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Geologic formation exposed in eastern New Mexico From Wikipedia, the free encyclopedia
The Redonda Formation is a geologic formation exposed in eastern New Mexico.[1] It contains vertebrate fossils of the late Triassic Period.[2] Fossil theropod tracks have been reported from the formation.[3]
Redonda Formation | |
---|---|
Stratigraphic range: Norian ~ | |
Type | Formation |
Unit of | Chinle Group |
Sub-units | Duke Ranch, Quay, Red Peak, San Jon Creek & Wallace Ranch members |
Underlies | Entrada Formation |
Overlies | Bull Canyon Formation |
Thickness | 25–425 feet (7.6–129.5 m) |
Lithology | |
Primary | Shale |
Other | Limestone, sandstone |
Location | |
Coordinates | 34.965°N 103.701°W |
Approximate paleocoordinates | 9.9°N 43.2°W |
Region | New Mexico |
Country | ![]() |
Type section | |
Named for | Redonda Mesa |
Named by | Dobrovolny and Summerson |
Year defined | 1946 |
The formation consists of interbedded fine-grained red-brown sandstone and mudstone. It conformably overlies the Bull Canyon Formation[4] and underlies the Entrada Formation.[2]
The formation is interpreted as having been deposited in a lake with an area of about 5,000 square kilometres (1,900 sq mi).[4]
The formation has few fossil plants, with only Neocalamites reported, but it contains abundant invertebrate fossils (conchostracans and ostracods) and a diverse assemblage of vertebrate fossils.[4][3]
This section needs additional citations for verification. (September 2020) |
fish of the Redonda Formation | ||||
---|---|---|---|---|
Taxa | Presence | Notes | Images | |
Cionichthys |
Skull fragments | A redfieldiid |
![]() | |
A lungfish | ||||
Coelacanthidae indet. |
Fragmentary material | Possibly assignable to Chinlea or Quayia | ||
scales | A dapediid | |||
Abundant, found in large deathbeds | A semionotid | |||
Synornichthys |
Skull fragments | A redfieldiid | ||
Stereospondyls of the Redonda Formation | ||||
---|---|---|---|---|
Taxa | Presence | Notes | Images | |
Numerous specimens |
A metoposaurid, possibly juveniles of Koskinodon |
![]() | ||
Synapsids of the Redonda Formation | ||||
---|---|---|---|---|
Taxa | Presence | Notes | Images | |
Redondagnathus |
teeth | |||
Archosauriforms of the Redonda Formation | ||||
---|---|---|---|---|
Taxa | Presence | Notes | Images | |
Osteoderms |
An aetosaur similar to Neoaetosauroides |
![]() ![]() | ||
Numerous skulls and other skeletal remains | ||||
Osteoderms and other fragments |
A typothoracisine aetosaur related to Typothorax | |||
Snout bones and a scapulocoracoid |
A large, predatory basal crocodylomorph | |||
Osteoderms | An unusual non-archosaurian archosauriform | |||
The unit was first named as the Redonda Member of the Chinle Formation by Dobrovolny and Summerson in 1947.[1] Griggs and Read raised the unit to formation rank in 1959, and also assigned an age of late Triassic based on the presence of tracks of a bipedal dinosaur and of a phytosaur skull.[2]
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