Neoaetosauroides
Encyclopedia
Neoaetosauroides is an extinct genus
of primitive aetosaur
. Its type
and only species
is N. engaeus. Fossil
s 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.
, 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. The upper tooth row of Neoaetosauroides runs anteriorly to the tip of the elongated snout, evidence that is incompatible with the theory of a keratin
ous beak proposed for other aetosaurs.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of primitive aetosaur
Aetosaur
Aetosaurs are an extinct order of heavily armoured, medium- to large-sized Late Triassic herbivorous archosaurs. They have small heads, upturned snouts, erect limbs, and a body covered by plate-like scutes. All aetosaurs belong to the family Stagonolepididae...
. Its type
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
and only species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
is N. engaeus. Fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s have been found from the Los Colorados Formation
Los Colorados Formation
The Los Colorados Formation is a sedimentary rock formation found in La Rioja, Argentina. It has a Norian age , and is notable for its fossils of early dinosaurs, including the coelophysoid Zupaysaurus and the "prosauropods" Coloradisaurus, Lessemsaurus, and Riojasaurus.-Dinosaurs:Indeterminate...
outcropping along the Sierra Morada River in La Rioja
La Rioja Province (Argentina)
La Rioja is a one of the provinces of Argentina and is located in the west of the country. Neighboring provinces are from the north clockwise Catamarca, Córdoba, San Luis and San Juan.-History:...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, and date back to the Norian
Norian
The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...
age of the Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
. It was the first aetosaur known from the formation, with remains being discovered in the 1960s.
Description
The genus is one of the most well-represented aetosaurs from South AmericaSouth America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, 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. The upper tooth row of Neoaetosauroides runs anteriorly to the tip of the elongated snout, evidence that is incompatible with the theory of a keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
ous beak proposed for other aetosaurs.
External links
- Neoaetosauroides in the Paleobiology DatabasePaleobiology Database' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...