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Trincheras Formation

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The Trincheras Formation ( Spanish : Formación Trincheras , Kitr) is a geological formation of the Altiplano Cundiboyacense , Eastern Ranges of the Colombian Andes . The formation consisting of a lower unit of calcareous shales and an upper sequence of shales dates to the Early Cretaceous period; Early Aptian epoch and has a maximum thickness of 1,260 metres (4,130 ft). The formation, deposited in a marine platform environment, part of a transgressive cycle, hosts ammonite , bryozoan , mollusc and echinoid fossils.

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18-487: The formation was defined and named in 1969 by Cáceres and Etayo after Quebrada Trincheras, Apulo , Cundinamarca . The Trincheras Formation has a maximum thickness of 1,260 metres (4,130 ft), and is characterised by a sequence of claystones with intercalated limestones and sandstones . Fossils of the ammonites Heinzia sp. , Pseudohaploceras sp. , Heminautilus etheringtoni , Cheloniceras sp. and bryozoans , molluscs and echinoids have been found in

36-522: A limestone nodule during the 1990s in Ricaurte, northeast of Villa de Leyva . The exact site of the find is unknown, however the rock matrix in which the fossil was located contains ammonite fossils bellowing to the species Gerhardtia galeatoides and Lytoceras sp., that allow the establishment of their origin in the middle Paja Formation which has been placed in the late Barremian, around 130 million years old. The fossil consists of vertebrae from

54-557: A polytomy among basal forms including Padillasaurus , Abydosaurus , Brachiosaurus and Giraffatitan , while Cedarosaurus and Venenosaurus were occasionally recovered as sister taxa . Unlike Cretaceous brachiosaurids from North America, in which the spinous process of the caudal vertebrae leaned slightly forward, those of Padillasaurus were angled rearward. Cladogram from Carballido et al ., 2015: Padillasaurus Brachiosaurus Abydosaurus Giraffatitan Venenosaurus Cedarosaurus In 2017,

72-441: A height equal to half of its width. Padillasaurus was initially classified in the family Brachiosauridae based on its morphology. It had cavities in the sacral vertebrae that had no connection with the hollow interior of the vertebra, therefore lacking a true pleurocoel . This feature links it to the brachiosaurids. A cladistic analysis was unable to determine the exact relationships of Padillasaurus with other genera, finding

90-472: A single partial axial skeleton . Initially described as a brachiosaurid, it was considered to be the first South American brachiosaurid ever discovered and named. Before its discovery, the only known brachiosaurid material on the continent was very fragmentary and from the Jurassic period. However, a more recent study finds it to be a basal somphospondylan . The fossil was discovered by local farmers in

108-676: Is a Colombian paleontologist and geologist . His contributions on the paleontology in Colombia has been mainly on the descriptions of ammonites and Etayo has helped describing many fossiliferous geologic formations of Colombia . Etayo obtained his MSc. degree in geology and geophysics from the Universidad Nacional de Colombia in 1963, and his PhD in paleontology from the University of California, Berkeley in 1975. In 1962, Etayo Serna published his first work about

126-584: Is named after Villa de Leyva, which is located nearby to where the vertebrae of the holotype specimen were discovered. Padillasaurus is the first record of a Cretaceous brachiosaurid of South America; previous findings of that time were only known in North America. Although fragmentary remains of possible brachiosaurids are known from the Jurassic of Patagonia in Argentina, Padillasaurus it

144-482: Is the first member officially named from South America. It is also the latest brachiosaurid known from the ancient continent of Gondwana . Padillasaurus was a medium-sized titanosauriform. Because of the few remains found is difficult to determine what would have been its body size, but may have had between 16 and 18 meters long and weigh about 10 tonnes. Padillasaurus is distinguished from other titanosauriforms in having its caudal vertebrae weakly expanded to

162-593: The Late Paleocene to Early Eocene Bogotá Formation south of Bogotá , has been named in honour of Etayo. This list is a selection. Padillasaurus Padillasaurus is an extinct genus of titanosauriform sauropod known from the Early Cretaceous ( Barremian stage) Paja Formation in Colombia . It contains a single species , Padillasaurus leivaensis , known only from

180-797: The Murca- Guayabal - Nimaima Anticlinal and along the roads between Pacho and La Palma and Útica -La Peña. The formation also crops out around San Joaquín east of La Mesa , and on the right bank of the Bogotá River near Apulo. The reverse Bituima Fault thrusts the Trincheras Formation on top of the Güagüaquí Group , while the Bogotá River Fault laterally displaces the formation near Anapoima . Fernando Etayo Fernando Etayo Serna

198-634: The Trincheras Formation. The Trincheras Formation is the lowermost unit of the Villeta Group , and conformably overlies the Murca , La Naveta and Útica Formations . The formation is overlain in a transitional pattern by the Socotá and El Peñón Formations . The Trincheras Formation is subdivided into the El Tigre and Anapoima Members. The age has been estimated to be Early Aptian . Stratigraphically,

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216-423: The diapophysis and the body of the vertebra. The anterior caudal vertebrae are flattened or slightly concave from the front and from behind, or vice versa. The neural arches are positioned relatively forward. These have long ridges that run between the protuberances of the joint face and body of the vertebra. The side projections are oriented obliquely backwards and have a convex lower area. The caudal vertebrae have

234-603: The formation is time equivalent with the fossiliferous Paja Formation of Boyacá and the Las Juntas Formation . The formation has been deposited in a marine well oxygenated platform environment . In terms of sequence stratigraphy , this phase was transgressional . The Trincheras Formation is apart from its type locality in Apulo , found near La Mesa and Anapoima , in the Villeta Anticlinal,

252-415: The sides, and displaying divided side projections. The species shows some typical basic features of Titanosauriformes: the vertebra is opisthocoelic, with a convex front section and the back concave. The edges show large pleurocoels, pneumatic processes that connected to the hollow interior of the body of the vertebra, which consisted of several hollow cavities. The spine also had an additional lamina between

270-472: The species Codakia orbicularis and Codakia orbiculata . He has defined many geologic formations of Colombia in the 1960s and 1970s. Etayo, together with fellow paleontologist María Páramo , collaborated in describing the first dinosaur fossil found in Colombia, Padillasaurus from the Paja Formation , close to Villa de Leyva , Boyacá . His work has been focused on the descriptions of

288-400: The torso, sacrum and tail: all presumed to be from one individual. This specimen is the holotype assigned to the catalogue number JACVM 0001 ; this includes a rear dorsal vertebra, a series from the last two sacral vertebrae and first eight caudal vertebrae (these caudal vertebrae were found without their chevrons ). The sacral vertebrae have been identified as the fourth and fifth. This fossil

306-667: The various ammonites found in the same formation. He also co-authored the 2016 publication about Stenorhynchosaurus munozi , found in the same formation. Etayo has published in Spanish and English. In 1975, the year Etayo received his PhD degree, he was awarded the Louderbach Memorial Award in Stratigraphy from the University of California, Berkeley. The ungulate Etayoa bacatensis , found in

324-661: Was donated by the farmers and became part of the collection at the museum of the Junta de Acción Comunal de la Vereda de Monquirá. Padillasaurus was originally described and named by José L. Carballido, Diego Pol, Mary L. Parra Ruge, Santiago Padilla Bernal, María E. Páramo-Fonseca y Fernando Etayo-Serna in 2015. The name of the genus pays homage to Carlos Bernardo Padilla, the founder of the Centro de Investigaciones Paleontológicas in Villa de Leyva , Colombia. The specific name, leivaensis ,

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