Venyukoviamorpha

Venyukoviamorpha Temporal range: Middle Permian - Late Permian
Scientific classification
Kingdom:	Animalia
Division:	Synapsida
Phylum:	Chordata
Superorder:	†Venyukovioidea
Order:	†Therapsida
Suborder:	†Anomodontia
Superfamily:	†Venyukoviamorpha
Family:	†Venyukoviidae
Binomial name
Venyukoviamorpha D. M. S. Watson and Alfred Romer, 1956

Venyukoviamorpha is an extinct superfamily of anomodont therapsids under the superorder Venyukovoidea. While the exact placement of many genera within the basal anomodonts is contentious, it is generally accepted that the Venyukoviamorpha represent a monophyletic clade.^[1]

Four genera of small, plant-eating anomodonts make up the Venyukoviamorpha -- Venyukovia, Ulemica, Otsheria, and Suminia. All Venyukoviamorpha remains have been found in western Siberia (located during the Middle to Late Permian in Laurasia, the northern part of the supercontinent Pangea).

The Venyukoviamorpha were named for Venyukovia (in turn, named for that fossil's discoverer, Russian geologist P.N. Venyukov).^[2] But Venyukovia is known only from lower jaw fragments of a single individual (other fossil remains originally attributed to Venyukovia having been reassigned to the later genus, Ulemia).^[3] Ulemia ^[4] and the poorly preserved Otsheria ^[5] also lack post-cranial remains.

To date, the only preserved Venyukoviamorpha post-cranial remains are associated with the later Suminia fossil. Suminia is described as a derived venyukovioid and a sister-taxon of Ulemica.^[6] A Suminia fossil (PIN 2212/116) revealed a long-tailed animal by therapsid standards. The comparatively long limbs and phalanges with opposable 'thumbs' led to the suggestion that Suminia was adapted for grasping tree branches in an arboreal lifestyle.^[7]

Compared with other therapsids, the Venyukoviamorpha were distinguished by comparatively long tooth rows with large incisors.^[8] The arrangement of teeth was complex and varied greatly among members of the Venyukoviamorpha.^[9] Incisors were chisel-shaped ^[10] or leaf-shaped and serrated.^[11] Post-canine teeth could be spatulate (Otsheria), bluntly conical (Venyukovia) for grinding, or leaf-shaped for shredding (Suminia).^[12] The mixed dentition of Suminia is claimed to represent the first evidence of the efficient processing of food by chewing.^[13]

The Venyukoviamorpha lived in environments surrounded by amphibians, pareiasaurs and other reptiles, as well as other therapsids. As an example, small plant-eating Otsheria existed alongside larger therapsid herbivores (Estemmenosuchus) and therapsid hunters (biarmosuchians, anteosaurid dinocephalians, and gorgonopsians).^[14]

References

1. Benton, M.J., Shishkin, M.A., and Unwin, D.M., eds. (2000), The Age of Dinosaurs in Russia and Mongolia, Cambridge University Press , 105 ISBN 978-0-521-54582-2.
2. Benton, M.J., Shishkin, M.A., and Unwin, D.M., eds. (2000), The Age of Dinosaurs in Russia and Mongolia, Cambridge University Press , 23-24, ISBN 978-0-521-54582-2.
3. Benton, M.J., Shishkin, M.A., and Unwin, D.M., eds. (2000), The Age of Dinosaurs in Russia and Mongolia, Cambridge University Press, 105 ISBN 978-0-521-54582-2, and Ivakhnenko, M. F. (1996). "Primitive anomodonts, venyukoviids, from the Late Permian of Eastern Europe". Paleontological Journal 30: 575–582.
4. Fröbisch, Jörg and Reisz, Robert R. (2011), The postcranial anatomy of Suminia getmanovi (Synapsida: Anomodontia), the earliest known arboreal tetrapod, Zoological Journal of the Linnean Society, 162: 662.
5. Angielczyk, Kenneth D. (2004), Phylogenetic evidence for and implications of a dual origin of propaliny in anomodont therapsids (Synapsida), Paleobiology, 30: 268–296.
6. Rybczynski, Natalia (2000), "Cranial anatomy and phylogenetic position of Suminia getmanovi, a basal anomodont (Amniota: Therapsida) from the Late Permian of Eastern Europe," Zoological Journal of the Linnean Society 130 (3): 329–373.
7. Fröbisch, Jörg and Reisz, Robert R. (2009), "The Late Permian herbivore Suminia and the early evolution of arboreality in terrestrial vertebrate ecosystems," Proceedings of the Royal Society, Biological Sciences, 276: 3611–3618.
8. Boonstra, L. D. (1971), "The early therapsids", Annals of the South African Museum, 59: (November 1972, paper first published in December 1971) http://archive.org/stream/annalsofsouth59197172sout/annalsofsouth59197172sout_djvu.txt
9. Kemp, Tom S. (2005), The Origin and Evolution of Mammals, Oxford University Press, 39-42, ISBN 978-0-19-850761-1.
10. Benton, M.J., Shishkin, M.A., and Unwin, D.M., eds. (2000), The Age of Dinosaurs in Russia and Mongolia, Cambridge University Press , 105, ISBN 978-0-521-54582-2.
11. Cisneros, Juan Carlos, et al (2011), "Dental Occlusion in a 260-Million-Year-Old Therapsid with SaberCanines from the Permian of Brazil," Science, 331: 1603.
12. Rybczynski, Natalia (2000), "Cranial anatomy and phylogenetic position of Suminia getmanovi, a basal anomodont (Amniota: Therapsida) from the Late Permian of Eastern Europe," Zoological Journal of the Linnean Society, 130 (3): 329–373.
13. Rybczynski, Natalia and Reisz, Robert R. (2001), "Earliest evidence for efficient oral processing in a terrestrial herbivore," Nature 411: 684–687.
14. Kemp, Tom S. (2006), "The origin and early radiation of the therapsid mammal-like reptiles: a palaeobiological hypothesis," Journal of Evolutionary Biology, 19 (4): 1231–1247.