Biarmosuchia

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Biarmosuchia
Temporal range: Middle Permian - Late Permian, 272.5–252  Ma
Biarmosuchus tener (1).jpg
Mounted skeleton of Biarmosuchus tener
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Suborder: Biarmosuchia
Sigogneau-Russell, 1989
Subgroups

Biarmosuchia is an extinct clade of non-mammalian synapsids from the Permian. Biarmosuchians are the most basal group of the therapsids. They were moderately-sized, lightly built carnivores, intermediate in form between basal sphenacodont "pelycosaurs" and more advanced therapsids. Biarmosuchians were rare components of Permian ecosystems, and the majority of species belong to the clade Burnetiamorpha, which are characterized by elaborate cranial ornamentation.

Contents

Characteristics

Proburnetia, a biarmosuchian with strange bumps and bosses on its skull, from the Late Permian of Russia Proburnetia BW.jpg
Proburnetia , a biarmosuchian with strange bumps and bosses on its skull, from the Late Permian of Russia

The biarmosuchian skull is very similar to the sphenacodontid skull, differing only in the larger temporal fenestra (although these are still small relative to later therapsids), slightly backward-sloping occiput (the reverse of the pelycosaur condition), reduced number of teeth, and single large canine teeth in both upper and lower jaws, and other features (Carroll 1988 pp. 370, Benton 2000 p. 114). In later specialised Biarmosuchia, these resemble the enlarged canines of the Gorgonopsia. The presence of larger jaw-closing muscles (and hence a stronger bite) is indicated by the flaring of the rear of the skull where these muscles were attached. Burnetiamorphs, which made up the majority of biarmosuchian diversity, were characterized by elaborate cranial ornamentation consisting of bumps and bosses. [1] Some burnetiids have a thick domed skull reminiscent of dinocephalians and pachycephalosaur dinosaurs. [2]

The vertebrae are also sphenacodontid-like (but lack the long neural spines that distinguish Dimetrodon and its kin), but the shoulder and pelvic girdles and the limbs indicate a much more advanced posture. The feet are more symmetrical, indicating that they faced forward throughout the stride, and the phalanges (fingers/toes) are reduced in length so that they are more like that of later synapsids (therapsids and mammals) (Carroll 1988 pp. 370–1).

Biarmosuchians ranged in size from relatively small species with skulls 10–15 cm in length to large species such as Biarmosuchus , which may have had a skull 60 centimetres (24 in) in length. [2]

Distribution

Currently the most representative group of the Biarmosuchia, the Burnetiamorpha, comprise ten genera: Bullacephalus , Burnetia , Lemurosaurus , Lobalopex , Lophorhinus , Paraburnetia , and Pachydectes from South Africa, Niuksenitia and Proburnetia from Russia, and Lende (MAL 290) from Malawi. [3] In addition, Sidor et al. (2010) [4] recently described a partial skull roof including the dorsal margin of orbits and parietal foramen of an unnamed burnetiid from the upper Permian of Tanzania, and Sidor et al. (2014) [5] noted the presence of a burnetiid in the middle Permian of Zambia. Other Biarmosuchia include Biarmosuchus from Russia, Hipposaurus , Herpetoskylax , Ictidorhinus and Lycaenodon from South Africa, and Wantulignathus from Zambia. [1]

Classification

Phylogeny of Biarmosuchia from Day et al., 2018 [6]

Biarmosuchians are typically considered the most basal major lineage of therapsids. [2] Biarmosuchia consists of a paraphyletic series of basal biarmosuchians that are fairly typical early therapsids, and the derived clade Burnetiamorpha, characterized by skulls ornamented by horns and bosses.

Taxonomic history

Biarmosuchians were the last of the six major therapsid lineages to be recognized. [2] The majority of biarmosuchians were once considered gorgonopsians. James Hopson and Herbert Richard Barghusen (1986 p. 88) tentatively united Biarmosuchidae and Ictidorhinidae (including Hipposauridae and Rubidginidae) as "Biarmosuchia", but were undecided as to whether they constituted a natural group or an assemblage that had in common only shared primitive characteristics. They thought that Phthinosuchus was too poorly known to tell if it also belonged, but considered Eotitanosuchus a more advanced form. [7]

Denise Sigogneau-Russell (1989) erected the infraorder Biarmosuchia to include the families Biarmosuchidae, Hipposauridae and Ictidorhinidae, distinct from Eotitanosuchia and Phthinosuchia.

