Arroio Cancela fossil site
Coordinates: 29 ° 41 ′ 42.2 " S , 53 ° 47 ′ 43.5" W.
The Arroio Cancela fossil site is a fossil vertebrate site from the Upper Triassic in Brazil .
Arroio Cancela is located in the center of the city of Santa Maria, which has over 270,000 inhabitants, in the Nossa Senhora de Lourdes district of the state of Rio Grande do Sul . The site is in the 225 million year old red sediments of the Santa Maria Formation at a height of 107 meters above sea level .
Further fossil sites were discovered 35 meters above Arroio Cancela: the fossil site Largo Padre Daniel Cargnin and the fossil site Bela Vista . Cargnin had once on the eponymous fossil sites point (point 1, Figure 2) the discovery of Eucynodontier Therioherpeton cargnini made and came to the fossil reference of Bela Vista (item 2, Figure 2) fragments of a not yet determined the skull revealed. The last-mentioned sites are near the Cerrito hill and are stratigraphically higher, they already belong to the Caturrita formation .
Description of the reference
The fossil site is part of the Paleorrota Geopark and is about 600 meters from Santa Maria's central bus station. The State General Edson de Figueiredo school is around 100 meters away on the corner of Irmão Donato / Otavio Alves de Oliveira, in the immediate vicinity of a shopping center.
The area surrounded by a circle covers nine hectares and is traversed by the Cancela, an arroyo , from the street Osvaldo Aranha to the avenue Fernando Ferrari . The stream has pending red sedimentary rock exposed , thus allowing access to the fossils. The respective fossil sites are listed as points 1, 2 and 3 in Figure 2. For dimensioning: the distance from point 1 to point 3 is 185 meters, the distance from point 3 to Otavio Alves de Oliveira street is 142 meters.
Description of the fossils:
- In 1974 a specimen of a young lizard basin dinosaur of unknown systematic position was discovered. The body length is 70 centimeters from head to tail end. About 50 percent of the skull bones are present, the body skeleton (postcranium) is 70 percent preserved. The spine is complete and with connected vertebral bodies. The head of the animal was small compared to the rest of the body, the tail was long and thin, and the teeth were rounded and not pointed like those of carnivores. Presumably it is therefore a vegetarian species. (The fossil was lost).
- In 1975 a rhynchosaur was found with its skull missing. About 30 percent of the bone was preserved from the body and the vertebrae were connected (this fossil was also lost). A young rhynchosaur was recovered from the same location in 2005, but its vertebrae were separated from each other.
- In 2004, four juvenile specimens of the " mammal-like reptile " Exaeretodon were recovered. Much of the bone material of the trunk and the vertebral bodies were found separately from one another, so the bones must have undergone a major rearrangement before they were finally embedded in the sediment. In 2002, a rhynchosaur was found in the same place, which still had 60 percent of the bones from the trunk area and whose vertebrae were connected. These fossils were given to the Universidade Federal do Rio Grande do Sul (UFRGS).
Individual evidence
- ^ Oliveira, EV (2006). Reevaluation of Therioherpeton cargnini Bonaparte & Barberena, 1975 (Probainognathia, Therioherpetidae) from the Upper Triassic of Brazil. Geodiversitas 28 (3): 447-465.