Titanophoneus

Titanophoneus ("titanic murderer") is an extinct genus of carnivorous dinocephalian therapsid from the Middle Permian. It is classified within the family Anteosauridae. The type species is Titanophoneus potens.^[1] Remains of Titanophoneus have been found at Isheevo, Russia. It was one of the last anteosaurs in Eastern Europe, as the clade was absent in the following Sundyr Assemblage, being replaced by large therocephalians.^[2][3][4]

Classification

Titanophoneus potens was named by Efremov in 1938 and was briefly described based on two skulls and associated postcrania. Despite the difference sizes of the skulls, he considered them to be members of the same species.^[1]

Initially, it has been hypothesized by experts that estemmenosuchids were the most basal of the dinocephalians,^[5][6] however more recent analysis have instead recovered anteosaurs as the basal dinocephalians.^[7][8][1]

Kamerrer (2011) performed the first phylogenetic analysis which included all anteosaurid taxa. Along with other subsequent phylogenetic analysis of anteosaurs, this study recovered a monophyletic Anteosauridae containing two major clades, Syodontinae and Anteosaurinae: in Kammerer's analysis, the Chinese Sinophoneus is the most basal anteosaurine and the sister group of an unresolved trichotomy including T. potens, T. adamanteus, and Anteosaurus. The following cladogram is based on Kammerer (2011):^[1]Following the discovery of the Brazilian anteosaur Pampaphoneus, Cisneros et al. presented another cladogram confirming the recognition of Syodontinae and Anteosaurinae. In the Fig. 2. cladogram of the main paper (which does not include Microsyodon), T. adamanteus is recovered as the sister taxon of a clade composed of T. potens and Anteosaurus. However, in the four cladograms within the supplementary material/supporting information of this paper, (which included Microsyodon), Anteosaurus is recovered as the sister taxon of both species of Titanophoneus. These four cladograms differ only by the position of Microsyodon within the matrix.^[9]

The following cladograms are those from Cisneros et al. (2012); the first is from the main article, which excludes the genus Microsyodon:In resdescribing the Chinese anteosaur Sinophoneus, Jun Lui presented a new cladogram in which Sinophoneus is recovered as the most basal Anteosauridae and so excluded from Anteosaurinae. Here Anteosaurus is the sister-taxon of T. potens and T. adamanteus. The following cladogram is based on Jun Liu (2013):^[10]

Description

An adult skull would have reached 80 cm (31 in) with a heavy long snout and was estimated to have measured 6 m (20 ft) in length.^[11] The long tail and short limbs show the species to be a primitive therapsid, unlike Inostrancevia, which was more advanced. The structure of the limbs and the density of the bone are designed for a sprawling stance. The temporal opening is more advanced than Estemmenosuchidae, but less advanced than Inostrancevia.

The teeth are large with 12 large palate incisors followed by 2 canines and various smaller back teeth. The lower palate is the same as the upper but without the canine teeth. The appearance of Titanophoneus is reminiscent to the sphenacodontid pelycosaurs, which included Dimetrodon.

See also

• List of therapsids

References

1. ^ Kammerer, C.F. (2011). "Systematics of the Anteosauria (Therapsida: Dinocephalia)". Journal of Systematic Palaeontology. 9 (2). doi:10.1080/14772019.2010.492645
2. ^ Suchkova, J. A. & Golubev, V. K. (2019). "A new primitive therocephalian (Theromorpha) from the Middle Permian of Eastern Europe". Paleontological Journal. 53 (3): 305–314. doi:10.1134/S0031030119030158
3. ^ Suchkova, J.A. & Golubev, V.K. (2019). "New Permian therocephalian (Therocephalia, Theromorpha) from the Sundyr Assemblage of Eastern Europe". Paleontological Journal. ' (4): 87–92. doi:10.1134/S0031031X19040123
4. ^ Sennikov, A. G. & Golubev, V. K. (2017). "Sequence of Permian tetrapod faunas of Eastern Europe and the Permian–Triassic ecological crisis". Paleontological Journal. 51 (6): 600-611. doi:10.1134/S0031030117060077
5. ^ Kemp, T. S. (1982). Mammal-like Reptiles and the Origin of Mammals. New York: Academic Press. pp. 363pp.
6. ^ King, G. M. (1988). "Anomodontia". Encyclopedia of Paleoherpetology. Vol. Part 17 C. Stuttgart and New York: Gutsav Fischer Verlag.
7. ^ Rubidge, Bruce S. & Sidor, Christian A. (2001). "Evolutionary Patterns Among Permo-Triassic Therapsids". Annual Review of Ecology and Systematics. 32: 449-480.
8. ^ Bhat, M. S.; Shelton, C.; Chinsamy-Turan, A. (2021). "Bone histology of dinocephalians (Therapsida, Dinocephalia): palaeobiological and palaeoecological inferences". Papers in Palaeontology. 8. doi:10.1002/spp2.1411
9. ^ Cisneros, J.C.; Abdala, Fernando; Atayman-Güven, S.; Rubidge, Bruce S.; Şengör, A. M. C.; Schultz, C. L. (2012). "Carnivorous dinocephalian from the Middle Permian of Brazil and tetrapod dispersal in Pangaea". Proceedings of the National Academy of Sciences of the United States of America. 109 (5): 1584–1588. Bibcode:2012PNAS..109.1584C. doi:10.1073/pnas.1115975109. PMC 3277192. PMID 22307615
10. ^ Liu, J. (2013). "Osteology, Ontogeny, and Phylogenetic Position of Sinophoneus yumenensis (Therapsida, Dinocephalia) from the Middle Permian Dashankou Fauna of China". Journal of Vertebrate Paleontology. 33 (6): 1394–1407. Bibcode:2013JVPal..33.1394L. doi:10.1080/02724634.2013.781505. S2CID 85577626
11. ^ Cisneros, J.C.; Abdala, F.; Atayman-Güven, S.; Rubidge, B.S.; Şengör, A.M.C.; Schultz, C.L. (2012). "Carnivorous dinocephalian from the Middle Permian of Brazil and tetrapod dispersal in Pangaea". Proceedings of the National Academy of Sciences of the United States of America. 109 (5): 1584–1588. Bibcode:2012PNAS..109.1584C. doi:10.1073/pnas.1115975109. PMC 3277192. PMID 22307615

• Vickers-Rich, Patricia & Thomas H. Rich (1993). The Great Russian Dinosaurs. Guntar Graphics. p. 36.

External links

• Taxonomy