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''Asperoris'' 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 n ...
of
archosauriform Archosauriformes (Greek for 'ruling lizards', and Latin for 'form') is a clade of diapsid reptiles that developed from archosauromorph ancestors some time in the Latest Permian (roughly 252 million years ago). It was defined by Jacques Gauthie ...
reptile known from the
Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma ...
Manda Beds The Manda Formation (also known as the Manda Beds) is a Middle Triassic (Anisian?) or possibly Late Triassic (Carnian?) geologic formation in Tanzania. It preserves fossils of many terrestrial vertebrates from the Triassic, including some of the e ...
of southwestern
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 ...
. It is the first archosauriform known from the Manda Beds that is not an
archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avi ...
. However, its relationships with other non-archosaurian archosauriforms are uncertain. It was first named by Sterling J. Nesbitt, Richard J. Butler and David J. Gower in
2013 File:2013 Events Collage V2.png, From left, clockwise: Edward Snowden becomes internationally famous for leaking classified NSA wiretapping information; Typhoon Haiyan kills over 6,000 in the Philippines and Southeast Asia; The Dhaka garment ...
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 ''Asperoris mnyama''. ''Asperoris'' means "rough face" in
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
, referring to the distinctive rough texture of its skull bones.


Discovery

''Asperoris'' is known solely from the well-preserved but incomplete
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 seve ...
skull NHMUK PV R36615, which includes the right
premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...
and
maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The ...
bones of the upper jaw, the right
nasal Nasal is an adjective referring to the nose, part of human or animal anatomy. It may also be shorthand for the following uses in combination: * With reference to the human nose: ** Nasal administration, a method of pharmaceutical drug delivery * ...
,
prefrontal Prefrontal may refer to: *Prefrontal bone, a skull bone in some tetrapods *Prefrontal cortex, a region of the brain of a mammal *Prefrontal scales The prefrontal scales on snakes and other reptiles are the scales connected to the frontals, toward ...
,
frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music *The Front (band), an American rock band signed to Columbia Records and active in the 1980s and ea ...
,
postfrontal The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
, and
parietal bone The parietal bones () are two bones in the skull which, when joined at a fibrous joint, form the sides and roof of the cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named ...
s of the top of the skull, and part of the right
postorbital bone The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some v ...
behind the eye socket, as well as three unidentified skull fragments. NHMUK PV R36615 was discovered by a joint 1963 expedition of the
Natural History Museum A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more ...
and the
University of London The University of London (UoL; abbreviated as Lond or more rarely Londin in post-nominals) is a federal public research university located in London, England, United Kingdom. The university was established by royal charter in 1836 as a degre ...
to eastern Zambia and western Tanzania (then northern Rhodesia and Tanganyika, respectively). ''Asperoris'' comes from
Manda Beds The Manda Formation (also known as the Manda Beds) is a Middle Triassic (Anisian?) or possibly Late Triassic (Carnian?) geologic formation in Tanzania. It preserves fossils of many terrestrial vertebrates from the Triassic, including some of the e ...
of the Ruhuhu Basin in
Songea Urban District Songea Urban District is one of the five districts in the Ruvuma Region of Tanzania. It is bordered to the north by the Songea Rural District, to the east by the Namtumbo District, to the south by Mozambique and to the west by the Mbinga Distri ...
of southwestern Tanzania, which dates back to the late
Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Trias ...
stage of the Middle Triassic. Based on field notes, NHMUK PV R36615 was found on August 23 in a drainage of the Hita River between the Njalila and Hiasi rivers also known as locality U9/1 of the Lifua Member of Manda Beds, near the remains of
dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typica ...
s. It was fully described in
2013 File:2013 Events Collage V2.png, From left, clockwise: Edward Snowden becomes internationally famous for leaking classified NSA wiretapping information; Typhoon Haiyan kills over 6,000 in the Philippines and Southeast Asia; The Dhaka garment ...
and assigned to a new genus and species, ''Asperoris mnyama'', by Sterling J. Nesbitt, Richard J. Butler and David J. Gower in the journal PLoS One. The generic name is derived from ''asper'', meaning "rough", and ''oris'', meaning "face" in
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
in reference to its rough and uniquely sculptured
skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, t ...
. The specific name ''mnyama'' means "beast" in
Swahili Swahili may refer to: * Swahili language, a Bantu language official in Kenya, Tanzania and Uganda and widely spoken in the African Great Lakes * Swahili people, an ethnic group in East Africa * Swahili culture Swahili culture is the culture of ...
.


