''Kenyasaurus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

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 basal

tangasaurid Tangasauridae is a family of diapsids. Specimens have been found that are of Late Permian to Early Triassic in age from the Sakamena Group of western Madagascar. They lived alongside other taxa present from the Sakamena Group, including temnos ...

known from the

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

Coast Province The Coast Province ( sw, Mkoa wa Pwani) of Kenya, along the Indian Ocean, was one of Kenya's eight provinces. It comprises the Indian Ocean coastal strip with the capital city at Mombasa and was inhabited by the Mijikenda and Swahili, among oth ...

, southeastern

Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

. It contains a single species, ''Kenyasaurus mariakaniensis''.

Discovery

''Kenyasaurus'' is known only from the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

specimen, KNM-MA1, a well preserved and partially complete

postcranial Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated s ...

skeleton A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...

, lacking much of the

neck The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...

pectoral girdle The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans it consists of the clavicle and scapula; in those species with three bones in the shoulder, it consists of t ...

and

forelimb A forelimb or front limb is one of the paired articulated appendages (limbs) attached on the cranial ( anterior) end of a terrestrial tetrapod vertebrate's torso. With reference to quadrupeds, the term foreleg or front leg is often used instead. ...

, which is hosted at the Kenya National Museum. It was found at the

Mariakani Mariakani is a town in Kenya lying on the boundary of Kaloleni and Kinango districts (formerly Kilifi and Kwale respectively) in the old Coast Province of Kenya, 36 kilometres northwest of the port city of Mombasa. Administration during colonial p ...

locality which is located 25

mile The mile, sometimes the international mile or statute mile to distinguish it from other miles, is a British imperial unit and United States customary unit of distance; both are based on the older English unit of length equal to 5,280 English ...

s from

Mombasa Mombasa ( ; ) is a coastal city in southeastern Kenya along the Indian Ocean. It was the first capital of the British East Africa, before Nairobi was elevated to capital city status. It now serves as the capital of Mombasa County. The town is ...

, southeastern

Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

. It was collected from the upper part of the

Maji ya Chumvi Maji ya Chumvi is a settlement in Kenya's Coast Province The Coast Province ( sw, Mkoa wa Pwani) of Kenya, along the Indian Ocean, was one of Kenya's eight provinces. It comprises the Indian Ocean coastal strip with the capital city at Mombasa ...

Beds ( Maji-Ya-Chumvi Formation). These beds form the lower part of the Middle Duruma Sandstone Series (Duruma Group) and on the basis of lithological similarities with beds in Tanzania and Madagascar were dated to the

Induan The Induan is the first age of the Early Triassic epoch in the geologic timescale, or the lowest stage of the Lower Triassic series in chronostratigraphy. It spans the time between 251.902 Ma and Ma (million years ago). The Induan is sometimes ...

and

Olenekian In the geologic timescale, the Olenekian is an age in the Early Triassic epoch; in chronostratigraphy, it is a stage in the Lower Triassic series. It spans the time between Ma and Ma (million years ago). The Olenekian is sometimes divided i ...

stages of the

period, about 251.0-245

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

. This specimen represents the only reptilian fossils currently known from these beds.

Description

''Kenyasaurus'' is a relatively small, lightly built, general lizard-like form. In ''Kenyasaurus'' original description, Harris and Carroll (1977) assigned it to the "

Eosuchia Eosuchians are an extinct order of diapsid reptiles. Depending on which taxa are included the order may have ranged from the late Carboniferous to the Eocene but the consensus is that eosuchians are confined to the Permian and Triassic. Eosuch ...

" (a defunct clade that used to unit all diapsids more advanced than ''

Araeoscelis ''Araeoscelis'' (from el, αραιά , 'thin' and el, σκελίς , 'ribs of beef') is an extinction, extinct genus of reptile, and one of the earliest diapsids. Fossils have been found in the Nocona Formation, Nocona, Arroyo Formation, Arroyo ...

'') on the basis of its well developed

sternum The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...

and that the fifth distal tarsal is not a separate element, but the fifth

metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the med ...

is not hooked. It was considered to be most closely related to the aquatic eosuchians ''

Tangasaurus ''Tangasaurus'' is an extinct genus of aquatic basal tangasaurid neodiapsid known from the Late Permian period (late Changhsingian stage) of Tanga, northeastern Tanzania. It contains a single species, ''Tangasaurus mennelli''. Discovery ''Ta ...

'' and ''

Hovasaurus ''Hovasaurus'' is an extinct genus of diapsid reptile belonging to the order Eosuchia. It lived in what is now Madagascar during the Late Permian and Early Triassic, being a survivor of the Permian–Triassic extinction event and the paleontologi ...

