Macroscelesaurus

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Macroscelesaurus
Temporal range: Late Permian
Macroscelesaurus janseni Haughton.jpg
Illustration of the holotype skeleton of Macroscelesaurus janseni, 1918
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Clade: Therapsida
Suborder: Therocephalia
Superfamily: Baurioidea
Genus: Macroscelesaurus
Haughton, 1918
Type species
Macroscelesaurus janseni
Haughton, 1918
Synonyms
  • Haughtoniscus Kuhn, 1934

Macroscelesaurus is an extinct genus of therocephalian therapsid from the Late Permian of South Africa. The type species Macroscelesaurus janseni was named by Sidney H. Haughton in 1918 from the Cistecephalus Assemblage Zone. It is one of the few therocephalians known from postcranial remains. [1]

Contents

Description and history

Macroscelesaurus is known from a single holotype consisting of the mold of a partial skeleton. The impression was found on a sandstone block that made up the wall of a kraal or sheep enclosure near the town of Victoria West. It includes most of the postcranial skeleton, including the vertebral column, ribs, limbs, and the pelvic and pectoral girdles. Most of the skull is not preserved. The skeleton is preserved in ventral view, with the body curving to the right and the limbs bent to one side. The specimen was brought to South African paleontologist Sidney H. Haughton, and formally described the next year. On the basis of the impression, Haughton designated the species Macroscelesaurus janseni, after the discoverer of the specimen, F. J. Jansen. Although it was not found in a deposit, Haughton thought that the specimen originated from rock layers belonging to the Tapinocephalus Assemblage Zone. The fossil is now thought to have been from the younger Cistecephalus Assemblage Zone. [2]

German paleontologist Oskar Kuhn renamed Macroscelesaurus as Haughtoniscus in 1934, as he thought the original name was too similar to Macroscelosaurus , the generic name for a prolacertiform reptile that had described in 1852. [3] Under the rules of the International Code of Zoological Nomenclature, Kuhn's renaming was inappropriate and the name Macroscelesaurus is still considered valid.

Classification

Haughton considered placing it within Dromasauria, a group of small anomodont therapsids. Most similarities between the two therapsids were seen in the limbs. He noted several differences, including the relatively large hind limbs of Macroscelesaurus (the fore and hind limbs of dromasaurians are about equal in length) and enlarged canines, which are not seen in dromasaurians. Haughton also considered the possibility that Macroscelesaurus was a therocephalian therapsid, because it shared more features in common with Ictidosuchus than any other therapsid. [2]

Macroscelesaurus is now classified in the therocephalian clade Baurioidea, although its exact position is uncertain. [4]

Related Research Articles

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Diictodon was a genus of pylaecephalid dicynodont. These mammal-like synapsids lived during the Late Permian period, approximately 255 million years ago. Fossils have been found in the Cistecephalus Assemblage Zone of the Madumabisa Mudstone of the Luangwa Basin in Zambia and the Tropidostoma Assemblage Zone of the Teekloof Formation, Tapinocephalus Assemblage Zone of the Abrahamskraal Formation, Dicynodon Assemblage Zone of the Balfour Formation, Cistecephalus Assemblage Zone of the Middleton or Balfour Formation of South Africa and the Guodikeng Formation of China. Roughly half of all Permian vertebrate specimens found in South Africa are those of Diictodon. This small herbivorous animal was one of the most successful synapsids in the Permian period.

<i>Gorgonops</i>

Gorgonops is an extinct genus of therapsid which lived about 260-254 million years ago, during the Late Permian. It was a typical representative of the suborder Gorgonopsia, the dominant predators of their day, which in the largest forms grew to over three metres long.

<i>Dinogorgon</i>

Dinogorgon is a genus of gorgonopsid from the Late Permian of South Africa and Tanzania. The generic name Dinogorgon is derived from Greek, meaning "terrible gorgon", while its species name rubidgei is taken from the surname of renowned Karoo paleontologist, Professor Bruce Rubidge, who has contributed to much of the research conducted on therapsids of the Karoo Basin. The type species of the genus is D. rubidgei.

<i>Cistecephalus</i> Assemblage Zone

The Cistecephalus Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important geological group of the Karoo Supergroup in South Africa. This biozone has outcrops located in the Teekloof Formation north-west of Beaufort West in the Western Cape, in the upper Middleton and lower Balfour Formations respectively from Colesberg of the Northern Cape to east of Graaff-Reinet in the Eastern Cape. The Cistecephalus Assemblage Zone is one of eight biozones found in the Beaufort Group, and is considered to be Late Permian in age.

<i>Euchambersia</i> Extinct genus of therapsid from Late Permian South Africa

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<i>Eodicynodon</i>

Eodicynodon is an extinct genus of dicynodont therapsids, a highly diverse group of herbivorous synapsids that were widespread during the middle-late Permian and early Triassic. As its name suggests, Eodicynodon is the oldest and most primitive dicynodont yet identified, ranging from the middle to late Permian and possessing a mix of ancestral Anomodont/therapsid features and derived dicynodont synapomorphies.

<i>Aelurognathus</i>

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<i>Theriognathus</i> Extinct genus of therapsids from late Permian South Africa and Tanzania

Theriognathus is an extinct genus of therocephalian therapsid belonging to the family Whaitsiidae, from South Africa and Tanzania. Theriognathus has been dated as existing during the Late Permian. Although Theriognathus means mammal jaw, the lower jaw is actually made up of several bones as seen in modern reptiles, in contrast to mammals. Theriognathus displayed many different reptilian and mammalian characteristics. For example, Theriognathus had canine teeth like mammals, and a secondary palate, multiple bones in the mandible, and a typical reptilian jaw joint, all characteristics of reptiles. It is speculated that Theriognathus was either carnivorous or omnivorous based on its teeth, and was suited to hunting small prey in undergrowth. This synapsid adopted a sleek profile of a mammalian predator, with a narrow snout and around 1 meter long. Theriognathus is represented by 56 specimens in the fossil record.

