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Temporal range: Late Triassic
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Aetosauria
Family: Stagonolepididae
Genus: Neoaetosauroides
Bonaparte, 1969
  • N. engaeus Bonaparte, 1969 (type)

Neoaetosauroides is an extinct genus of primitive aetosaur. Its type and only species is N. engaeus. Fossils have been found from the Los Colorados Formation outcropping along the Sierra Morada River in La Rioja, Argentina, and date back to the Norian age of the Late Triassic. It was the first aetosaur known from the formation, with remains being discovered in the 1960s.[1][2][3]


Diagram showing Neoaetosauroides osteoderms with labeled terminology

The genus is one of the most well represented aetosaurs from South America, with some specimens being fully articulated. Two rows of dorsal osteoderms run paramedially along either side of the spine. Ventral osteoderms were also present. Unlike most other aetosaurs, the fourth finger was longer than the second and third. Additionally, the number of phalanges in the fifth digit was lower than other aetosaurs.[4] The upper tooth row of Neoaetosauroides runs anteriorly to the tip of the elongated snout, evidence that is incompatible with the theory of a keratinous beak proposed for other aetosaurs.[5]


  1. ^ Bonaparte, J. F. (1969). Los tetrápodos triásicos de Argentina. 1º International Symposium of Gondwana (Mar del Plata, 1967):307-325.
  2. ^ Bonaparte, J. F. (1971). Los tetrápodos del sector superior de la Formación Los Colorados, La Rioja, Argentina (Triásico Superior). Opera Lilloana 22:87-102.
  3. ^ Bonaparte, J. F. (1978). El Mesozoico de América del Sur y sus tetrápodos. Opera Lilloana, 26, 596 pp.
  4. ^ Desojo, J. B. and Báez, A. M. (2005). El esqueleto postcraneano de Neoaetosauroides (Archosauria: Aetosauria) del Triásico Superior del centro-oeste de Argentina. Ameghiniana 42(1):115-126.
  5. ^ Desojo, J. B. and Báez, A. M. (2007). Cranial morphology of the Late Triassic South American archosaur Neoaetosauroides engaeus: evidence for aetosaurian diversity. Palaeontology 50(1):267-276.

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