Dorotea Formation
Geological formation in the Río de Las Chinas Valley, Magallanes Basin, Chile
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The Dorotea Formation is a geological formation in the Río de Las Chinas Valley of the Magallanes Basin in Patagonian Chile whose strata date back to the Campanian to Maastrichtian of the Late Cretaceous.[1]
| Dorotea Formation | |
|---|---|
| Stratigraphic range: Late Campanian-Maastrichtian ~ | |
| |
| Type | Geological formation |
| Underlies | Man Aike Formation |
| Overlies | Tres Pasos Formation |
| Thickness | 100–350 m (330–1,150 ft) |
| Lithology | |
| Primary | Sandstone, claystone |
| Other | Conglomerate |
| Location | |
| Coordinates | 50.7°S 72.5°W |
| Approximate paleocoordinates | 52.9°S 60.5°W |
| Region | Magallanes Region |
| Country | Chile |
| Extent | Río de Las Chinas Valley, Magallanes Basin |
| Type section | |
| Named for | Sierra Dorotea |
| Named by | Katz |
| Year defined | 1963 |
  Dorotea Formation (Chile) | |
Description
The Dorotea Formation was first described by Katz in 1963. The formation comprises sandstones with frequent conglomerate lenses, concretionary levels and claystones. The Dorotea Formation includes calcareous sandstones with abundant marine invertebrate and fragmentary vertebrate fossils. Hervé et al. (2004) obtained a maximum radiometric age of 67.4 ± 1.5 Ma from detrital zircons contained in sandstones of the Dorotea Formation.[2] Near the top of the formation is an iridium anomaly, correlated with the Cretaceous–Paleogene boundary; this is the southernmost K–Pg boundary site known from South America.[3]
The mudstones and sandstones of the formation were deposited in a fluvial environment. The formation conformably overlies the Tres Pasos Formation and is unconformably overlain by the Lutetian to Bartonian Man Aike Formation.[4] The thickness of the formation ranges from 100 metres (330 ft) in the Sierra Baguales in the north to 350 metres (1,150 ft) in the eponymous Sierra Dorotea in the south.[5]
Fossil content
The following fossils were reported from the formation:[6]
Amphibians
Reptiles
| Reptiles of Dorotea Formation | |||||
|---|---|---|---|---|---|
| Taxa | Species | Locality | Material | Notes | Images |
| Aristonectinae[8] | Indeterminate | ||||
| Aristonectes | A. sp.[8] | ||||
| Yaminuechelys | cf. Yaminuechelys sp.[7] | ||||
| Panchelidae[7] | Indeterminate | Saurópodo sector (Section SP-17). | Distal fragment of right humerus and distal end of right femur. | ||
| Elasmosauridae | Indeterminate | ||||
Dinosaurs
Ornithischians
| Ornithischians of Dorotea Formation | |||||
|---|---|---|---|---|---|
| Taxa | Species | Locality | Material | Notes | Images |
| Gonkoken[9] | G. nanoi | Loma Koken | Several incomplete specimens belonging to individuals of different ages | A hadrosauroid |  |
| Ornithischia[7] | Indeterminate | ||||
| Stegouros | S. elengassen | CPAP-3165 (holotype), a holotype consists of a relatively complete skeleton with a skull and lower jaws. | A parankylosaur |  | |
Saurischians
| Saurischians of Dorotea Formation | ||||
|---|---|---|---|---|
| Taxa | Species | Material | Notes | Images |
| Enantiornithes[10] | Indeterminate | |||
| Megaraptoridae[10] | Indeterminate | |||
| Ornithurae[10] | Indeterminate | |||
| Sauropoda[7] | Indeterminate | |||
| Unenlagiinae[10] | Indeterminate | |||
| Theropoda[7][10] | Indeterminate | |||
Mammals
| Mammals of Dorotea Formation | |||||
|---|---|---|---|---|---|
| Taxa | Species | Locality | Material | Notes | Images |
| Magallanodon[11] | M. baikashkenke[11] | Mammal quarry from the Río de Las Chinas valley | A first lower left molariform | A gondwanathere | |
| Orretherium | O. tzen[12] | Mammal quarry from the Río de Las Chinas valley | A fragmented lower jaw. | A mesungulatid mammal | |
| Mammalia[7] | Indeterminate | ||||
| Yeutherium | Y. pressor[13] | 'Black Bone' Locality | A left maxilla fragment with M1, roots of M2 and mesial roots of M3. | A subantarctic reigitheriidae mammal | |
Fish
| Fish of Dorotea Formation | ||||
|---|---|---|---|---|
| Taxa | Species | Material | Notes | Images |
| Ischyrhiza | I. chilensis[5] | |||
| Carcharias | C. sp.[5] | |||
| Serratolamna | Indeterminate[5] | |||
Invertebrates
| Invertebrates of Dorotea Formation | |||||
|---|---|---|---|---|---|
| Taxa | Species | Locality | Material | Notes | Images |
| Dorotheus | Dorotheus guidensis[14] | ||||
| Pterotrigonia | P. cazadoriana[2] | ||||
| Gunnarites | G. sp.[2] | ||||
| Pachydiscus | P. aff. gollevilensis[2] | ||||
See also
- List of dinosaur-bearing rock formations
- Quiriquina Formation
- Chorrillo Formation
- Allen Formation, Campanian to Maastrichtian fossiliferous formation of the Neuquén Basin
- Angostura Colorada Formation, Campanian to Maastrichtian fossiliferous formation of the North Patagonian Massif
- La Colonia Formation, Campanian to Maastrichtian formation of the Cañadón Asfalto Basin
- Colorado Formation, Campanian to Maastrichtian fossiliferous formation of the Colorado Basin
- Lago Colhué Huapí Formation, Campanian to Maastrichtian fossiliferous formation of the Golfo San Jorge Basin
- Lopez de Bertodano Formation
- Snow Hill Island Formation
- Sobral Formation