The Urbión Group is a geological group in

Castile and León Castile and León ( es, Castilla y León ; ast-leo, Castiella y Llión ; gl, Castela e León ) is an autonomous community in northwestern Spain. It was created in 1983, eight years after the end of the Francoist regime, by the merging of the ...

and La Rioja, Spain whose strata date back to the

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

( late Hauterivian to late Barremian. The formations of the group comprise a sequence of brown

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

s in a matrix of black

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

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) ...

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 ...

s and conglomerates deposited under terrestrial conditions, in alluvial fan and

fluvial In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...

environments 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 ...

. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel et al., 2004, pp.556-563

Description

The Urbión Group, named after the Picos de Urbión, comprises a sequence of brown

s in a matrix of black

s and conglomerates deposited under terrestrial conditions, in alluvial fan and

. The contact with the overlying

Enciso Group The Enciso Group is a geological formation in La Rioja, Spain whose strata date back to the Early Cretaceous.Presa de Enciso tracksite (2PRE)
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org

Fossil content

''Demandasaurus darwini''

The fossil bones of ''

Demandasaurus ''Demandasaurus'' (meaning " Demanda lizard") is a genus of rebbachisaurid sauropod dinosaur from early Cretaceous (late Barremian – early Aptian stage) deposits of Spain. ''Demandasaurus'' is known from an incomplete but associated skeleton t ...

'' were recovered in the "Tenadas de los Vallejos II" quarry, located southwest of the town of Salas de los Infantes (Province of Burgos, northern Spain). In geological terms, this area lies within the western Cameros Basin, which is located in the north−westernmost part of the

Iberian Range Iberian refers to Iberia. Most commonly Iberian refers to: *Someone or something originating in the Iberian Peninsula, namely from Spain, Portugal, Gibraltar and Andorra. The term ''Iberian'' is also used to refer to anything pertaining to the fo ...

, outcropping in the provinces of Burgos, Soria and La Rioja. This basin is one of the most subsident basins formed during the rift interval at the end of the Jurassic and the Early Cretaceous, which affected this part of the Iberian Peninsula. The sediments of the Tenadas de los Vallejos II quarry belong to the

Castrillo de la Reina Formation The Castrillo de la Reina Formation is a geological formation in Spain. It is late Barremian to early Aptian in age. It interpreted as a fluvial deposit. It primarily consists of red clay, with ribbon shaped sandstone channel fills. The rebbachisau ...

and comprise red clay beds intercalated with sheet−like sandstone channel fills that are interpreted as

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

and

fluvial channel In physical geography, a channel is a type of landform consisting of the outline of a path of relatively shallow and narrow body of water or of other fluids (e.g., lava), most commonly the confine of a river, river delta or strait. The word is ...

deposits respectively. The fluvial system of the Castrillo de la Reina Formation shows a braided channel pattern with well developed and drained floodplains. This lithostratigraphic unit belongs to the fifth depositional sequence of the six ones that divide the basin. The age of the fifth depositional sequence is Late Barremian to Early Aptian as is suggested by charophyte and

ostracod Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...

biostratigraphy Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock Stratum, strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictiona ...

. The Tenadas de los Vallejos II site was discovered in 1999 during prospection work carried out by the Archaeological−Palaeontological Group of Salas de los Infantes (Colectivo Arqueológico−Paleontológico de Salas de los Infantes, CAS). Ten caudal vertebrae, a haemal arch, two ischia and a femur, as well as bone fragments were collected in the site. Excavations were carried out during the years 2002–2004, covering a surface area of some . Approximately 810 skeletal elements and bone fragments were recovered, and most of them belong to a single specimen of rebbachisaurid sauropod. The remains were found disarticulated in the same bed and in close proximity to each other. The neural arches of the vertebrae are firmly co−ossified to the centra. There are no anatomically repeated elements, and the bones correspond presumably to a single individual. The relative size of the bones suggests a medium−sized individual whose total length was approximately . In addition, several vertebral centra and femur fragments from a small

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world ...

