Macrocephalosaurus is a genus of rhynchosaurs (beaked, archosaur-like reptiles) from the Late Triassic period (Carnian stage) of southern Brazil. It contains a single species, Macrocephalosaurus mariensis. Although usually synonymized with Hyperodapedon (as the species Hyperodapedon mariensis), some cladistic analyses have called this synonymy into question.[1]
| Macrocephalosaurus Temporal range: Late Triassic (Carnian), ~
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Archosauromorpha |
| Order: | †Rhynchosauria |
| Family: | †Rhynchosauridae |
| Subfamily: | †Hyperodapedontinae |
| Genus: | †Macrocephalosaurus Tupi Caldas, 1933 |
| Type species | |
| †Macrocephalosaurus mariensis | |
| Species | |
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Classification
editThe type species of Macrocephalosaurus, M. mariensis, was described in 1933 by Jaci Antonio Louzada Tupi Caldas on the basis of MCN 1867, a complete specimen from the upper member of the Santa Maria Formation in Rio Grande Do Sul State, southern Brazil. The skeleton was transferred to another museum in the mid-1950s, and as of 1998 only the skull and front part of the torso have been recovered; the rest of the skeleton is presumed lost. Langer (1996, 1998) regarded Macrocephalosaurus mariensis as a probable junior synonym of Hyperodapedon huxleyi, synonymizing Macrocephalosaurus with Hyperodapedon.[2][3]
Nevertheless, Langer and Schultz (2000) listed M. mariensis as a valid species within Hyperodapedon, as H. mariensis.[4] Mukherjee and Ray (2014) followed this interpretation.[5] In their cladistic analysis of the newly described taxon Beesiiwo, Fitch et al. (2023) recovered Macrocephalosaurus as more closely related to Supradapedon and Teyumbaita rather than Hyperodapedon gordoni (the type species of Hyperodapedon) or Oryctorhynchus. As a result, they recommended the revalidation of Macrocephalosaurus.[1]
The following cladogram is based on the phylogenetic analysis of Hyperodapedontinae by Mukherjee & Ray (2014):[5]
| Hyperodapedontinae |
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Valid species that were first assigned to Scaphonyx.
The following cladogram is based on the phylogenetic analysis by Fitch et al. (2023):[1]
References
edit- ^ a b c Fitch, Adam; Haas, Merle; C'Hair, Wayne; Ridgley, Eugene; Ridgley, Ben; Oldman, Devin; Reynolds, Crystal; Lovelace, David (10 April 2023). "A New Rhynchosaur Taxon from the Popo Agie Formation, WY: Implications for a Northern Pangean Early-Late Triassic (Carnian) Fauna". Diversity. 15 (4): 544. doi:10.3390/d15040544. hdl:10919/114487.
- ^ Langer, M.C. 1996. [Rincossaurossul-brasileiros histórico e filogenia. Dissertação de Maestrado, Instituto de Geociências, Universidad Federal do Rio Grande do Sul, Porto Alegre, 361 p. Unpublished.].
- ^ Langer, M.C. 1998. Gilmoreteiidae new family and Gilmoreteius new genus (Squamata, Scincomorpha): replacement names for Macrocephalosauridae Sulimski, 1975 and Macrocephalosaurus Gilmore, 1943. Comunicações do Museu de Ciências e Tecnologia da PUCRS, Série Zoologia Porto Alegre 11: 13–18.
- ^ Langer, Max C.; Schultz, Cesar L. (2000). "A New Species Of The Late Triassic Rhynchosaur Hyperodapedon From The Santa Maria Formation Of South Brazil" (PDF). Palaeontology. 43 (4): 633–652. Bibcode:2000Palgy..43..633L. doi:10.1111/1475-4983.00143. ISSN 0031-0239. S2CID 83566087.
- ^ a b Mukherjee, Debarati; Ray, Sanghamitra (2014). Benson, Roger (ed.). "A new Hyperodapedon (Archosauromorpha, Rhynchosauria) from the Upper Triassic of India: implications for rhynchosaur phylogeny". Palaeontology. 57 (6): 1241–1276. Bibcode:2014Palgy..57.1241M. doi:10.1111/pala.12113. ISSN 0031-0239.
