La Colonia Formation | |
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Stratigraphic range: Campanian-Maastrichtian ~ | |
![]() An outcrop of the La Colonia Formation on the Somún Curá plateau that is the type locality of Chubutinectes . Photographed in 2009. | |
Type | Geological formation |
Sub-units | Lower, Middle and Upper members |
Underlies | El Buitre & Sarmiento Formations |
Overlies | Cerro Barcino & Paso del Sapo Formations |
Thickness | Up to 210–240 m (690–790 ft) Thinning to 17 m (56 ft) around Telsen |
Lithology | |
Primary | Siltstone |
Other | Sandstone, claystone, conglomerate |
Location | |
Coordinates | 43°00′S67°30′W / 43.0°S 67.5°W |
Approximate paleocoordinates | 45°42′S53°48′W / 45.7°S 53.8°W |
Region | Chubut Province |
Country | Argentina |
Extent | Cañadón Asfalto Basin |
Type section | |
Named for | Sierra La Colonia |
The La Colonia Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation. [1]
Originally thought to be Campanian (c.73-72 million years ago) in age or earlier, studies of underlying formations have made a Maastrichtian (72–66 million years ago) age more likely. [2]
It is divided up into three distinct facies, the first is up to 16 metres (52 ft) thick and consists of conglomerate, the second is by far the thickest at over 100 metres (330 ft), consists of siltstone and claystone, with interbeds of claystone/shale and sandstone, the third is less than 10 metres (33 ft) thick and consists of clay, and probably represents a nearshore marine environment. [3]
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, gymnosperms, and various angiosperms. Among these are fossil leaves and fruits assignable to Nelumbonaceae. [4]
Turtles from the La Colonia Formation | ||||||
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Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Chelidae gen. nov. [3] | sp. nov. | Norte de Cerro Bayo 2 | Skull and lower jaw; postcranial remains | Represents a new genus of chelid | ||
Patagoniaemys [3] | P. gasparinae |
| "skull fragments and several postcranial elements including a nearly complete vertebral column." [5] | A meiolaniform | ![]() | |
aff. Yaminuechelys [3] | Y. gasparinii |
| "Three specimens formed only by postcranial remains (mainly shell fragments)" | |||
Yaminuechelys [6] | Y. sulcipeculiaris |
| ||||
Fish from the La Colonia Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Metaceratodus [7] | M. potkooroki | Norte de Cerro Bayo 1 | A ceratodontid lungfish |
Plesiosaurs from the La Colonia Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Chubutinectes [8] | C. carmeloi | Several vertebrae, ribs, partial pectoral and pelvic girdles, arm and leg bones, and gastroliths | An elasmosaurid | |||
Elasmosauridae [3] | Indeterminate |
| "three postcranial specimens that preserve cervical, dorsal and caudal vertebrae, ribs and gastroliths and three vertebrae without collection number" | |||
Kawanectes [9] | K. lafquenianum | "an incomplete mandible, nine cervical vertebrae, 14 dorsal vertebrae, three sacral vertebrae and five caudal vertebrae, and almost complete left fore limb, the isolated right humerus, both femora, ilia, pubes and the right ischium" | An elasmosaurid | ![]() | ||
Sulcusuchus [3] | S. erraini | Cerro Bosta | "part of skull and mandible" | A polycotylid | ![]() | |
Ornithischians from the La Colonia Formation | ||||||
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Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Ankylosauria [3] | Indeterminate | Norte de Cerro Bayo 2 | An osteoderm | |||
Hadrosauroidea [3] | Indeterminate | Norte de Cerro Bayo 2 | Metatarsal fragment and two vertebral fragments |
Sauropods from the La Colonia Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Somphospondyli [3] | Indeterminate | Norte de Cerro Bayo 2 | "Two fragmentary caudal vertebrae" | |||
Titanomachya [10] | T. gimenezi | Norte de Cerro Bayo 2 | "Partial postcranial skeleton" | A titanosaur sauropod | ![]() |
Theropods from the La Colonia Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Carnotaurus | C. sastrei | Pocho Sastre | "Nearly complete skeleton and skull" [11] | An abelisaurid [12] [13] | ![]() | |
