Biarmosuchia

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Biarmosuchia
Temporal range:
Ma
Mounted skeleton of
Biarmosuchus tener
Scientific classification Edit this classification
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

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.

Characteristics

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

The biarmosuchian

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

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:

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.

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

References

  1. ^ a b 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.
    S2CID 130695355
    .
  2. ^ a b c d e 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. S2CID 83725100.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  4. S2CID 55397720.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  5. 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.
    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.
    S2CID 86173425
    .

Further reading

External links

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