Redonda Formation
Geologic formation exposed in eastern New Mexico
The Redonda Formation is a geologic formation exposed in eastern New Mexico. It contains vertebrate fossils of the late Triassic Period. Fossil theropod tracks have been reported from the formation.
01Description
The formation consists of interbedded fine-grained red-brown sandstone and mudstone. It conformably overlies the Bull Canyon Formation and underlies the Entrada Formation.
The formation is interpreted as having been deposited in a lake with an area of about 5,000 square kilometres (1,900 sq mi).
02Fossils
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.
Vertebrate fauna
Fish
| fish of the Redonda Formation | ||||
|---|---|---|---|---|
| Taxa | Presence | Notes | Images | |
| 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 | |||
| Skull fragments | A redfieldiid | |||
Stereospondyls
| Stereospondyls of the Redonda Formation | ||||
|---|---|---|---|---|
| Taxa | Presence | Notes | Images | |
| Numerous specimens |
A metoposaurid, possibly juveniles of Koskinonodon |
|||
Synapsids
| Synapsids of the Redonda Formation | ||||
|---|---|---|---|---|
| Taxa | Presence | Notes | Images | |
| teeth | ||||
Archosauriforms
| 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 | |||
03History of investigation
The unit was first named as the Redonda Member of the Chinle Formation by Dobrovolny and Summerson in 1947. 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.
Sources and credits
This article is adapted from the Wikipedia article “Redonda Formation”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Semionotus model.jpg by Ghedoghedo, CC BY-SA 4.0
- Apachesaurus1DB.jpg by Dmitry Bogdanov, CC BY-SA 3.0
- Redondasaurus bermani at CMNH 04.jpg by User:Piotrus, CC BY-SA 3.0
- Vancleavea.jpg by Smokeybjb, CC BY-SA 3.0
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