, two

spinosaur The Spinosauridae (or spinosaurids) are a clade or family of tetanuran theropod dinosaurs comprising ten to seventeen known genera. They came into prominence during the Cretaceous period. Spinosaurid fossils have been recovered worldwide, includi ...

id theropod vertebrae and a crocodile tooth were recovered from the site.Torcida et al., 2011, p.537

Other fossils

Among others, the following fossils have been reported from the Urbión Group:Urbión Group
at

.org * '' Chitracephalus dumonii'' - Pinilla de los Moros Formation * '' Larachelus morla'' - Pinilla de los Moros Formation * '' Europatitan eastwoodi'' -

* '' Goniopholis sp.'' * '' Lepidotes sp.'' * '' Polacanthus sp.'' * Baryonychinae indet. * Crocodyliformes indet. * Hypsilophodontidae indet. * Iguanodontia indet. * Rhabdodontidae indet. * Testudines indet. * ichnofossils ** '' Brachyguanodonipus sp.''

Correlation

References

Bibliography

* *

Material was copied from this source, which is available under
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* {{ISBN, 0-520-24209-2

* A. Pérez-García and X. Murelaga. 2012. Larachelus morla, gen. et sp. nov., a new member of the little-known European Early Cretaceous record of stem cryptodiran turtles. Journal of Vertebrate Paleontology 32(6):1293-1302 * P. Ansorena, I. Díaz Martínez, and F. Pérez Lorente. 2008. Mina Victoria (Navajún) y Valdeperillo (Cornago). Nuevos yacimientos de icnitas de dinosaurio en El Grupo de Urbión (Cuenca de Cameros. La Rioja. España) ina Victoria (Navajún) and Valdeperillo (Cornago). New dinosaur footprint localities in the Urbión Group (Cameros Basin. La Rioja. Spain) Zubía 25–26:75-96 * F. Torcida Fernández Baldor. 2005. Los dinosaurios de Castilla y León he dinosaurs of Castilla y León Patrimonio Histórico de Castilla y León 6(23):23-34 * J. I. Ruiz Omeñaca and J. I. Canudo. 2003. Dinosaurios (Saurischia, Ornithischia) en el Barremiense (Cretácico Inferior) de la península Ibérica inosaurs (Saurischia, Ornithischia) in the Barremian (Lower Cretaceous) of the Iberian peninsula In F. Pérez Lorente (ed.), Dinosaurios y Otros Reptiles Mesozóicos de España 269-312 * F. Torcida Fernández, L. A. Izquierdo Montero, P. Huerta Hurtado, D. Montero Huerta, and G. Pérez Martínez. 2003. Dientes de dinosaurios (Theropoda, Sauropoda), en el Cretácico Inferior de Burgos (España) eeth of dinosaurs (Theropoda, Sauropoda), in the Lower Cretaceous of Burgos (Spain) In F. Pérez Lorente, M. M. Romero Molina & P. Rivas Carrera (eds.), Dinosaurios y Otros Reptiles Mesozoicos en España. Congreso Internacional sobre Dinosaurios y otros Reptiles Mesozoicos en España, Logroño 335-346 * F. Pérez Lorente. 2002. La distribución de yacimientos y de tipos de huellas de dinosaurios en la Cuenca de Cameroa (La Rioja, Burgos, Soria, España) he distribution of localities and types of dinosaur footprints in the Cameros Basin (La Rioja, Burgos, Soria, Spain) Zubia Monográfico 14:191-210 * X. Pereda Suberbiola, M. Meijide, F. Torcida, J. Welle, C. Fuentes, L. A. Izquierdo, D. Montero, G. Pérez, and V. Urién. 1999. Espinas dermicas del dinosaurio anquilosaurio Polacanthus en las facies Weald de Salas de los Infantes (Burgos, España) ermal spines of the ankylosaurian dinosaur Polacanthus in the Weald facies of Salas de los Infantes (Burgos, Spain) Estudios Geológicos 55:267-272 * F. Ortega, J. J. Moratalla, A.G. Buscalioni, J. S. Sanz, S. Jiménez and J. Valbuena. 1996. Sobre la presencia de un cocodrilo fósil (Crocodylomorpha: Neosuchia: Goniopholis sp.) en la Cuenca de Cameros (Cretácico inferior: Vadillos-San Román de Cameroa, La Rioja). Zubía 14:113-120 Geologic groups of Europe Geologic formations of Spain Lower Cretaceous Series of Europe Cretaceous Spain Barremian Stage Hauterivian Stage Limestone formations Sandstone formations Shale formations Conglomerate formations Alluvial deposits Fluvial deposits Ichnofossiliferous formations Paleontology in Spain Formations Formations