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Dinocephalia

From Wikipedia, the free encyclopedia
For other uses, see Dinocephalia (disambiguation).

Dinocephalia
Temporal range: Guadalupian (Middle Permian) 274.4–260 Ma
Restoration of two genera of dinocephalians : Titanophoneus (an anteosaur) devouring a Ulemosaurus (a tapinocephalian).
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Suborder: †Dinocephalia
Seeley, 1894
Subgroups

See Taxonomy

Dinocephalia is a clade of generally large-bodied therapsids that flourished during Middle Permian between approximately 275 and 260 million years ago (Ma),[1][2][3] but became extinct during the Capitanian mass extinction event. Dinocephalians included herbivorous, carnivorous, and omnivorous forms.[4] Many species had thickened skulls with many knobs and bony projections. Dinocephalians were the first non-mammalian therapsids to be scientifically described[5] and their fossils are known from Russia, China, Brazil, South Africa, Zimbabwe, and Tanzania.[6][7]

Description

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They include carnivorous, herbivorous, and omnivorous forms. It has been disputed as to whether some dinocephalians were semi-aquatic like hippopotamuses.[8]

Size

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Size of various individuals of the large carnivorous dinocephalian Anteosaurus compared to a human
Size of the herbivorous or omnivorous dinocephalian Jonkeria compared to a human

Dinocephalians were generally large in size,[1] and some the largest animals of the Permian period, and the first synapsids to reach a body size around one tonne.[9] The herbivorous or omnivorous Jonkeria has been suggested to have weighed 989 kilograms (2,180 lb), while the large carnivore Anteosaurus has been estimated to weigh 400 kilograms (880 lb) based on scaled 3D models.[10]

Skull and jaws

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Cranial ornamentation in dinocephalians
Skull of Titanophoneus (Anteosauria)
Skull of Moschops (Tapinocephalidae)
Skull of Estemmenosuchus

The temporal fenestra at the back of the skull is relatively enlarged in dinocephalians,[11]11 with the quadrate and quadratojugal bones at the back of the skull also being enlarged.[11]38 All dinocephalians are characterised by the interlocking incisor (front) teeth, though this was formerly thought to be unique to the group, it is also found in biarmosuchians.[12] Correlated features are the distinctly downturned facial region, a deep temporal region, and forwardly rotated suspensorium. Shearing contact between the upper and lower teeth (allowing food to be more easily sliced into small bits for digestion) is achieved through keeping a fixed quadrate and a hinge-like movement at the jaw articulation. The lower teeth are inclined forward, and occlusion is achieved by the interlocking of the incisors. The later dinocephalians improved on this system by developing heels on the lingual sides of the incisor teeth that met against one another to form a crushing surface when the jaws were shut.[citation needed]

Suggested intraspecific combat styles in dinocephalians. 1/top left: Face biting (Anteosauria), 2/top centre: head-butting (Tapinocephalidae e.g. Moschops), 3/ left: flank butting (Styracocephalus) 4/bottom left: locking and pushing (Estemmenosuchus) 5. bottom centre: stabbing (Struthiocephalus)

Most dinocephalians also developed a thickened (pachyostotic) and ornamented skull roof and braincase of varying and diverse form, sometimes with horn-like projections.[1] It has been widely suggested that tapinocephalids engaged in head-butting.[1] Other dinocephalians may have engaged in biting or head interlocking combat against rival individuals.[13]

The coronoid bones and the corresponding coronoid process on the lower jaw were lost in dinocephalians.[11]11,38

Limbs

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Dinocephalian limb bones are generally optimised for muscle strength. Dinocephalians are likely to have had a sprawling posture,[14] or a posture intermediate between sprawling and upright.[9]

Evolutionary history

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Dinocephalians first appeared during the early Roadian as evidence by remains found in Russia, but their geographic origin and early evolution like that of other therapsids in general is not clear.[15][16]

Phylogeny of Dinocephalia following Fraser-King et al. 2019[17]

During the Wordian and early Capitanian, advanced dinocephalians radiated into a large number of herbivorous forms, representing a diverse megafauna. This is well known from the Tapinocephalus Assemblage Zone of the Southern African Karoo.

At the height of their diversity (middle or late Capitanian age) all the dinocephalians suddenly died out, during the Capitanian mass extinction event. The reason for their extinction is not clear; although disease, sudden climatic change, or other factors of environmental stress may have brought about their end. They were replaced by much smaller therapsids; herbivorous dicynodonts and carnivorous biarmosuchians, gorgonopsians and therocephalians.

Taxonomy

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Estemmenosuchus, an estemmenosuchid
Anteosaurus, an anteosaur
Ulemosaurus, a tapinocephalian

