Open Paleo

Mesetasaurus

Soto Núñez et al., 2026

'Meseta', after the name of the locality (Meseta de Artigas), plus 'saurus', Greek for reptile.

89.8–66.0 million years ago Coniacian–Maastrichtian, Late Cretaceous
Late Cretaceous stages

Mesetasaurus is a genus of aeolosaurin titanosaurian sauropod dinosaurs known from the Guichón Formation (Late Cretaceous, potentially Coniacian to Maastrichtian) of Paysandú Department, Uruguay. The genus contains a single species, the type species Mesetasaurus protector, known from two well-preserved caudal vertebrae. It is the second titanosaurian taxon known from its unit, after the saltasauroid Udelartitan.

Diagnosis

  1. Anterior caudal centra strongly procoelous, with ventral margins ranging from flat to slightly transversely concave.
  2. Neural arch anteriorly displaced within the anterior caudal vertebrae.
  3. Anterior-most caudal centrum: anterior face slightly inclined (about 10 degrees); ovoid blind fossa below the anteroposterior axis, close to the condyle; wide ventral surface with paired neurovascular foramina.
  4. Anterior-most caudal centrum condyle strongly convex and slightly eccentric; prezygapophyses long, anterodorsally projected at about 30 degrees.
  5. Posterior anterior caudal centrum: anterior face strongly anteriorly inclined (about 25 degrees); centrum slightly dorsoventrally depressed.
  6. Posterior anterior caudal centrum: narrow ventral face bounded by ventrolateral ridges; condyle very strongly convex and strongly eccentric; prezygapophyses sub-horizontal (about 10 degrees).

Species

Mesetasaurus protector Soto Núñez et al., 2026

Type species

Latin for 'the one who protects'; honors José Artigas, Uruguayan national hero titled 'Protector de los Pueblos Libres'.

Holotype
FC-DPV 3740 , Colección de Vertebrados Fósiles, Departamento de Paleontología, Facultad de Ciencias, Universidad de la República
Material
Two anterior caudal vertebrae, referred to as the more anterior (3740A) and more posterior (3740B) elements.
Horizon
Guichón Formation, Coniacian–Maastrichtian, Late Cretaceous , 89.8–66.0 million years ago
Locality
Meseta de Artigas, Paysandú Department, Uruguay

References

  1. Soto Núñez, M.; Montenegro, F.; Perea, D. (2026). A new Aeolosaurini (Sauropoda, Titanosauria) from the Upper Cretaceous of Uruguay. Ameghiniana. Asociacion Paleontologica Argentina. doi:10.5710/AMGH.19.06.2026.3689 sotonúñez2026a