The Coihaique Group is a

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

s in northwestern

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

. From top to bottom the formations that make the group are Apeleg, Katterfeld and

Toqui Toqui (or Toki) (Mapudungun for ''axe'' or ''axe-bearer'') is a title conferred by the Mapuche (an indigenous Chilean and Argentines, Argentinian people) on those chosen as leaders during times of war. The toqui is chosen in an assembly or parl ...

. The contact between the formations of the group are diachronous with Katterfeld Formation interfingering with the formations on top and below it. The lower and upper boundaries of the group are

unconformities An unconformity is a buried erosion surface, erosional or non-depositional surface separating two Rock (geology), rock masses or Stratum, strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer ...

formed by

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

. The older parts of Coihaique Group represent a

marine transgression A marine transgression is a geologic event where sea level rises relative to the land and the shoreline moves toward higher ground, resulting in flooding. Transgressions can be caused by the land sinking or by the ocean basins filling with water ...

while the younger parts evidences a

return Return may refer to: In business, economics, and finance * Return on investment (ROI), the financial gain after an expense. * Rate of return, the financial term for the profit or loss derived from an investment * Tax return, a blank document or t ...

to non-marine conditions.

Fossils in Toqui Formation

The rock formation preserves

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s from the

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

period of the

Mesozoic Era The Mesozoic Era is the era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of archosaurian reptiles such as the dinosaurs, and of gymnosperms s ...

. Fossils of ''

Chilesaurus ''Chilesaurus'' is an extinct genus of herbivorous dinosaur. While its exact classification is uncertain, many researchers believe it is a theropod, with a minority of academics suggesting that it may be an ornithischian. The type and only know ...

'' (147 Ma) were found in the

Aysén Region The Aysén del General Carlos Ibáñez del Campo Region (, , '), often shortened to Aysén Region or Aisén,Examples of name usage1, official regional government site refers to the region as "Región de Aysén"., Chile's official meteorological ...

of Patagonia. It is an extinct genus of

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

s in the family

Tetanurae Tetanurae (/ˌtɛtəˈnjuːriː/ or "stiff tails") is a clade that includes most Theropoda, theropod dinosaurs, including Megalosauroidea, megalosauroids, Allosauroidea, allosauroids, and Coelurosauria, coelurosaurs (which includes Tyrannosauroi ...

.news.nationalgeographic.com National Geographic.com: "T. rex's Oddball Vegetarian Cousin Discovered"
by Michael D. Lemonick, 2015-04-27. The fossil record also comprises a sauropod

Titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

, a Camarasaur and a

Diplodocid Diplodocids, or members of the family Diplodocidae ("double beams"), are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the Earth, including '' Diplodocus'' and '' Supersaurus'', some of which may ha ...

References

Geologic groups of Chile Jurassic System of South America Late Jurassic South America Jurassic Chile Lower Cretaceous Series of South America Cretaceous Chile Shale groups Sandstone groups

Groups A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

Paleontology in Chile Geology of Aysén Region {{SouthAm-geologic-formation-stub

Fossils in Toqui Formation

See also

References