Owenetta

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Owenetta
Temporal range: 260.5–250  Ma
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Mid Wuchiapingian - early Induan
"Owenetta" kitchingorum.jpg
"Owenetta" kitchingorum
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Parareptilia
Order: Procolophonomorpha
Family: Owenettidae
Genus: Owenetta
Broom, 1939
Type species
Owenetta rubidgei
Broom, 1939
Synonyms
  • ?ColubriferCarroll, 1982
  • ?Colubrifer campiCarroll, 1982

Owenetta is an extinct genus of owenettid procolophonian parareptile. Fossils have been found from the Beaufort Group in the Karoo Basin of South Africa. Although most procolophonians lived during the Triassic, Owenetta existed during the Wuchiapingian and Changhsingian stages of the Late Permian as well as the early Induan stage of the Early Triassic. It is the type genus of the family Owenettidae, and can be distinguished from other related taxa in that the posterior portion of the supratemporal bears a lateral notch and that the pineal foramen is surrounded by a depressed parietal surface on the skull table.

Contents

Species

The type species of Owenetta is O. rubidgei. It is known from several skulls, but no postcranial skeleton. It was described in 1939 from a partial skull found from the Late Permian Cistecephalus Assemblage Zone of the Beaufort Group. [1] Several other localities, all from the overlying Dicynodon Assemblage Zone, have yielded the remainder of the known specimens.

The naming of a new species in 2002, O. kitchingorum, extended the temporal range of Owenetta into the Early Triassic, meaning that the genus had survived past the Permian–Triassic extinction event. [2] This new species was considered distinct from the type species based on features found from three nearly complete specimens that were present from the Lystrosaurus Assemblage Zone. Found in 1968, the first material of O. kitchingorum was a small block containing two skeletons in close proximity to one another (although at the time they were thought to be of the type species). [3] These skeletons provided much of the information used to distinguish O. kitchingorum from the type species. O. kitchingorum differed from O. rubidgei in that it possessed small postparietals on the posterior edge of the skull table and that the maxilla held no more than 20 teeth, some of which were caniniform. The best preserved specimen seems to be a subadult individual on the basis of features of the skull table.

A year after the new species of Owenetta was named, a paper proposed that it should be assigned to its own distinct genus, although a new name is yet to be provided. [4] A more recent paper also supported this polyphyly. [5] If this is the case, Owenetta is once again temporally restricted to the late Permian, and most likely died out at the end of the period as a result of the mass extinction event.

Later that year Colubrifer , named in 1982 from a specimen (UCMP 42773) found from the Early Triassic Lystrosaurus Assemblage Zone and thought to represent a short limbed lizard, was re-described. Based on a skull nearly identical to those known of Owenetta, it appears that the animal was a procolophonian almost certainly of that genus. It was found to be a junior synonym of Owenetta, but due to the poor preservation of its holotype, was reassigned Owenetta sp. [6]

Phylogenetics

When Owenetta was first named and described, it and other procolophonians were thought to be within Cotylosauria, a group that comprised what was believed to be the most primitive of reptiles. Cotylosauria has since been renamed Captorhinida, which is now thought to be a paraphyletic group anapsids and anapsid relatives. Owenetta and other procolophonians are now known to be within the subclass Parareptilia. It has later been placed within the family Nyctiphruretidae, but is currently placed within the family Owenettidae, of which it is the type genus. [7] [8] [9]

The well preserved, nearly complete specimens of Owenetta can be helpful in phylogenetic analyses of procolophonians and the parareptiles, which have recently undergone many great revisions. Although the postcranial skeleton is only known from immature individuals, comparisons can be made with related taxa such as Barasaurus , which is known from both immature and mature specimens, that resolve this morphology issue. Owenetta has been used in some phylogenetic analyses to uphold the traditional theory that the procolophonians were the ancestors of turtles, [10] although it now seems that turtles, if not Archosauromorpha, have evolved from parieasaurids [11] or even sauropterygians. [12]

Related Research Articles

<span class="mw-page-title-main">Anapsid</span> Subclass of reptiles

An anapsid is an amniote whose skull lacks one or more skull openings near the temples. Traditionally, the Anapsida are considered the most primitive subclass of amniotes, the ancestral stock from which Synapsida and Diapsida evolved, making anapsids paraphyletic. It is, however, doubtful that all anapsids lack temporal fenestra as a primitive trait, and that all the groups traditionally seen as anapsids truly lacked fenestra.