Description

Like most archosauriforms from the Manda Beds, ''Asperoris'' is known from very fragmentary remains. NHMUK PV R36615 is distinguished from some other archosauriform material in the beds by the lack of a depression called an
antorbital fossa An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with archosauriforms, first appearing during the Triassic Period. Among extant archosaurs, birds ...
on the surfaces of its maxilla and premaxilla. Although it can not be directly compared with ''
Stagonosuchus ''Stagonosuchus'' is an extinct genus of loricatan, or possibly a species of ''Prestosuchus''. Fossils have been found from the Late Triassic Manda Formation in Tanzania that are Anisian in age. Unlike other rauisuchians, which have a prominent ...
'', ''
Hypselorhachis ''Hypselorhachis'' is a genus of extinct reptile, possibly a ctenosauriscid archosaur related to '' Ctenosauriscus''. It lived during the Triassic Period. It is currently known only from a single vertebra found from the Middle Triassic Manda Be ...
'', ''
Nyasasaurus ''Nyasasaurus'' (meaning " Lake Nyasa lizard") is an extinct genus of avemetatarsalian archosaur from the putatively Middle Triassic Manda Formation of Tanzania that may be the earliest known dinosaur. The type species ''Nyasasaurus parringt ...
'', ''
Teleocrater ''Teleocrater'' (meaning "completed basin", in reference to its closed acetabulum) is a genus of avemetatarsalian archosaur from the Middle Triassic Manda Formation of Tanzania. The name was coined by English paleontologist Alan Charig in his 195 ...
'' and an unnamed
suchia Suchia is a clade of archosaurs containing the majority of pseudosuchians (crocodilians and their extinct relatives). It was defined as the least inclusive clade containing ''Aetosaurus ferratus'', '' Rauisuchus tiradentes'', '' Prestosuchus ch ...
n, its inferred phylogenetic position is not consistent with it belonging to any of these taxa. The total length of the skull is estimated to have been in length. A unique characteristic or
autapomorphy 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 ...
of ''Asperoris'' is the rough texture of its skull bones, particularly the frontal. The
skull roof The skull roof, or the roofing bones of the skull, are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In comparati ...
of ''Asperoris'' is relatively thick compared to those of other archosauriforms and its
antorbital fenestra An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with archosauriforms, first appearing during the Triassic Period. Among extant archosaurs, birds ...
, a hole in the side of the skull in front of the eye socket, is relatively narrow.