Ivakhnenko (1999) argued that Biarmosuchus tener, Eotitanosuchus olsoni, and Ivantosaurus ensifer, all known from the Ezhovo locality, Ocher Faunal Assemblage, are actually the same species. Even if these taxa are shown to be distinct, Ivakhnenko's paper indicates that Eotitanosuchus and Biarmosuchus are very similar animals. Ivakhnenko also relocates the family Eotitanosuchidae to the order Titanosuchia, superorder Dinocephalia.

Benton 2000 and 2004 [8] gives the Biarmosuchia the rank of suborder.

Paleoecology

Biarmosuchians were rare components of their ecosystems; only one specimen is known for most species. [2] However, they were moderately diverse and there were multiple contemporary species in some ecosystems. [9] All were predators similar to gorgonopsians and therocephalians, though they were generally not apex predators.

See also

Related Research Articles

<span class="mw-page-title-main">Therapsida</span> Clade of tetrapods including mammals

Therapsida is a clade comprising a major group of eupelycosaurian synapsids that includes mammals and their ancestors and close relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more underneath the body, resulting in a more "standing" quadrupedal posture, as opposed to the lower sprawling posture of many reptiles and amphibians.

<i>Biarmosuchus</i> Extinct genus of therapsids

Biarmosuchus is an extinct genus of biarmosuchian therapsids that lived around 267 mya during the Middle Permian period. Biarmosuchus was discovered in the Perm region of Russia. The first specimen was found in channel sandstone that was deposited by flood waters originating from the young Ural Mountains.

<i>Eotitanosuchus</i> Extinct genus of therapsids

Eotitanosuchus is an extinct genus of biarmosuchian therapsids whose fossils were found in the town of Ochyor in Perm Krai, Russia. It lived about 267 million years ago. The only species is Eotitanosuchus olsoni.

<span class="mw-page-title-main">Therocephalia</span> Extinct order of therapsids

Therocephalia is an extinct clade of eutheriodont therapsids from the Permian and Triassic periods. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores. Like other non-mammalian synapsids, therocephalians were once described as "mammal-like reptiles". Therocephalia is the group most closely related to the cynodonts, which gave rise to the mammals, and this relationship takes evidence in a variety of skeletal features. Indeed, it had been proposed that cynodonts may have evolved from therocephalians and so that therocephalians as recognised are paraphyletic in relation to cynodonts.

<i>Dinogorgon</i> Extinct genus of therapsids

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.

<span class="mw-page-title-main">Burnetiidae</span> Extinct family of therapsids

Burnetiidae is an extinct family of biarmosuchian therapsids that lived in the Permian period whose fossils are found in South Africa, Zambia and Russia. It contains Bondoceras, Bullacephalus, Burnetia, Mobaceras, Niuksenitia, Paraburnetia and Proburnetia.

<i>Lemurosaurus</i> Extinct genus of therapsids

Lemurosaurus is a genus of extinct biarmosuchian therapsids from the Late Permian of South Africa. The generic epithet Lemursaurus is a mix of Latin, lemures “ghosts, spirits”, and Greek, sauros, “lizard”. Lemurosaurus is easily identifiable by its prominent eye crests, and large eyes. The name Lemurosaurus pricei was coined by paleontologist Robert Broom in 1949, based on a single small crushed skull, measured at approximately 86 millimeters in length, found on the Dorsfontein farm in Graaff-Reinet. To date, only two skulls of the Lemurosaurus have been discovered, so body size is unknown. The second larger, more intact, skull was found in 1974 by a team from the National Museum, Bloemfontein.

<i>Paraburnetia</i> Extinct genus of therapsids

Paraburnetia is an extinct genus of biarmosuchian therapsids from the Late Permian of South Africa. It is known for its species P. sneeubergensis and belongs to the family Burnetiidae. Paraburnetia lived just before the Permian–Triassic mass extinction event.

<i>Lobalopex</i> Extinct genus of therapsids

Lobalopex is an extinct genus of biarmosuchian therapsids. It was alive during the Late Permian and has only been found in the Teekloof Formation in South Africa. The only known species of the genus is Lobalopex mordax. Lobalopex is part of the clade of Burnetiamorpha, which have fossil specimens located in multiple areas of Africa and Russia.