<i>Lystrosaurus</i> Genus of Late Permian and Early Triassic dicynodont therapsids

Lystrosaurus is an extinct genus of herbivorous dicynodont therapsids from the late Permian and Early Triassic epochs. It lived in what is now Antarctica, India, China, Mongolia, European Russia and South Africa. Four to six species are currently recognized, although from the 1930s to 1970s the number of species was thought to be much higher. They ranged in size from that of a small dog to 8 feet (2.5 meters) long.

<i>Milleretta</i> Extinct genus of reptiles

Milleretta is an extinct genus of millerettid parareptile from the Late Permian of South Africa. Fossils have been found in the Balfour Formation. Milleretta was a moderately sized, lizard-like animal, about 60 centimetres (24 in) in length. It was probably insectivorous. Its only known species is Milleretta rubidgei, making Milleretta a monospecific genus.

<span class="mw-page-title-main">Parareptilia</span> Extinct subclass of reptiles (306–201Ma ago)

Parareptilia ("near-reptiles") is an extinct subclass or clade of basal sauropsids/reptiles, typically considered the sister taxon to Eureptilia. Parareptiles first arose near the end of the Carboniferous period and achieved their highest diversity during the Permian period. Several ecological innovations were first accomplished by parareptiles among reptiles. These include the first reptiles to return to marine ecosystems (mesosaurs), the first bipedal reptiles, the first reptiles with advanced hearing systems, and the first large herbivorous reptiles. The only parareptiles to survive into the Triassic period were the procolophonoids, a group of small generalists, omnivores, and herbivores. The largest family of procolophonoids, the procolophonids, rediversified in the Triassic, but subsequently declined and became extinct by the end of the period.

<span class="mw-page-title-main">Procolophonia</span> Extinct suborder of reptiles

Procolophonia is an extinct suborder (clade) of herbivorous reptiles that lived from the Middle Permian till the end of the Triassic period. They were originally included as a suborder of the Cotylosauria but are now considered a clade of Parareptilia. They are closely related to other generally lizard-like Permian reptiles such as the Millerettidae, Bolosauridae, Acleistorhinidae, and Lanthanosuchidae, all of which are included under the Anapsida or "Parareptiles".

<span class="mw-page-title-main">Procolophonomorpha</span> Order of reptiles (fossil)

Procolophonomorpha is an order or clade containing most parareptiles. Many papers have applied various definitions to the name, though most of these definitions have since been considered synonymous with modern parareptile clades such as Ankyramorpha and Procolophonia. The current definition of Procolophonomorpha, as defined by Modesto, Scott, & Reisz (2009), is that of as a stem-based group containing Procolophon and all taxa more closely related to it than to Milleretta. It constitutes a diverse assemblage that includes a number of lizard-like forms, as well as more diverse types such as the pareiasaurs. Lee 1995, 1996, 1997 argues that turtles evolved from pareiasaurs, but this view is no longer considered likely. Rieppel and deBraga 1996 and deBraga and Rieppel, 1997 argue that turtles evolved from sauropterygians, and there is both molecular and fossil (Pappochelys) evidence for the origin of turtles among diapsid reptiles.

<i>Proterosuchus</i> Extinct genus of reptiles from the Early Triassic of South Africa

Proterosuchus is an extinct genus of archosauriform reptiles that lived during the Early Triassic. It contains three valid species: the type species P. fergusi and the referred species P. alexanderi and P. goweri. All three species lived in what is now South Africa. The genus was named in 1903 by the South African paleontologist Robert Broom. The genus Chasmatosaurus is a junior synonym of Proterosuchus.

<i>Lystrosaurus</i> Assemblage Zone

The Lystrosaurus Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the upper Adelaide and lower Tarkastad Subgroups of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. This biozone has outcrops in the south central Eastern Cape and in the southern and northeastern Free State. The Lystrosaurus Assemblage Zone is one of eight biozones found in the Beaufort Group, and is considered to be Early Triassic in age.

