the ...

'' with the fur preserved still attached are currently the oldest). Indirect evidence suggest that hair first appeared on non-mammalian therapsids (

Therapsida Therapsida is a clade comprising a major group of eupelycosaurian synapsids that includes mammals and their ancestors and close relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including l ...

), back in the

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

or even earlier. This is inferred from small hollows on the bone of the snout similar to holes in the skulls of cats which provide space for concentrations of

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...

s and

blood vessel Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...

s that innervate prominent whiskers (specialized hairs). This adaptation allows cats to use their whiskers as effective tactile sensory organs. In the same Upper Paleocene strata, exceptionally preserved

coprolite A coprolite (also known as a coprolith) is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. The name ...

s, originally excreted by unknown carnivorous animals, were discovered to contain undigested remains, including hair from ''Lambdopsalis'' and three other different mammal taxa. Studies on its tooth prism and enamel patterns have been performed. It had deciduous enamel, and there is evidence that adults and juveniles had substantially different diets.

Cervical vertebrae In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In saurop ...

C2-C3 or C2-C3-C4 appear to be typically fused in individuals of this genus. Based on its robust

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

bones, its flat skull, its fused and stiff neck bones, and thick enamel on its lower incisors, it is believed that this genus was either partially or fully adapted to a burrowing (

fossorial A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...

) lifestyle. Kielan-Jaworowska and Qi suggest similar locomotive behavior to the modern Golden mole. Fully grown ''L.bulla'' individuals were estimated to have had a body mass of and skull length of about .Wilson et al 2012, Supplemental Table 5

Notes

References

* * * * * * * * {{Taxonbar, from=Q1419682 Cimolodonta Paleocene mammals of Asia Paleocene genus extinctions Prehistoric animals of China Fossils of Mongolia Fossil taxa described in 1978 Prehistoric mammal genera