<i>Bullacephalus</i> Extinct genus of animal

Bullacephalus is an extinct genus of biarmosuchian therapsids belonging to the family Burnetiidae. The type species B. jacksoni was named in 2003. It is known from a relatively complete skull and lower jaw, discovered in the Late Permian Tapinocephalus Assemblage Zone of the Beaufort Group of South Africa. This genus of therapsida lived during the Late Permian period, approximately 250 million years ago. The name Bullacephalus comes from the Latin words "bullatus," meaning "bossed" or "knobbed," and "cephalus," meaning "head." This name refers to the distinctive bony knob on the top of the therapsid's skull, which contributes to the history of this genus. This stem based taxon includes Ictidorhinus or Hippasaurs. Bullacephalus can even be characterized as having a, “skull moderately to greatly pachyostotic; swollen boss present above the postorbital bar formed by the postfrontal and postorbital; deep linear sculpturing of the snout; exclusion of the jugal from the lateral temporal fenestra”. These Therapsids have spongy bone skull roof, palatal process of premaxilla are long, diverticulum of naris adding them to the Burnetiamorph. Furthermore, the discovery of Bullacephalus has helped to refine the taxonomic classification of therapsids. Prior to its discovery, there was uncertainty regarding the relationship between different groups of therapsids, particularly the Burnetiamorpha and the Biarmosuchia. However, the distinctive features of Bullacephalus suggest that it is a member of the Burnetiamorpha, and provides a bridge between this group and the Biarmosuchia. The discovery of Bullacephalus has also highlighted the importance of continued exploration and excavation in areas that have yielded few therapsid fossils. The Beaufort Group of South Africa, where Bullacephalus was discovered, has been an important site for therapsid fossils, but much of the area remains unexplored. Further discoveries in this region and other areas around the world may provide new insights into the evolution and diversification of therapsids, as well as other groups of extinct animals. These discoveries will also help to refine our understanding of the history of life on Earth and the processes that have shaped the diversity of organisms that exist today.

<i>Chthonosaurus</i> Extinct genus of therapsids from the Late Permian of Russia

Chthonosaurus is an extinct genus of eutherocephalian therapsids from the Late Permian Kutulukskaya Formation of Russia. The type species Chthonosaurus velocidens was named in 1955.

Eosyodon is a dubious genus of extinct non-mammalian synapsids from the Permian of Texas. Its type and only species is Eosyodon hudsoni. Though it was originally interpreted as an early therapsid, it is probably a member of Sphenacodontidae, the family of synapsids that includes Dimetrodon.

<i>Ictidorhinus</i> Extinct genus of therapsids

Ictidorhinus is an extinct genus of biarmosuchian therapsids. Fossils have been found from the Dicynodon Assemblage Zone of the Beaufort Group in the Karoo Basin, South Africa and are of Late Permian age. It had a short snout and proportionally large orbits. These characteristics may be representative of a juvenile animal, possibly of Lycaenodon. However, these two genera are not known to have existed at the same time, making it unlikely for Ictidorhinus material to be from a juvenile form of Lycaenodon.

Lycaenodon is an extinct genus of biarmosuchian therapsids from the Late Permian of South Africa. It is known from a single species, Lycaenodon longiceps, which was named by South African paleontologist Robert Broom in 1925. Both are small-bodied biarmosuchians. Two specimens are known, and both preserve only the front portions of the skull. These specimens come from the Cistecephalus Assemblage Zone of the Karoo Basin. Broom attributed the back portion of a third skull to Lycaenodon, but subsequent examiners considered it to belong to a gorgonopsian or dinocephalian and not a biarmosuchian. Most of the distinguishing features of Lycaenodon come from its palate. As a member of Biarmosuchia, the most basal group of therapsids, Lycaenodon shares many features with earlier and less mammal-like synapsids like Dimetrodon.

<i>Pristerodon</i> Extinct genus of dicynodont therapsid from the late Permian

Pristerodon is an extinct genus of dicynodont therapsid from the Late Permian of South Africa, Zambia and India.

<i>Raranimus</i> Extinct genus of therapsids

Raranimus is an extinct genus of therapsids of the Middle Permian. It was described in 2009 from a partial skull found in 1998 from the Dashankou locality of the Qingtoushan Formation, outcropping in the Qilian Mountains of Gansu, China. The genus is the most basal known member of the clade Therapsida, to which the later Mammalia belong.

Christian Alfred Sidor is an American vertebrate paleontologist. He is currently a Professor in the Department of Biology, University of Washington in Seattle, as well as Curator of Vertebrate Paleontology and Associate Director for Research and Collections at the Burke Museum of Natural History and Culture. His research focuses on Permian and Triassic tetrapod evolution, especially on therapsids.