<span class="mw-page-title-main">Procolophonidae</span> Extinct family of reptiles

Procolophonidae is an extinct family of small, lizard-like parareptiles known from the Late Permian to Late Triassic that were distributed across Pangaea, having been reported from Europe, North America, China, South Africa, South America, Antarctica and Australia. The most primitive procolophonids were likely insectivorous or omnivorous, more derived members of the clade developed bicusped molars, and were likely herbivorous feeding on high fiber vegetation or durophagous omnivores. Many members of the group are noted for spines projecting from the quadratojugal bone of the skull, which likely served a defensive purpose as well as possibly also for display. At least some taxa were likely fossorial burrowers. While diverse during the Early and Middle Triassic, they had very low diversity during the Late Triassic, and were extinct by the beginning of the Jurassic.

<i>Procolophon</i> Extinct genus of reptiles

Procolophon is a genus of lizard-like procolophonid parareptiles that first appeared in the Early Triassic (Induan) of South Africa, Brazil, and Antarctica. It persisted through the Permian–Triassic extinction event, but went extinct in the beginning of the Early Middle Triassic. The type species is P. trigoniceps.

<i>Macroleter</i> Extinct genus of reptiles

Macroleter is an extinct genus of nycteroleterid parareptile which existed in Oklahoma and Russia during the upper Permian period. It was a quite generalized primitive reptile, in many ways resembling their amphibian ancestors. It was first named by paleontologists Tverdochlebova and Ivachnenko in 1984. According to classification by Michel Laurin and Robert R. Reisz, the genus is a parareptile, belonging to the same branch as Millerettidae, Procolophonidae and other generalized anapsid reptiles. The type species is Macroleter poezicus from Upper Permian of Russia.

<i>Colobomycter</i> Extinct genus of reptiles

Colobomycter is an extinct genus of acleistorhinid parareptile known from the Early Permian of Oklahoma.

<i>Lydekkerina</i> Extinct genus of temnospondyls from the Early Triassic

Lydekkerina is an extinct genus of stereospondyl temnospondyl. It is the type genus of the family Lydekkerinidae. Fossils have been collected from Early Triassic deposits in South Africa and Australia. The type species is L. huxleyi, first described in 1889. While most other stereospondyls were semiaquatic, Lydekkerina was exclusively terrestrial.

<i>Acleistorhinus</i> Extinct genus of reptiles

Acleistorhinus (ah-kles-toe-RYE-nuss) is an extinct genus of parareptile known from the Early Permian of Oklahoma. It is notable for being the earliest known anapsid reptile yet discovered. The morphology of the lower temporal fenestra of the skull of Acleistorhinus bears a superficial resemblance to that seen in early synapsids, a result of convergent evolution. Only a single species, A. pteroticus, is known, and it is classified in the Family Acleistorhinidae, along with Colobomycter.

<span class="mw-page-title-main">Owenettidae</span> Extinct family of reptiles

Owenettidae is an extinct family of procolophonian parareptiles. Fossils have been found primarily from Africa and Madagascar, with one genus present from South America. It is the sister taxon to the family Procolophonidae. Modesto and Damiani (2007) defined Owenettidae as a stem-based group including Owenetta rubidgei and all species closely related to it than to Procolophon trigoniceps.

<span class="mw-page-title-main">Procolophonoidea</span> Extinct superfamily of reptiles

Procolophonoidea is an extinct superfamily of procolophonian parareptiles. Members were characteristically small, stocky, and lizard-like in appearance. Fossils have been found worldwide from many continents including Antarctica. The first members appeared during the Late Permian in the Karoo Basin of South Africa.

<span class="mw-page-title-main">Evolution of reptiles</span> Origin and diversification of reptiles through geologic time

Reptiles arose about 320 million years ago during the Carboniferous period. Reptiles, in the traditional sense of the term, are defined as animals that have scales or scutes, lay land-based hard-shelled eggs, and possess ectothermic metabolisms. So defined, the group is paraphyletic, excluding endothermic animals like birds that are descended from early traditionally-defined reptiles. A definition in accordance with phylogenetic nomenclature, which rejects paraphyletic groups, includes birds while excluding mammals and their synapsid ancestors. So defined, Reptilia is identical to Sauropsida.

