Biology:Macrocephalosaurus

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Short description: Extinct genus of reptiles

Macrocephalosaurus
Temporal range: Late Triassic (Carnian), ~231–227 Ma
Scientific classification e
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
Tupi Caldas 1933
Species
  • M. mariensis Tupi Caldas, 1933 (type)

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]

Classification

The 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 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

Isalorhynchus genovefae Cartography of Africa.svg

Teyumbaita sulcognathus Cartography of South America.svg

Hyperodapedon

H. huenei Cartography of South America.svg

H. mariensis (Macrocephalosaurus)Cartography of South America.svg

H. sanjuanensis Cartography of South America.svg

H. sp from Wolfville (Oryctorhynchus) Cartography of North America.svg

H. sp from India Cartography of Asia.svg

H. huxleyi (Paradapedon) Cartography of Asia.svg

H. gordoni Cartography of Europe.svg

H. sp from Wyoming (Beesiiwo) Cartography of North America.svg

H. sp from Zimbabwe Cartography of Africa.svg

H. tikiensis Cartography of Asia.svg

Supradapedon stockleyi Cartography of Africa.svg

   Valid species that were first assigned to Scaphonyx.

The following cladogram is based on the phylogenetic analysis by Fitch et al. (2023):[1]

Isalorhynchus genovefae

Hyperodapedontinae

Beesiiwo cooowuse

Oryctorhynchus bairdi

Hyperodapedon gordoni

"Zimbabwe Form"

Paradapedon huxleyi

"Scaphonyx" sanjuanensis

Macrocephalosaurus mariensis

"Hyperodapedon" tikiensis

Supradapedon stockleyi

"Hyperodapedon" huenei

Teyumbaita sulcognathus

References

  1. 1.0 1.1 1.2 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. 
  2. 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.].
  3. 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.
  4. Langer, Max C.; Schultz, Cesar L. (2000). "A New Species Of The Late Triassic Rhynchosaur Hyperodapedon From The Santa Maria Formation Of South Brazil" (in en). Palaeontology 43 (4): 633–652. doi:10.1111/1475-4983.00143. ISSN 0031-0239. Bibcode2000Palgy..43..633L. https://www.paleolab.com.br/assets/uploads/files/pdf/Langer_Schultz_2000.pdf. 
  5. 5.0 5.1 Mukherjee, Debarati; Ray, Sanghamitra (2014). Benson, Roger. ed. "A new Hyperodapedon (Archosauromorpha, Rhynchosauria) from the Upper Triassic of India: implications for rhynchosaur phylogeny" (in en). Palaeontology 57 (6): 1241–1276. doi:10.1111/pala.12113. ISSN 0031-0239. Bibcode2014Palgy..57.1241M. https://onlinelibrary.wiley.com/doi/10.1111/pala.12113. 

External links

Wikidata ☰ Q134317 entry