Enantiornithine [14] | Indeterminate | A distal humerus | ||||
Koleken [3] [15] | K. inakayali | Norte de Cerro Bayo 1 | "Quite complete and partially articulated skeleton" | An abelisaurid. | ![]() | |
Neornithes [16] | Indeterminate | A distal ulna | ||||
Theropoda [3] | Indeterminate | Norte de Cerro Bayo 2 | "Metatarsal fragments of a single individual" | |||
Over 300 mammal specimens have been found in the La Colonia Formation. [17]
Mammals of the La Colonia Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Argentodites | A. coloniensis [18] | A possible gondwanatherian or multituberculate | ||||
Coloniatherium | C. cilinskii [19] | A meridiolestidan | ||||
Ferugliotherium | F. windhauseni [18] | A possible gondwanatherian or multituberculate | ||||
Reigitherium | R. bunodontum [20] | A meridiolestidan |
Fossils of madtsoiids, and perhaps boids, have been found in the formation. [21]
Snakes from the La Colonia Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Alamitophis | A. argentinus [21] | Trunk vertebra | A madtsoiid snake | |||
Eomadtsoia | E. ragei [22] | A madtsoiid Snake | ||||
Carnotaurus is a genus of theropod dinosaur that lived in South America during the Late Cretaceous period, probably sometime between 72 and 69 million years ago. The only species is Carnotaurus sastrei. Known from a single well-preserved skeleton, it is one of the best-understood theropods from the Southern Hemisphere. The skeleton, found in 1984, was uncovered in the Chubut Province of Argentina from rocks of the La Colonia Formation. Carnotaurus is a derived member of the Abelisauridae, a group of large theropods that occupied the large predatorial niche in the southern landmasses of Gondwana during the late Cretaceous. Within the Abelisauridae, the genus is often considered a member of the Brachyrostra, a clade of short-snouted forms restricted to South America.
Rocasaurus is a genus of titanosaurian sauropod that lived in South America. Rocasaurus was discovered in Argentina in 2000, within the Allen Formation which is dated to be middle Campanian to early Maastrichtian in age. This genus grew up to 8 metres (26 ft) long, making it one of the smaller sauropods. It seems to be closely related to saltasaurid dinosaurs, like Saltasaurus and Neuquensaurus.
Tuarangisaurus is an extinct genus of elasmosaurid known from New Zealand. The type and only known species is Tuarangisaurus keyesi, named by Wiffen and Moisley in 1986.
Aristonectes is an extinct genus of large elasmosaurid plesiosaurs that lived during the Maastrichtian stage of the Late Cretaceous. Two species are known, A. parvidens and A. quiriquinensis, whose fossil remains were discovered in what are now Patagonia and Antarctica. Throughout the 20th century, Aristonectes was a difficult animal for scientists to analyze due to poor fossil preparation, its relationships to other genera were uncertain. After subsequent revisions and discoveries carried out from the beginning of the 21st century, Aristonectes is now recognised as the type genus of the subfamily Aristonectinae, a lineage of elasmosaurids characterized by an enlarged skull and a reduced length of the neck.
The Cerro Barcino Formation is a geological formation in South America whose strata span the Early Cretaceous to the earliest Late Cretaceous. The top age for the formation has been estimated to be Cenomanian. Earlier estimates placed the formation until the Campanian.
The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous (middle Campanian to early Maastrichtian. Dinosaur remains are among the fossils that have been recovered from the formation. Indeterminate chelid remains and other vertebrates have also been discovered in this formation.
The Chorrillo Formation, also named as Chorillo Formation, is a Maastrichtian geologic formation in southern Patagonia, Argentina. The formation is more than 50 metres (160 ft) thick and underlies the Calafate Formation and rests on top of the La Irene Formation.