<i>Sauropareion</i> Extinct genus of reptiles

Sauropareion is an extinct genus of basal procolophonid parareptile from earliest Triassic deposits of Eastern Cape Province, South Africa. It is known from the holotype SAM PK-11192, skull and partial postcranium. It was collected by the late L. D. Boonstra in 1935 from Barendskraal in the Middelburg District and referred to the Lystrosaurus Assemblage Zone of the Beaufort Group. It was first named by Sean P. Modesto, Hans-Dieter Sues and Ross J. Damiani in 2001 and the type species is Sauropareion anoplus. The generic name means "lizard", sauros, and "cheek", pareion from Greek in reference to the lizard-like appearance of the temporal region. The specific name comes from the Greek word anoplos, meaning "without arms or armour".

<i>Barasaurus</i> Extinct genus of reptiles

Barasaurus is an extinct genus of owenettid procolophonoid parareptile known from the Late Permian and Early Triassic of Madagascar. It contains a single species, Barasaurus besairiei.

Saurodektes is an extinct genus of owenettid procolophonoid parareptile known from the earliest Triassic deposits of Eastern Cape Province, South Africa. It was first named by Sean P. Modesto, Ross J. Damiani, Johann Neveling and Adam M. Yates in 2003 and the type species is Saurodectes rogersorum. The generic name Saurodectes was preoccupied by the generic name of Saurodectes vrsanskyi Rasnitsyn & Zherikhin, 2000, a fossil chewing lice known from the Early Cretaceous of Russia. Thus, an alternative generic name, Saurodektes, was proposed by Modesto et al. in 2004. The generic name means "lizard", sauros, and "biter", dektes from Greek. The specific name, rogersorum, honors Richard and Jenny Rogers, owners of the farm Barendskraal, for their hospitality, support and interest in the work of the paleontologists who recovered the holotype. Saurodektes is known solely from the holotype BP/1/6025, a partial skull and some fragmentary partial postcranial elements, housed at the Bernard Price Institute for Palaeontological Research, although the unprepared specimens BP/1/6044, BP/1/6045 and BP/1/6047 might also be referable to it. All specimens were collected on the slopes of the Manhaar Hill at Barendskraal in the Middelburg District, from the Palingkloof Member of the Balfour Formation, Beaufort Group, only 12 metres below the base of the Katberg Formation. This horizon belongs to the Lystrosaurus Assemblage Zone, dating to the early Induan stage of the Early Triassic period.

References

  1. Broom, R. (1939). A new type of cotylosaurian, Owenetta rubidgei. Annals of the Transvaal Museum19:319–321.
  2. Reisz, R. R. and Scott, D. (2002). Owenetta kitchingorum, sp. nov., a small parareptile (Procolophonia: Owenettidae) from the Lower Triassic of South Africa. Journal of Vertebrate Paleontology22(2):244-256.
  3. Gow, C. E. (1977). Owenetta in perspective. Palaeontologica Africana20:115–118.
  4. Modesto, S. P., Damiani, R. J., Neveling, J. and Yates, A. M. (2003). A new Triassic owenettid parareptile and the Mother of Mass Extinctions. Journal of Vertebrate Paleontology23(3):715–719.
  5. Modesto, S. P. and Damiani, R. (2007). The Procolophonoid Reptile Sauropareion anoplus from the Lowermost Triassic of South Africa. Journal of Vertebrate Paleontology27(2):337-349
  6. Evans, S. E. (2001). "The Early Triassic 'lizard' Colubrifer Campi: A Reassessment". Palaeontology. 44 (5): 1033–1041. Bibcode:2001Palgy..44.1033E. doi: 10.1111/1475-4983.00214 .
  7. Lee, M. S. Y. (1995). Historical burden in systematics and the interrelationships of parareptiles. Biological Reviews70(3):459-547.
  8. deBraga, M. and Reisz, R. (1996). The Early Permian reptile Acleistorhinus pteroticus and its phylogenetic position. Journal of Vertebrate Paleontology16(3):384-395
  9. Säilä, L. K. (2008). The osteology and affinities of Anomoiodon liliensterni, a procolophonid reptile from the Lower Triassic Buntsandstein of Germany. Journal of Vertebrate Paleontology28(4):1199-1205
  10. Reisz, R. R. and Laurin, M. (1991). Owenetta and the origin of turtles. Nature349:324-326.
  11. Lee, M. S. Y. (1997). Pareiasaur phylogeny and the origin of turtles. Zoological Journal of the Linnean Society120:197-280
  12. Rieppel, O. and deBraga, M. (1996). Turtles as diapsid reptiles. Nature384:453-455.