<i>Lende</i> Extinct genus of therapsids

Lende is an extinct genus of biarmosuchian from Malawi. It contains one species, Lende chiweta, first described by Jacobs and colleagues in 2005 and is a burnetiamorph – a group of biarmosuchians characterized by numerous bosses and swellings on the skull. The type specimen was discovered in the early 1990s in the Permian Lower Bone Bed (B1) of the Chiweta Beds of Malawi, which are believed to correlate with the Cistecephalus Assemblage Zone of the South African Karoo Supergroup, the Usili Formation of Tanzania, and the Upper Madumabisa Mudstone of Zambia. The holotype of the genus Lende is MAL 290, which comprises an almost complete skull and lower jaw.

<i>Leucocephalus</i> Extinct genus of therapsids

Leucocephalus is a genus of biarmosuchian belonging to the family Burnetiidae dating to the Wuchiapingian. It was found in the Tropidostoma Assemblage Zone of the Main Karoo Basin of South Africa. It is a monotypic taxon which contains one only species, Leucocephalus wewersi. The genus name Leucocephalus is derived from Greek. Leucos, meaning white; kephalos, meaning skull, as the Leucocephalus skull discovered was unusually pale. The species epithet wewersi comes from the farm employee who found the skull, Klaus ‘Klaasie’ Wewers.

References

  1. 1 2 Whitney, Megan R.; Sidor, Christian A. (2016). "A new therapsid from the Permian Madumabisa Mudstone Formation (mid-Zambezi Basin) of southern Zambia". Journal of Vertebrate Paleontology. 36 (4): e1150767. Bibcode:2016JVPal..36E0767W. doi:10.1080/02724634.2016.1150767. S2CID   130695355.
  2. 1 2 3 4 5 Angielczyk, Kenneth D.; Kammerer, Christian F. (2018). "Non-Mammalian synapsids: the deep roots of the mammalian family tree". In Zachos, Frank E.; Asher, Robert J. (eds.). Mammalian Evolution, Diversity and Systematics. Berlin: De Gruyter. ISBN   9783110275902.
  3. Kruger, A., B. S. Rubidge, F. Abdala, E. Gomani Chindebvu, L. L. Jacobs (2015). "Lende chiweta, a new therapsid from Malawi, and its influence on burnetiamorph phylogeny and biogeography". Journal of Vertebrate Paleontology. 35 (6): e1008698. Bibcode:2015JVPal..35E8698K. doi:10.1080/02724634.2015.1008698. S2CID   83725100.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. Sidor, C. A., K. D. Angielczyk, D. M. Weide, R. M. H. Smith, S. J. Nesbitt, L. A. Tsuji (2010). "Tetrapod Fauna of the Lowermost Usili Formation (Songea Group, Ruhuhu Basin) of Southern Tanzania, with a New Burnetiid Record". Journal of Vertebrate Paleontology. 30 (3): 696-703. Bibcode:2010JVPal..30..696S. doi:10.1080/02724631003758086. JSTOR   40666190. S2CID   55397720.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. Sidor, C. A., K. D. Angielczyk, R. M. H. Smith, A. K. Goulding, S. J. Nesbitt, B. R. Peecook, J. S. Steyer, S. Tolan (2014). "Tapinocephalids (Therapsida, Dinocephalia) from the Permian Madumabisa Mudstone Formation (Lower Karoo, Mid-Zambezi Basin) of southern Zambia". Journal of Vertebrate Paleontology. 34 (4): 980–986. Bibcode:2014JVPal..34..980S. doi:10.1080/02724634.2013.826669. S2CID   128431441.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. Day, Michael O.; Smith, Roger M. H.; Benoit, Julien; Fernandez, Vincent; Rubidge, Bruce S. (2018). "A new species of burnetiid (Therapsida, Burnetiamorpha) from the early Wuchiapingian of South Africa and implications for the evolutionary ecology of the family Burnetiidae". Papers in Palaeontology. 4 (3): 453–475. Bibcode:2018PPal....4..453D. doi:10.1002/spp2.1114. S2CID   90992821.
  7. Hopson, J.A. and H.R. Barghusen. 1986. "An analysis of therapsid relationships". In: The Ecology and Biology of Mammal-like reptiles (eds. by N. Hotton III, P.D. MacLean, J.J. Roth, & E.C. Roth) pp. 83-106. Washington, DC: Smithsonian Institution Press
  8. "Classification of the vertebrates". Palaeo.gly. Archived from the original on 2008-10-19.
  9. Sidor, C.A.; Smith, R.M.H. (2007). "A second burnetiamorph therapsid from the Permian Teekloof Formation of South Africa and its associated fauna". Journal of Vertebrate Paleontology. 27 (2): 420–430. doi:10.1671/0272-4634(2007)27[420:ASBTFT]2.0.CO;2. S2CID   86173425.

Further reading