''Arboroharamiya'' ("tree thief" from Latin arbor, "tree" + Arabic الحرامية (al ḥarāmiyah), "thief, '' Haramiya''") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of early mammal (or possibly a non-mammalian

mammaliaform Mammaliaformes ("mammalian forms") is a clade that contains the crown group mammals and their closest extinct relatives; the group radiated from earlier probainognathian cynodonts. It is defined as the clade originating from the most recent comm ...

) from the Middle Jurassic

Tiaojishan Formation The Tiaojishan Formation is a geological formation in Hebei and Liaoning, People's Republic of China, dating to the middle-late Jurassic period (Bathonian- Oxfordian stages). It is known for its exceptionally preserved fossils, including those of ...

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for a ...

, China. ''Arboroharamiya'' belongs to a group of mammaliaforms called Haramiyida. The

type species In 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 species that contains the biological type specime ...

''Arboroharamiya jenkinsi'' was described in the journal ''

Nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...

'' in 2013 alongside a description of the closely related haramiyidan ''

Megaconus ''Megaconus'' is an extinct genus of allotherian mammal from the Middle Jurassic Tiaojishan Formation of Inner Mongolia, China. The type and only species, ''Megaconus mammaliaformis'' was first described in the journal ''Nature'' in 2013. ''Meg ...

''. Unlike ''Megaconus'', which is thought to have been ground-dwelling, ''Arboroharamiya'' was arboreal. It has a long tail that might have been

prehensile Prehensility is the quality of an appendage or organ that has adapted for grasping or holding. The word is derived from the Latin term ''prehendere'', meaning "to grasp". The ability to grasp is likely derived from a number of different orig ...

, and very long fingers. Based on the shape of its teeth, ''Arboroharamiya'' might have been an omnivore or a seed eater. Recent interpretations of its specimen suggest that it possessed

patagia The patagium (plural: patagia) is a membranous body part that assists an animal in obtaining lift when gliding or flight. The structure is found in extant and extinct groups of flying and gliding animals including bats, birds, some dromaeosau ...

and was a glider. When ''Arboroharamiya'' was included in a

phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

of early mammals and mammaliaforms, Haramiyida was found to be a group within Mammalia, the true mammals. However, ''Megaconus'' was included in a different phylogenetic analysis, and that analysis placed Haramiyida outside Mammalia as a more basal ("primitive") group of mammaliaforms. The classification of ''Arboroharamiya'' and other haramiyidans as true mammals fits with what most previous studies have found, but since ''Arboroharamiya'' and ''Megaconus'' were not included in the same phylogenetic analysis, their position within Mammaliaformes remains uncertain.

Description

''Arboroharamiya'' is the largest known haramiyidan, estimated to have weighed about 354 g. It has several features in common with living mammals, including a lower jaw formed by a single bone, the

dentary In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

, and hands and feet that each have four fingers with three bones each and one finger with two bones. ''Arboroharamiya'' is unlike any modern mammal in having a lower jaw that can move up, down, and backward, but not forward. It has a rodent-like dentition with enlarged

incisors Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

and

molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

and no

canines Canine may refer to: Zoology and anatomy * a dog-like Canid animal in the subfamily Caninae ** ''Canis'', a genus including dogs, wolves, coyotes, and jackals ** Dog, the domestic dog * Canine tooth, in mammalian oral anatomy People with the surn ...

. A rodent-like dentition is also seen in

Multituberculata 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 ...

, an early group of mammals that might be closely related to ''Arboroharamiya'', but it probably evolved independently in ''Arboroharamiya''.

Relationships

''Arboroharamiya'' belongs to a clade or evolutionary grouping called Mammaliaformes, which includes mammals and their closest extinct relatives from the

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

and

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

periods. Within Mammaliaformes, ''Arboroharamiya'' falls within the clade Haramiyida. Haramiyidans have been known since the 1840s, but only from fossilized teeth and a single partial lower jaw. However, several features of the teeth have shown for many years that haramiyidans are among the most basal of mammaliaforms. Recent phylogenetic analyses, or analyses of evolutionary relationships, differ on whether or not haramiyidans are true mammals in the crown group Mammalia (the clade including the

most recent common ancestor In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The ...

of living mammals, and all its descendants). Some analyses place Haramiyida outside crown group Mammalia, meaning that they diverged from other mammaliaforms before the most recent common ancestor of living mammals appeared. Other analyses place Haramiyida within Mammalia as part of an extinct group of Mesozoic mammals called

Allotheria Allotheria (meaning "other beasts", from the Greek , '–other and , '–wild animal) is an extinct branch of successful Mesozoic mammals. The most important characteristic was the presence of lower molariform teeth equipped with two longitudin ...

, which also includes Multituberculata. When ''Arboroharamiya'' itself was incorporated into a phylogenetic analysis, Haramiyida fell within Allotheria as a group within Mammalia. Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

or evolutionary tree from the analysis:

References

{{Taxonbar, from=Q14611019 Fossil taxa described in 2013 Middle Jurassic synapsids of Asia Euharamiyids Prehistoric cynodont genera Paleontology in Inner Mongolia Taxa named by Xiaoting Zheng Taxa named by Shundong Bi Taxa named by Xiaoli Wang (paleontologist) Taxa named by Jin Meng