Open Paleo

Dasosaurus

Mayer et al., 2026 DAH-so-SAWR-us

From Greek 'dasos' (forest, copse) and 'sauros' (lizard); meaning 'forest lizard', referring to the densely-vegetated dig site within Brazil's Legal Amazonia.

121.4–113.2 million years ago Aptian, Early Cretaceous
Early Cretaceous stages

Dasosaurus is an extinct genus of somphospondylan sauropod dinosaur known from the Early Cretaceous (Aptian) Itapecuru Formation of Maranhão, Brazil. The single species, Dasosaurus tocantinensis, is recovered as sister to the Spanish Barremian taxon Garumbatitan within a non-titanosaur Somphospondyli clade, and is among the largest known Brazilian sauropods at an estimated 18–22 m in length.

Diagnosis

  1. Anterior caudal neural spines expanded dorsolaterally ('stake-like' shaped), creating a quadrangular dorsal platform.
  2. Anterior surface of the femur lacks a linea intermuscularis cranialis.
  3. Pedal ungual phalanges I–II bear a distinct dorsolateral extensor tubercle extending ventrally along the lateroventral surface of the bone.
  4. Dorsal-most of the three neural arch pedicel ridges on middle-posterior caudal vertebrae positioned at the level of the dorsal margin of the prezygapophysis, dorsally bounding a shallower, ellipsoid costovertebral concavity.
  5. Femoral shaft more slender and more medially curved, with a lateral bulge corresponding to approximately 40% of the transverse minimal shaft width.

Species

Dasosaurus tocantinensis Mayer et al., 2026

Type species

Named for the Tocantins River, on whose eastern banks the holotype was collected in Maranhão state, Brazil.

Holotype
CPHNAM VT 1600 , Centro de Pesquisas de História Natural e Arqueologia do Maranhão
Material
Partial postcranial skeleton: caudal vertebrae and chevrons, left radius and ulna, partial right manus, distal left pubis, left ischium, right femur, proximal left tibia and fibula, distal right fibula, partial left pes, and trunk rib fragments.
Horizon
lower Itapecuru Formation, Aptian, Early Cretaceous , 121.4–113.2 million years ago
Locality
Davinópolis, Maranhão, Brazil

References

  1. Mayer, E. L.; Silva Junior, J. C. G.; Kerber, L.; Navarro, B. A.; Bandeira, K. L. N.; Cisneros, J. C.; Sousa, E. P.; Pereira, A. A.; Medeiros, M. A.; Lindoso, R. M.; Cavalcanti Neto, F. P.; Ghilardi, A. M.; Aureliano, T.; Godoy, P. L.; Ferreira, G. S.; Langer, M. C. (2026). A new titanosauriform with European affinities in the Early Cretaceous of Brazil: insights on Somphospondyli phylogeny, histology and biogeography. Journal of Systematic Palaeontology 24: 2601579. Taylor & Francis. doi:10.1080/14772019.2025.2601579 mayer2026a