See also

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References

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  1. ^ a b c d Benoit, Julien; Manger, Paul R.; Norton, Luke; Fernandez, Vincent; Rubidge, Bruce S. (2017-08-10). "Synchrotron scanning reveals the palaeoneurology of the head-butting Moschops capensis (Therapsida, Dinocephalia)". PeerJ. 5 e3496. doi:10.7717/peerj.3496. ISSN 2167-8359. PMC 5554600. PMID 28828230.
  2. ^ Day, Michael O.; Guven, Saniye; Abdala, Fernando; Jirah, Sifelani; Rubidge, Bruce; Almond, John (2015). "Youngest dinocephalian fossils extend the Tapinocephalus Zone, Karoo Basin, South Africa". South African Journal of Science. 111 (3/4): 1–5. Bibcode:2015SAJSc.111....1D. doi:10.17159/sajs.2015/20140309.
  3. ^ "Driveria". Fossilworks.
  4. ^ Nicolas, Merrill; Rubidge, Bruce S. (2010). "Changes in Permo-Triassic terrestrial tetrapod ecological representation in the Beaufort Group (Karoo Supergroup) of South Africa". Lethaia. 43 (1): 45–59. Bibcode:2010Letha..43...45N. doi:10.1111/j.1502-3931.2009.00171.x.
  5. ^ Kammerer, Christian F. (13 December 2010). "Systematics of the Anteosauria (Therapsida: Dinocephalia)". Journal of Systematic Palaeontology. 9 (2): 261–304. doi:10.1080/14772019.2010.492645.
  6. ^ Angielczyk, K.D. (2009). "Dimetrodon is not a dinosaur: Using tree thinking to understand the ancient relatives of mammals and their evolution". Evolution: Education and Outreach. 2 (2): 257–271. doi:10.1007/s12052-009-0117-4.
  7. ^ Simon, Rachel V.; Sidor, Christian A.; Angielczyk, Kenneth D.; Smith, Roger M.H. (2010). "First record of a Tempinocephalid (Therapsida: Dinocephalia) from the Ruhuhu Formation (Songea Group) of Southern Tanzania". Journal of Vertebrate Paleontology. 30 (4): 1289–1293. Bibcode:2010JVPal..30.1289S. doi:10.1080/02724634.2010.483549. S2CID 131447562.
  8. ^ Mohd Shafi Bhat, Christen D. Shelton, Anusuya Chinsamy (2021). "Bone histology of dinocephalians (Therapsida, Dinocephalia): palaeobiological and palaeoecological inferences". Papers in Palaeontology. 8 (1) e1411. doi:10.1002/spp2.1411.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ^ a b Romano, Marco; Rubidge, Bruce (2021-04-03). "First 3D reconstruction and volumetric body mass estimate of the tapinocephalid dinocephalian Tapinocaninus pamelae (Synapsida: Therapsida)". Historical Biology. 33 (4): 498–505. Bibcode:2021HBio...33..498R. doi:10.1080/08912963.2019.1640219. ISSN 0891-2963.
  10. ^ Benoit, Julien; Midzuk, A. J. (2024-08-09). "Estimating the endocranial volume and body mass of Anteosaurus, Jonkeria, and Moschops (Dinocephalia, Therapsida) using 3D sculpting". Palaeontologia Electronica. 27 (2): 1–11. doi:10.26879/1377. ISSN 1094-8074.
  11. ^ a b c KING, G.M. 1988. Anomodontia. In: Wellnhofer, P. (ed.), Encyclopedia of Paleoherpetology. 174 pp. Stuttgart, Gustav Fischer.
  12. ^ Lafferty, Tristen; Norton, Luke A.; Duhamel, Aliénor; Benoit, Julien (2025-09-08). "Description of the skull, braincase, and dentition of Moschognathus whaitsi (Dinocephalia, Tapinocephalia), and its palaeobiological and behavioral implications". The Anatomical Record ar.70038. doi:10.1002/ar.70038. ISSN 1932-8486. PMID 40922509.
  13. ^ Bolton, Andrew D.; Mangera, Taahirah; Benoit, Julien (2025-08-12). "150 years of synapsid paleoneurology: the origins of the mammalian brain, behavior, sense organs and physiology". Journal of Paleontology: 1–29. doi:10.1017/jpa.2025.10121. ISSN 0022-3360.
  14. ^ Brocklehurst, Robert J.; Mercado, Magdalen; Angielczyk, Kenneth D.; Pierce, Stephanie E. (2025-06-24). Quental, Tiago Bosisio (ed.). "Adaptive landscapes unveil the complex evolutionary path from sprawling to upright forelimb function and posture in mammals". PLOS Biology. 23 (6): e3003188. doi:10.1371/journal.pbio.3003188. ISSN 1545-7885. PMC 12186895. PMID 40554496.{{cite journal}}: CS1 maint: article number as page number (link)
  15. ^ Golubev, V. K. (December 2015). "Dinocephalian stage in the history of the Permian tetrapod fauna of Eastern Europe". Paleontological Journal. 49 (12): 1346–1352. Bibcode:2015PalJ...49.1346G. doi:10.1134/S0031030115120059. ISSN 0031-0301.
  16. ^ Duhamel, Alienor; Wynd, Brenen; Wright, April Marie; Moopen, Atashni; Benoit, Julien; Rubidge, Bruce (2026-03-11). "Rethinking therapsid phylogeny through Bayesian and cladistic approaches". Scientific Reports. 16 (1) 13171. Bibcode:2026NatSR..1613171D. doi:10.1038/s41598-026-38195-2. ISSN 2045-2322. PMC 13103076. PMID 41813723.
  17. ^ Fraser-King, Simon W.; Benoit, Julien; Day, Michael O.; Rubidge, Bruce S. (2019). "Cranial morphology and phylogenetic relationship of the enigmatic dinocephalian Styracocephalus platyrhynchus from the Karoo Supergroup, South Africa". Palaeontologia Africana. 54: 14–29.

Further reading

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  • Carroll, R.L. (1988). Vertebrate Paleontology and Evolution. W.H. Freeman.
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