Paleogeography Gondwana - Late Cretaceous-Early Paleogene - around 85-63 Ma

The La Colonia Formation is a geological

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...

whose strata date back to the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel et al., 2004, pp.600-604 Originally thought to be

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

(c.73-72 million years ago) in age or earlier, studies of underlying formations have made a

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interv ...

(70–66 million years ago) age more likely.Rauhut, 2003 It is divided up into three distinct facies, the first is up to thick and consists of conglomerate, the second is by far the thickest at over , consists of

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...

and

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too sm ...

, with interbeds of claystone/shale and

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

, the third is less than thick and consists of clay, and probably represents a nearshore marine

environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...

.Gasparini et al., 2015

Flora

The paleoflora was known for its aquatic components, ''Paleoazolla'' and ''Regnellidium''. However, recent paleobotanical discoveries at the Cañadón del Irupé locality have revealed the presence of a more diverse range of plants associated with these water bodies, including

pteridophytes A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as " cryptogams", meaning that their means of reproduction is hidden. ...

gymnosperms The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, γυμν� ...

, and various

angiosperms Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of br ...

. Among these are fossil leaves and fruits assignable to

Nelumbonaceae Nelumbonaceae is a family of aquatic flowering plants. ''Nelumbo'' is the sole extant genus, containing ''Nelumbo lutea'', native to North America, and ''Nelumbo nucifera'', widespread in Asia. At least four other genera, ''Nelumbites'', ''Exne ...

.Gandolfo & Cúneo, 2005

Fossil content

Turtles

Plesiosaurs

Mammals

Over 300 mammal specimens have been found in the La Colonia Formation.Rougier et al., 2009, p.225

Dinosaurs

References

Bibliography

* * * * * * * * * {{ISBN, 0-520-24209-2

* A. M. Albino. 2000. New record of snakes from the Cretaceous of Patagonia (Argentina). Geodiversitas 22(2):247-253 * N. R. Cúneo, E. J. Hermsen, and M. A. Gandolfo. 2013. ''Regnellidium'' (Salviniales, Marsileaceae) macrofossils and associated spores from the Late Cretaceous of South America. PloSOne 174(3):340-349 * J. P. O'Gorman, L. Salgado, I. A. Cerda and Z. Gasparini. 2013. First record of gastroliths associated with elasmosaur remains from La Colonia Formation (Campanian–Maastrichtian), Chubut, Patagonia Argentina, with comments on the probable depositional palaeoenvironment of the source of the gastroliths. Cretaceous Research 40:212-217 * J. O'Gorman and Z. Gasparini. 2013. Revision of Sulcusuchus erraini (Sauropterygia, Polycotylidae) from the Upper Cretaceous of Patagonia, Argentina. Alcheringa 37(2):163-176 * T. Harper, A. Parras, and G. W. Rougier. 2018. ''Reigitherium'' (Meridiolestida, Mesungulatoidea) an Enigmatic Late Cretaceous Mammal from Patagonia, Argentina: Morphology, Affinities, and Dental Evolution. Journal of Mammalian Evolution * Z. Kielan-Jaworowska, E. Ortiz-Jaureguizar, C. Vieytes, R. Pascual, and F. J. Goin. 2007. First cimolodontan multituberculate mammal from South America. Acta Palaeontologica Polonica 52(2):257-262 Geologic formations of Argentina Upper Cretaceous Series of South America Cretaceous Argentina Maastrichtian Stage of South America Sandstone formations Shale formations Siltstone formations Conglomerate formations Tidal deposits Formations Fossiliferous stratigraphic units of South America Paleontology in Argentina Geology of Chubut Province Geology of Patagonia