Open Paleo

Secernosaurus

Brett-Surman, 1979 see-SER-no-SAWR-us

From Latin 'secerno' meaning 'to separate' or 'sever' and Greek 'sauros' meaning 'lizard'; meaning 'severed lizard', referring to its geographic separation from other hadrosaurs in South America.

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

Secernosaurus is a genus of herbivorous hadrosaurid dinosaur that lived during the Late Cretaceous of what is now Argentina. This genus and its close relatives lived in South America, unlike most hadrosaurids, which lived in the Laurasian continents of Eurasia and North America. It has been suggested that the ancestors of Secernosaurus crossed into South America when a land bridge temporarily formed between North and South America during the Late Cretaceous and allowed biotic interchange between the two continents.

Diagnosis

  1. Postacetabular process of ilium greatly deflected dorsomedially and elongate, unlike any hadrosaurian or iguanodont
  2. Preacetabular process of ilium deflected ventrally at an angle greater than in Hadrosaurus
  3. Antitrochanter relatively smaller than in any hadrosaurian of the same size

Species

Secernosaurus koerneri Brett-Surman, 1979

Type species

Named for Harold E. Koerner.

Holotype
FMNH P13423 , Field Museum of Natural History
Material
Two ilia, prepubis, scapula, fibula, caudals, partial braincase
Horizon
Lago Colhué Huapi Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
Río Chico, Chubut, Argentina

References

  1. Brett-Surman, M. K. (1979). Phylogeny and palaeobiogeography of hadrosaurian dinosaurs. Nature 277(5697): 560-562. Springer Science and Business Media LLC. doi:10.1038/277560a0 brett-surman1979a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the mass and hip height estimates.

    jones2026a
  3. Casal, G. A.; Allard, J. O.; Foix, N. (2015). Análisis estratigráfico y paleontológico de afloramientos del Cretácico Superior en la cuenca del Golfo San Jorge: propuesta de nueva unidad litoestratigráfica para el Grupo Chubut. Revista de la Asociación Geológica Argentina 72(1): 81-99.

    Erects the Lago Colhué Huapi Formation for the headwaters-of-the-Río-Chico strata that produced the holotype, and places the site about 4 km from the mouth of the Río Chico.

    casal2015a