''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 extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of early

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

(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 com ...

) from the

Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...

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 Haramiyida ("thief" from Arabic الحرامية (al ḥarāmiyah), "thief, bandit") is a possibly polyphyletic order of mammaliaform cynodonts or mammals of controversial taxonomic affinites. Their teeth, which are by far the most common remains ...

. 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 specimen ...

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

Nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, 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. ...

'' 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 (anatomy), organ that has Adaptation (biology), adapted for grasping or holding. The word is derived from the Latin term ''prehendere'', meaning "to grasp". The ability to grasp is likely der ...

, 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 Animal body, body part that assists an animal in obtaining lift (force), lift when gliding flight, gliding or flight. The structure is found in extant taxon, extant and extinct groups of flying and g ...

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 tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

, 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, wh ...

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 A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

or evolutionary grouping called Mammaliaformes, which includes mammals and their closest extinct relatives from the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

and

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), 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 J ...

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 In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

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 d ...

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