Open Paleo

Itapeuasaurus

Lindoso et al., 2019

Named for Itapeua, the beach locality in Maranhão, Brazil where the fossils were discovered, combined with Greek 'sauros' meaning 'lizard', hence 'Itapeua lizard'.

100.5–93.9 million years ago Cenomanian, Late Cretaceous
Late Cretaceous stages

Itapeuasaurus is a genus of rebbachisaurid sauropod dinosaur from the Alcântara Formation (Itapecuru Group) of Maranhão in Brazil. The type and only species is Itapeuasaurus cajapioensis. It is the most complete Cenomanian-aged diplodocoid known from South America and it is also the first reported Cenomanian-aged rebbachisaurid discovered in South America.

Under dispute

The describers placed Itapeuasaurus within Rebbachisaurinae as the sister taxon to Demandasaurus (Lindoso and colleagues, 2019). More recent analyses instead recover it in a more stemward position, outside Khebbashia, in a clade with the South American rebbachisaurids Sidersaura and Astigmasaura (Lerzo and colleagues, 2025; Bellardini and colleagues, 2025).

Diagnosis

  1. Large and deep fossae on ventro-lateral aspect of dorsal neural arch split by obliquely oriented laminae
  2. Posterior centrodiapophyseal lamina forked ventrally forming dorsal edge of centrodiapophyseal fossa
  3. Dorsal and ventral components of anterior caudal transverse process thinner than usual bony bar with prezygapophyseal centrodiapophyseal fossa lamina and prezygodiapophyseal centrodiapophyseal fossa accessory lamina
  4. Three shallow pneumatic fossae disposed vertically on dorsal surface of neural arch separated by spinoprezygapophysial lamina and spinopostzygapophysial accessory lamina
  5. Presence and symmetrical arrangement of prezygapophysial centrodiapophysial fossa lamina and prezygodiapophysial centrodiapophysial fossa accessory lamina in anterior caudal vertebrae

Species

Itapeuasaurus cajapioensis Lindoso et al., 2019

Type species

Named for Cajapió, the municipality in Maranhão, Brazil, near where the holotype was discovered.

Holotype
UFMA 1.10.1960-1 , Universidade Federal do Maranhão (UFMA), Campus do Bacanga
Material
Partial skeleton.
Horizon
Alcântara Formation, Cenomanian, Late Cretaceous , 100.5–93.9 million years ago
Locality
Itapeua beach, Maranhão, Brazil

References

  1. Lindoso, R. M.; Medeiros, M. A. A.; Carvalho, I. de S.; Pereira, A. A.; Mendes, I. D.; Iori, F. V.; Sousa, E. P.; Arcanjo, S. H. S.; Silva, T. C. M. (2019). A new rebbachisaurid (Sauropoda: Diplodocoidea) from the middle Cretaceous of northern Brazil. Cretaceous Research 104. Elsevier BV. doi:10.1016/j.cretres.2019.104191 lindoso2019a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates.

    jones2026b
  3. Bellardini, F.; Filippi, L. S.; Carballido, J. L.; Garrido, A. C.; Baiano, M. A. (2025). Side by side with titans: A new rebbachisaurid dinosaur from the Huincul Formation (upper Cenomanian) of Patagonia, Argentina. Cretaceous Research 176. Elsevier BV. doi:10.1016/j.cretres.2025.106188

    Recovered Itapeuasaurus stemward outside Khebbashia in a clade with Astigmasaura and Sidersaura.

    bellardini2025a
  4. Lerzo, L. N.; Gallina, P. A.; Canale, J. I.; Otero, A.; Carballido, J. L.; Apesteguía, S.; Makovicky, P. J. (2025). The last of the oldies: a basal rebbachisaurid (Sauropoda, Diplodocoidea) from the early Late Cretaceous (Cenomanian-Turonian) of Patagonia, Argentina. Historical Biology 37(2): 208-233. Informa UK Limited. doi:10.1080/08912963.2023.2297914

    Recovered Itapeuasaurus stemward outside Khebbashia, sister to Sidersaura.

    lerzo2025a
  5. Medeiros, M. A.; Arcanjo, S. H.; Carvalho, I. de S.; Pereira, A. A.; Lindoso, R. M.; Mendes, I. D.; Sousa, E. P.; Costa Filho, J. F.; Siqueira, W. da S. (2015). Nova ocorrência de Diplodocoidea na Bacia de São Luís (Cretáceo, Cenomaniano), norte do Maranhão. Anais do 14º Simpósio de Geologia da Amazônia 565-568. Sociedade Brasileira de Geologia.

    Reports the Itapeua beach site before the taxon was named, and is the source Lindoso and colleagues cite for it. Gives the beds as the Alcântara Formation or Alcântara Member of the Itapecuru.

    medeiros2015a