Open Paleo

Trigonosaurus

Campos et al., 2005 try-GON-o-SAWR-us Disputed

From Greek 'trigōnon' (triangle), in reference to the Triângulo Mineiro region of Minas Gerais, Brazil where the holotype was found, and 'sauros' (lizard); meaning 'triangle lizard'.

72.2–66.0 million years ago Maastrichtian, Late Cretaceous
Late Cretaceous stages

Trigonosaurus is a genus of titanosaurian dinosaurs from the Maastrichtian Serra da Galga Formation of Brazil. The type species, Trigonosaurus pricei, was first described by Campos, Kellner, Bertini, and Santucci in 2005. It was based on two specimens, both consisting mainly of vertebrae. The two specimens were originally believed to have come from the same individual. However, one specimen was described as the holotype of Caieiria in 2022, while the holotype may have instead come from Baurutitan. Before its description, it was known as the "Peirópolis titanosaur", after the place it was found.

Under dispute

The validity of Trigonosaurus is contested. Silva Junior and colleagues (2022) proposed that T. pricei is a junior subjective synonym of Baurutitan britoi (which has page priority within the same 2005 journal volume) and erected the postcranial paratype (MCT 1719-R) as a separate new genus, Caieiria allocaudata. Fronimos (2023) explicitly rejected the synonymy, citing morphological differences in the first caudal vertebra of the two taxa.

Diagnosis

  1. Midcervical vertebrae elongated, with low neural spine and concave ventral margin of centrum.
  2. Middorsal vertebrae elongated, with neural spine strongly inclined posteriorly.
  3. Dorsal vertebrae 9 and 10 bear an incipient postzygodiapophyseal lamina linking diapophysis and postzygapophysis.
  4. Anterior caudal vertebrae (2-5) with two pronounced dorsal depressions on the transverse process; middle caudals with one such depression.
  5. Prezygapophyses on caudal vertebrae extended forward with wide articular faces.
  6. Articular surfaces for haemal arches strongly developed from caudal 3 through the last preserved element (caudal 20); transverse processes well developed throughout the anterior and medial caudal sequence.

Species

Trigonosaurus pricei Campos et al., 2005 Disputed

Type species

Named in honor of Brazilian vertebrate paleontologist Llewellyn Ivor Price (1905-1980), whose birth centenary was celebrated in 2005.

Holotype
MCT 1488-R , Museu da Divisão de Geologia e Mineralogia
Material
Articulated partial vertebral column: five posterior cervical vertebrae (cervicals 9-13), ten dorsal vertebrae, six sacral vertebrae, and the left ilium.
Horizon
Serra da Galga Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
Caieira, Minas Gerais, Brazil

References

  1. Campos, D. A.; Kellner, A. W. A.; Bertini, R. J.; Santucci, R. M. (2005). On a titanosaurid (Dinosauria, Sauropoda) vertebral column from the Bauru Group, Late Cretaceous of Brazil. Arquivos do Museu Nacional, Rio de Janeiro 63(3): 565-593. campos2005a
  2. Silva Junior, J. C. G.; Martinelli, A. G.; Marinho, T. S.; da Silva, J. I.; Langer, M. C. (2022). New specimens of Baurutitan britoi and a taxonomic reassessment of the titanosaur dinosaur fauna (Sauropoda) from the Serra da Galga Formation (Late Cretaceous) of Brazil. PeerJ 10: e14333. PeerJ. doi:10.7717/peerj.14333

    Synonymizes T. pricei with Baurutitan britoi (page priority within the same 2005 journal volume) and erects the postcranial paratype (MCT 1719-R) as the new genus Caieiria allocaudata.

    silvajunior2022a
  3. Fronimos, J. A. (2023). Patterns and function of pneumaticity in the vertebrae, ribs, and ilium of a titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Texas. Journal of Vertebrate Paleontology 43(2): e2259444. doi:10.1080/02724634.2023.2259444

    Texas titanosaur pneumaticity study rejecting the Silva Junior and colleagues (2022) synonymy of Trigonosaurus into Baurutitan, on differences in the first caudal vertebra.

    fronimos2023a
  4. Soares, M. V. T.; Basilici, G.; Marinho, T. S.; Martinelli, A. G.; Marconato, A.; Mountney, N. P.; Colombera, L.; Mesquita, Á. F.; Vasques, J. T.; Abrantes Junior, F. R.; Ribeiro, L. C. B. (2020). Sedimentology of a distributive fluvial system: the Serra da Galga Formation, a new lithostratigraphic unit (Upper Cretaceous, Bauru Basin, Brazil). Geological Journal 56(2): 951-975. Wiley. doi:10.1002/gj.3987

    Prints the Price 1 Geosite, "also known in the literature as 'Caieira Site' or 'Ponto 1 do Price'", at 19°43′26.89″S, 47°44′47.45″W.

    soares2020a