Open Paleo

Leyesaurus

Apaldetti et al., 2011 lih-shih-SOR-us

Named for the Leyes family of Balde de Leyes, who discovered the holotype, combined with Greek 'sauros' meaning 'lizard'. The species name refers to the Marayes-El Carrizal Basin where the holotype was found.

Leyesaurus is an extinct genus of massospondylid sauropodomorph dinosaur known from the San Juan Province, northwestern Argentina.

Diagnosis

  1. Sharply acute angle (50°) formed by ascending process of maxilla with alveolar margin
  2. Straight ascending process of maxilla with longitudinal ridge on lateral surface
  3. Noticeably bulging labial side of maxillary teeth
  4. Greatly elongated cervical vertebrae with length/height ratio >5
  5. Neural spines of cervical vertebrae with sinuous dorsal margin and short epipophyses
  6. Shelf-like and medially deflected proximal articular surface of metatarsal III
  7. Hook-shaped medial process on metatarsal III with deep ventral foramen

Species

Leyesaurus marayensis Apaldetti et al., 2011

Type species

Named for the Marayes-El Carrizal Basin in San Juan Province, Argentina, where the holotype was discovered.

Holotype
PVSJ 706 , División de Paleontología de Vertebrados del Museo de Ciencias Naturales y Universidad Nacional de San Juan
Material
Partial skeleton including skull with articulated mandible, cervical vertebrae (C3-C7), anterior and middle caudal vertebrae, left scapula/coracoid/humerus, right pubis, both ischia, left pes with distal tarsals and metatarsals.
Horizon
Balde de Leyes Formation, Early Jurassic
Locality
Balde de Leyes, San Juan, Argentina

References

  1. Apaldetti, C.; Martínez, R. N.; Alcober, O. A.; Pol, D. (2011). A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina. PLoS ONE 6(11): e26964. Public Library of Science (PLoS). doi:10.1371/journal.pone.0026964 apaldetti2011a
  2. Colombi, C. E.; Santi Malnis, P.; Correa, G. A.; Martínez, R. N.; Fernández, E.; Abelín, D.; Praderio, A.; Apaldetti, C. G.; Alcober, O.; Drovandi, J. (2015). La Formación Balde de Leyes (nov. Nom.), una nueva unidad estratigráfica de la cuenca triásica de Marayes-El Carrizal [The Balde de Leyes Formation, a new stratigraphic unit from the Triassic Marayes-El Carrizal Basin, San Juan]. Revista de la Asociación Geológica Argentina 72(4): 445-455. Asociación Geológica Argentina.

    Erects the Balde de Leyes Formation for the top of the succession and gives its vertebrate fauna as this species alone.

    colombi2015a
  3. Martínez, R. N.; Apaldetti, C.; Correa, G.; Colombi, C. E.; Fernández, E.; Santi Malnis, P.; Praderio, A.; Abelín, D.; Benegas, L. G.; Aguilar-Cameo, A.; Alcober, O. A. (2015). A new Late Triassic vertebrate assemblage from northwestern Argentina. Ameghiniana 52: 379-390. doi:10.5710/AMGH.27.04.2015.2889

    Puts every Leyesaurus specimen in a unit overlying the Quebrada del Barro Formation, and suggests an Early Jurassic age for it.

    martínez2015a
  4. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  5. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026b