Austrocheirus is an extinct genus of theropod dinosaur that lived during the Late Cretaceous period. It was named and described by Martin Ezcurra, Federico Agnolin and Fernando Novas in 2010. It contains the type species Austrocheirus isasii. The generic name means "southern hand". The specific epithet honours discoverer and preparator Marcelo Pablo Isasi.
Patagoniaemys is an extinct genus of stem turtle which existed in central Patagonia, Chubut Province, Argentina during the late Cretaceous epoch. It is known from skull fragments and several postcranial elements including a nearly complete vertebral column recovered from the La Colonia Formation. It was first named by Juliana Sterli and Marcelo S. de la Fuente in 2011, and the type species is Patagoniaemys gasparinae.
The Snow Hill Island Formation is an Early Maastrichtian geologic formation found on James Ross Island, James Ross Island group, Antarctica. Remains of a paravian theropod Imperobator antarcticus have been recovered from it, as well as the elasmarian ornithopods Trinisaura santamartaensis, Biscoveosaurus and Morrosaurus antarcticus, the ankylosaurian Antarctopelta oliveroi, and the shark Notidanodon sp. Alongside these described genera are also the remains of indeterminate elasmosaurids, lithostrotian titanosaurs and an indeterminate pterosaur.
Yaminuechelys is an extinct genus of chelid turtle from Argentina and the Dorotea Formation of Chile. The genus first appeared during the Late Cretaceous and became extinct during the Late Paleocene.
Kawanectes is a genus of elasmosaurid plesiosaur, a type of long-necked marine reptile, that lived in the marginal marine environment of Late Cretaceous Patagonia. It contains one species, K. lafquenianum, described in 2016 by O'Gorman.
The Cañadón Asfalto Basin is an irregularly shaped sedimentary basin located in north-central Patagonia, Argentina. The basin stretches from and partly covers the North Patagonian Massif in the north, a high forming the boundary of the basin with the Neuquén Basin in the northwest, to the Cotricó High in the south, separating the basin from the Golfo San Jorge Basin. It is located in the southern part of Río Negro Province and northern part of Chubut Province. The eastern boundary of the basin is the North Patagonian Massif separating it from the offshore Valdés Basin and it is bound in the west by the Patagonian Andes, separating it from the small Ñirihuau Basin.
Kaikaifilusaurus is an extinct genus of rhynchocephalians in the family Sphenodontidae from the Late Cretaceous of South America. Fossils of the genus were found in Cenomanian sediments of the Candeleros Formation and Turonian layers of the Huincul Formation, both of the Neuquén Basin and the Albian strata of the Cerro Barcino Formation in the Cañadón Asfalto Basin, all in Patagonia, Argentina. The genus contains two species, K. minimus and the type species K. calvoi.
Meiolaniformes is an extinct clade of stem-group turtles, defined as all taxa more closely related to Meiolania than to Cryptodira and Pleurodira. It is known from the Early Cretaceous to the Holocene of Australia, Oceania and South America. Some Eurasian taxa have been suggested to be part of the group, but this is disputed.
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Yatenavis is an extinct genus of enantiornithine bird from the Late Cretaceous Chorrillo Formation of Santa Cruz Province, Argentina. The genus contains a single species, Y. ieujensis, known from a partial humerus.
Chubutinectes is an extinct genus of elasmosaurid plesiosaur from the Late Cretaceous La Colonia Formation of Argentina. The genus contains a single species, C. carmeloi, known from a partial skeleton and associated gastroliths.
Titanomachya is an extinct genus of titanosaurian sauropod dinosaur from the Late Cretaceous La Colonia Formation of Argentina. The genus contains a single species, T. gimenezi. It is a relatively small titanosaur, weighing around 7.8 tonnes.
Koleken is a genus of carnotaurin abelisaurid from the Maastrichtian La Colonia Formation in the Chubut Province of Argentina. The type and only species is K. inakayali, known from one immature specimen about six years old in minimum age.