Relationships

''Asperoris'' belongs to a clade or evolutionary grouping of reptiles called Archosauriformes, which includes
Archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avi ...
ia (the clade including living
crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest livi ...
ns and
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s) and their extinct, mostly Triassic, relatives. It has several features that place it outside Archosauria with non-archosaurian archosauriforms, including the lack of an antorbital fossa and the possible presence of a postparietal bone at the back of the skull, which is not found in archosaurs. However, it also has features that place it among the closest relatives of archosaurs, including the presence of an antorbital fenestra and the lack of a hole called the parietal foramen on the skull roof. ''Asperoris'' shares with a group of archosauriforms called
erythrosuchid Erythrosuchidae (meaning "red crocodiles" in Greek) are a family of large basal archosauriform carnivores that lived from the later Early Triassic (Olenekian) to the early Middle Triassic (Anisian). Naming The family Erythrosuchidae was named by ...
s the presence of slot in the lower part of the nasal bone that fits into a projection of the premaxilla beneath it. It also has a
thecodont Thecodontia (meaning 'socket-teeth'), now considered an obsolete taxonomic grouping, was formerly used to describe a diverse "order" of early archosaurian reptiles that first appeared in the latest Permian period and flourished until the end of ...
dentition, meaning that its teeth fit into deep sockets in the jaw. A thecodont dentition is seen in all non-archosaurian archosauriforms except
proterosuchid Proterosuchidae is an early family of basal archosauriforms whose fossils are known from the Latest Permian and the Early Triassic of Europe, Asia, Africa, Australia and possibly South America. The name comes from Greek πρότερο- ("first") ...
s, and is characteristic of the clade. Because of the poor preservation of NHMUK PV R36615 and the
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 ...
analysis used in the study (which focuses on relationships of Triassic archosaurs), the
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 ...
relationships of ''Asperoris'' are uncertain. Nesbitt, Butler and Gower's 2013 phylogenetic analysis resulted in a
strict consensus tree In mathematical writing, the term strict refers to the property of excluding equality and equivalence and often occurs in the context of inequality and monotonic functions. It is often attached to a technical term to indicate that the exclusi ...
with ''Asperoris'' in a
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 ...
or unresolved phylogenetic relationship with ''
Erythrosuchus africanus ''Erythrosuchus'' (from el, ἐρυθρός , 'red' and el, σοῦχος , 'crocodile') is an extinct genus of archosauriform reptile from the Triassic of South Africa. Remains have been found from the Cynognathus Assemblage Zone of the Bea ...
'', an erythrosuchid, '' Vancleavea campi'', an aquatic archosauriform, the proterosuchid clade, and the clade including ''
Euparkeria capensis ''Euparkeria'' (; meaning "Parker's good animal", named in honor of W.K. Parker) is an extinct genus of archosauriform from the Middle Triassic of South Africa. It was a small reptile that lived between 245-230 million years ago, and was close to ...
'',
phytosaur Phytosaurs (Φυτόσαυροι in greek) are an extinct group of large, mostly semiaquatic Late Triassic archosauriform reptiles. Phytosaurs belong to the order Phytosauria. Phytosauria and Phytosauridae are often considered to be equivalent gr ...
s, and Archosauria. Other phylogenetic trees produced in the analysis placed ''Asperoris'' as the
sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...
(closest relative) of either ''Erythrosuchus africanus'' or ''Euparkeria capensis''. A sister-taxon relationship with ''Erythrosuchus'' is more likely because it is based on a
derived Derive may refer to: * Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguatio ...
feature, the slot in the nasal, while the relationship with ''Euparkeria'' is less likely because it is based only on characteristics inherited from archosauriform ancestors (
plesiomorphies In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, an ...
). ''Asperoris'' was also featured in a phylogenetic analysis by
Martin Ezcurra Martin may refer to: Places * Martin City (disambiguation) * Martin County (disambiguation) * Martin Township (disambiguation) Antarctica * Martin Peninsula, Marie Byrd Land * Port Martin, Adelie Land * Point Martin, South Orkney Islands Austr ...
in 2016. Most parts of Ezcurra's analysis omitted this genus due to its incompleteness, but in versions which did feature it, it was found in a polytomy with ''
Yarasuchus ''Yarasuchus'' (meaning "red crocodile") is an extinct genus of avemetatarsalian archosaur that lived during the Anisian stage of the Middle Triassic of India.Bandyopadhyay, S. and Sengupta, D. P. (1999). Middle Triassic vertebrate faunas from ...
'', ''
Dongusuchus ''Dongusuchus'' (meaning ''Donguz River crocodile'' in Greek, for the area where the type specimen was foundSennikov, A. G. (1988) Novyye rauizukhidy iz triasa yevropeyskoy chasti SSSR. ''Paleontol. Zhurn.'' 1990 (2): 124-128 Moscow.) is an exti ...
'', ''
Dorosuchus ''Dorosuchus'' is an extinct genus of archosauriform previously assigned to the family Euparkeriidae. It lived during the Anisian stage of the Middle Triassic. Fossil material is known from Sol-Iletsk in Orenburg Oblast, Russia. The type species ...
'', and ''
Euparkeria ''Euparkeria'' (; meaning "Parker's good animal", named in honor of W.K. Parker) is an extinct genus of archosauriform from the Middle Triassic of South Africa. It was a small reptile that lived between 245-230 million years ago, and was close t ...
'' at the base of a clade which also includes
proterochampsia Proterochampsia is a clade of early archosauriform reptiles from the Triassic period. It includes the Proterochampsidae (e.g. ''Proterochampsa'', ''Chanaresuchus'' and ''Tropidosuchus'') and probably also the Doswelliidae. Nesbitt (2011) defin ...
ns and archosaurs. Ezcurra named this broad clade Eucrocopoda. The five-genus polytomy is resolved into a clearer system of clades when ''Asperoris'' is omitted, as the taxon's lack of postcranial features reduced the analysis's clarity. ''Yarasuchus'' and ''Dongusuchus'' are now considered to be aphanosaurs, part of a group of archosaurs at the base of the branch that leads to pterosaurs and dinosaurs (including birds) but not crocodiles.


References

{{Taxonbar, from=Q14949759 Middle Triassic reptiles of Africa Prehistoric archosauriforms Anisian life Triassic Tanzania Fossils of Tanzania Fossil taxa described in 2013 Prehistoric reptile genera