'' (from

Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...

and

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

) based on its small size and general body proportions. Harris and Carroll noted that its tail is not specialized as a swimming organ as it is in

Philip J. Currie Philip John Currie (born March 13, 1949) is a Canadian palaeontologist and museum curator who helped found the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta and is now a professor at the University of Alberta in Edmonton. In the ...

(1982) redescribed ''Tangasaurus'' and its relationships with other "eosuchians". He diagnosed ''Kenyasaurus'' on the basis of five

autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

: It possesses low but anteroposteriorly elongate

neural spine The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

s in the dorsal region, 56

caudal vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

and 28 pairs of caudal ribs and transverse processes. Its

astragalus ''Astragalus'' is a large genus of over 3,000 species of herbs and small shrubs, belonging to the legume family Fabaceae and the subfamily Faboideae. It is the largest genus of plants in terms of described species. The genus is native to tempe ...

is almost triangular rather than primitive L-shape and it has pronounced process on fifth metatarsal for insertion of peroneus brevis. Currie (1982) united two subfamilies within the Tangasauridae: Kenyasaurinae (that he named to include ''Kenyasaurus'' and ''

Thadeosaurus ''Thadeosaurus'' is an extinct genus of diapsid reptile belonging to the family Younginidae. Fossils have been found in the Lower Sakamena Formation ( Sakamena Group) of the Morondava Basin, Madagascar in 1981, and date to the late Permian to ...

'', both are thought to be terrestrial) and Tangasaurinae (to include the aquatic ''Tangasaurus'' and ''Hovasaurus''). He allied Tangasauridae and ''Youngina'' together within superfamily Younginoidea which he named. Currie (1980) named ''

Acerosodontosaurus ''Acerosodontosaurus'' is an extinct genus of neodiapsid reptiles that lived during the Upper Permian of Madagascar. The only species of ''Acerosodontosaurus'', ''A. piveteaui'', is known from a natural mold of a single partial skeleton including ...

'', and allied it with Younginoidea in the clade

Younginiformes Younginiformes is a replacement name for the taxon Eosuchia, proposed by Alfred Romer in 1947. The Eosuchia having become a wastebasket taxon for many probably distantly-related primitive diapsid reptiles ranging from the late Carboniferous to ...

. Currie's (1982) classification of the Younginiformes had been accepted by many scientists before they could perform large and computerized analyses. More recent works that use

phylogenetic 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 ...

analyses usually suggest that neither Younginoidea nor Younginiformes are

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

. Constanze Bickelmann, Johannes Müller and Robert R. Reisz (2009) redescribed ''Acerosodontosaurus'' and suggested an aquatic lifestyle for it. Their analysis is figured below, and it found support for two distinct families within "Younginiformes": the aquatic Tangasauridae, and the terrestrial Younginidae (in partial

polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...

with Tangasauridae). However, they found no support for the inclusion of ''Kenyasaurus'' within any of those families. More resolved results were obtained by Reisz ''et al.'' (2011) in their description of ''

Orovenator ''Orovenator'' is an extinct genus of diapsid from Lower Permian (Artinskian stage) deposits of Oklahoma, United States. It is known from two partial skulls from the Richards Spur locality in Oklahoma. The holotype OMNH 74606 consists of a p ...

''. However, those results required the exclusion of the fragmentary taxa '' Galesphyrus'', ''Kenyasaurus'', '' Palaeagama'' and ''

Saurosternon ''Saurosternon'' is an extinct genus of neodiapsid reptile from the Late Permian of South Africa. It is based on a partial skeleton split between two slabs of sandstone from the ''Daptocephalus'' Assemblage Zone. ''Saurosternon'' was one of th ...

'' from their analysis.

Etymology

''Kenyasaurus'' was first described and named by John M. Harris and

Robert L. Carroll Robert "Bob" Lynn Carroll (May 5, 1938 – April 8, 2020) was an American–Canadian vertebrate paleontologist who specialised in Paleozoic and Mesozoic amphibians and reptiles. Biography Carroll was an only child and grew up on a farm ne ...

in 1977 and 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 ...

is ''Kenyasaurus mariakaniensis''. The generic name is derived from the name of the

Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

in which the only known specimen was found, and

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''sauros'', meaning "lizard". The specific name is derived from the name of the type locality of the genus,

References

{{Taxonbar, from=Q2908528 Fossil taxa described in 1977 Triassic diapsids Early Triassic reptiles of Africa Prehistoric reptile genera