''Demandasaurus'' (meaning " Demanda lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of rebbachisaurid

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their bo ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

from early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

(late

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...

– early

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

stage) deposits of

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

. ''Demandasaurus'' is known from an incomplete but associated

skeleton A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...

that includes

cranial Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

and

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

l remains. It was collected from the Castrillo de la Reina Formation in

Burgos Province The Province of Burgos is a province of northern Spain, in the northeastern part of the autonomous community of Castile and León. It is bordered by the provinces of Palencia, Cantabria, Vizcaya, Álava, La Rioja, Soria, Segovia, and Valladolid. ...

. It was first named by Fidel Torcida Fernández-Baldor, José Ignacio Canudo, Pedro Huerta, Diego Montero, Xabier Pereda Suberbiola and Leonardo Salgado in

2011 File:2011 Events Collage.png, From top left, clockwise: a protester partaking in Occupy Wall Street heralds the beginning of the Occupy movement; protests against Libyan dictator Muammar Gaddafi, who was killed that October; a young man celebrate ...

and the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''Demandasaurus darwini''.

Description

It has a series of singular characteristics that allow this differentiation as a new genus and species. For example, teeth with a special ornamentation of ridges in its enamel, cervical vertebrae with bone structures that are not present in other dinosaurs, neural arches of the dorsal vertebrae crossed entirely by two pneumatic fossae. The rounded shape of its snout also contrasts with the most square contour snouts of the rest of the diplodocoids and especially its close relative ''

Nigersaurus ''Nigersaurus'' is a genus of rebbachisaurid sauropod dinosaur that lived during the middle Cretaceous period, about 115 to 105 million years ago. It was discovered in the Elrhaz Formation in an area called Gadoufaoua, in Niger. Fossils of th ...

.''

History and naming

''Demandasaurus'' was first collected between 2002 and 2004 by the Archaeological−Palaeontological Group of Salas de los Infantes at Tenadas de los Vallejos II, a fossil locality north of

Salas de los Infantes Salas de los Infantes is a municipality and city located in Burgos Province between La Rioja, Soria and Burgos in Spain. It is hilly with many foothills and mountains. The mountain range Sierra de la Demanda with the black lagoon, ''La Laguna Ne ...

Burgos, Spain Burgos () is a city in Spain located in the autonomous community of Castile and León. It is the capital and most populated municipality of the province of Burgos. Burgos is situated in the north of the Iberian Peninsula, on the confluence of ...

.Fernández-Baldor, F. T. (2012). ''Sistemática, filogenia y análisis paleobiogeográfico de demandasaurus darwini (sauropoda, rebbachisauridae) del Barremiense superior-Aptiense de Burgos: España'' (Doctoral dissertation, Universidad de Zaragoza). The strata at the site comes from the Upper Barremian- Lower Aptian of the Castrillo de la Reina Formation, and the ''Demandasaurus'' fossils were found alongside fossils of

spinosaurids The Spinosauridae (or spinosaurids) are a clade or Family (taxonomy), family of tetanuran theropod dinosaurs comprising ten to seventeen known genera. They came into prominence during the Cretaceous Geological period, period. Spinosaurid fossils h ...

, small

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

, and a crocodilian. About 810 fossils were collected at the site, most of them pertaining to the type skeleton of ''Demandasaurus.'' The skeleton (MDS−RVII assorted) consists of: premaxillae, left dentary, six isolated teeth, 3

cervical vertebrae In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...

, 5 cervical ribs, 2 dorsals, 9 dorsal ribs, 19 caudal vertebrae, 9

haemal arch A haemal arch also known as a chevron, is a bony arch on the ventral side of a tail vertebra of a vertebrate. The canal formed by the space between the arch and the vertebral body is the haemal canal. A spinous ventral process emerging from the hae ...

es of chevrons,

ischia Ischia ( , , ) is a volcanic island in the Tyrrhenian Sea. It lies at the northern end of the Gulf of Naples, about from Naples. It is the largest of the Phlegrean Islands. Roughly trapezoidal in shape, it measures approximately east to west ...

, and left femur. The skeleton was described as the holotype of a new taxon, ''Demandasaurus darwini'', in 2011 by Fernández−Baldor and colleagues in the ''

Acta Palaeontologica Polonica ''Acta Palaeontologica Polonica'' is a quarterly peer-reviewed open access scientific journal of paleontology and paleobiology. It was established by Roman Kozłowski in 1956. It is published by the Institute of Paleobiology of the Polish Academy ...

.'' The genus name comes from the Demanda mountain chain, which was where the type locality was located, and the specific name is after famous naturalist Charles Darwin. The taxon was later described in detail in the thesis of Torcida Fernández-Baldor in 2012.

Classification and evolution

''Demandasaurus'' is the only rebbachisaurid described from Spain. ''Demandasaurus'' is also one of the few known European rebbachisaurids, being the first recognized, as the group was formerly known only in Africa and South America.Torcida Fernández-Baldor, F., & Canudo, J. I. (2013). Rebbachisauridae: the European exception. ''Libro de resúmenes Abstract book'', 31. This taxon has a high paleobiogeographic interest due to its close kinship relationship with the African ''Nigersaurus'' it has been an argument contributed to develop the hypothesis of an African origin of ''Demandasaurus''. Likewise, the appearance in Europe of ''Demandasaurus'', is proof of the existence of a physical connection, an intercontinental bridge, between the two continents in that age, although it did not occur permanently.

References

{{Taxonbar, from=Q1932503 Rebbachisaurids Barremian life Early Cretaceous dinosaurs of Europe Cretaceous Spain Fossils of Spain Fossil taxa described in 2011