<i>Regisaurus</i> Genus of therapsids from the Early Triassic of South Africa

Regisaurus is an extinct genus of small carnivorous therocephalian. It is known from a single described species, the type species Regisaurus jacobi, from the Early Triassic Lystrosaurus Assemblage Zone of South Africa, although at least one undescribed species is also known.

<i>Lydekkerina</i> Extinct genus of amphibians 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.

Eosimops is an extinct genus of pylaecephalid dicynodonts. They were small synapsids superficially resembling modern mammals. Eosimops is known from several skull specimens, as well as one complete skeleton. Eosimops lived during the Middle Permian of South Africa.

<i>Owenetta</i>

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.

<i>Aulacephalodon</i>

Aulacephalodon is an extinct genus of medium-sized dicynodonts, or non-mammalian synapsids, that lived during Permian period, about 299-252 million years ago. Individuals of Aulacephalodon are commonly found in the Lower Beaufort Group of the Karoo Supergroup of South Africa and Zambia. Rising to dominance during the Late Permian, Aulacephalodon were the dominant terrestrial vertebrate herbivores until they became extinct during the Triassic. No living relatives of Aulacephalodon exist today. Two species have been named, the type species, A. bainii, and a second species, A. peavoti. However, debate exists among paleontologists if A. peavoti is a true member of the genus Aulacephalodon. Therefore, a majority of the information known about Aulacephalodon is in reference to discoveries about A. bainii.

Akidnognathidae

Akidnognathidae is an extinct family of therocephalian therapsids from the Late Permian and Early Triassic of South Africa and Russia. The family includes many large-bodied therocephalians that were probably carnivorous, including Moschorhinus and Olivierosuchus. One akidnognathid, Euchambersia, may even have been venomous. Akidnognathids have robust skulls with a pair of large caniniform teeth in their upper jaws. The family is morphologically intermediate between the more basal therocephalian group Scylacosauridae and the more derived group Baurioidea.

<i>Choerosaurus</i> Genus of therapsids from the Late Permian of South Africa

Choerosaurus is an extinct genus of therocephalian therapsids from the Late Permian of South Africa. The type species Choerosaurus dejageri was named by South African paleontologist Sidney H. Haughton from the Tropidostoma Assemblage Zone in 1929.

Blattoidealestes is an extinct genus of therocephalian therapsid from the Middle Permian of South Africa. The type species Blattoidealestes gracilis was named by South African paleontologist Lieuwe Dirk Boonstra from the Tapinocephalus Assemblage Zone in 1954. Dating back to the Middle Permian, Blattoidealestes is one of the oldest therocephalians. It is similar in appearance to the small therocephalian Perplexisaurus from Russia, and may be closely related.

Homodontosaurus is an extinct genus of therocephalian therapsids from the Late Permian of South Africa. The type species Homodontosaurus kitchingi was named by South African paleontologist Robert Broom in 1949. Broom based his description on a small skull found in the Cistecephalus Assemblage Zone near Graaff-Reinet. The skull is very small, at about 55 millimetres (2.2 in) long and 20 millimetres (0.79 in) wide. Homodontosaurus has large eye sockets and an elongated snout. The lower jaw is long, thin, and curved. Numerous small teeth line the upper jaw and are long, pointed, and round in cross-section.

Icticephalus is an extinct genus of therocephalian therapsids from the Middle and Late Permian of South Africa. The type species Icticephalus polycynodon was named from the Tapinocephalus Assemblage Zone by South African paleontologist Robert Broom in 1915. Specimens of Icticephalus have also been described from the Cistecephalus Assemblage Zone. Broom originally placed Icticephalus in the Scaloposauridae, a group of very small therocephalians. Most scaloposaurids are now thought to be juvenile forms of other therocephalians, and Scaloposauridae is no longer recognized as a valid grouping. Icticephalus and other former scaloposaurids are now classified as basal members of Baurioidea.

Polycynodon is an extinct genus of therocephalians from the Late Permian of South Africa. It is known from the Cistecephalus Assemblage Zone. The type species was first described as Octocynodon elegans by South African paleontologist Robert Broom in 1940, but the name Octocynodon was preoccupied by a genus of labrid fish first described in 1904. Along with John T. Robinson, Broom instated Polycynodon as a replacement name for O. elegans in 1948. Polycynodon is classified in Baurioidea, although its relationship to other baurioid therocephalians is uncertain.

Pelictosuchus is an extinct genus of therocephalian therapsids from the Late Permian of South Africa. It is classified in the family Akidnognathidae. The type species Pelictosuchus paucidens was named by South African paleontologist Robert Broom in 1940 from the Dicynodon Assemblage Zone.

References

  1. Botha-Brink, J.; Modesto, S. P. (2011). "A new skeleton of the Therocephalian synapsid Olivierosuchus parringtoni from the Lower Triassic South African Karoo Basin". Palaeontology. 54 (3): 591–606. doi: 10.1111/j.1475-4983.2011.01048.x .
  2. 1 2 Haughton, S.H. (1918). "Some new carnivorous Therapsida, with notes upon the braincase in certain species". Annals of the South African Museum. 12: 175–216.
  3. Mortimer, M. (30 July 2010). "Procerosaurus and Macroscelosaurus- two Tanystropheus". The Theropod Database Blog. Blogger. Retrieved 18 February 2012.
  4. Ivakhnenko, M.F. (2011). "Permian and Triassic therocephals (Eutherapsida) of Eastern Europe". Paleontological Journal. 45 (9): 981–1144. doi:10.1134/S0031030111090012.