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

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

rebbachisaurid Rebbachisauridae is a Family (biology), family of sauropod dinosaurs known from fragmentary fossil remains from the Cretaceous of South America, Africa, North America, Europe and possibly Central Asia. Taxonomy In 1990 sauropod specialist Jack M ...

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 b ...

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

from early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

(late

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a ...

— early

Aptian The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...

stage) deposits of

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

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

skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...

that includes

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

and

postcrania The postcranium ("behind the cranium"; plural: postcrania) or postcranial skeleton in zoology and vertebrate paleontology is the skeleton apart from the skull. The postcranium encompasses the axial skeleton, which includes the entirety of the verte ...

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

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

2011 The year marked the start of a Arab Spring, series of protests and revolutions throughout the Arab world advocating for democracy, reform, and economic recovery, later leading to the depositions of world leaders in Tunisia, Egypt, and Yemen ...

and the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

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 o ...

.''

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 in Burgos province between La Rioja, Soria and Burgos city in Spain. It is hilly with many foothills and mountains. The mountain range Sierra de la Demanda with the black lagoon, La Laguna Negra, ...

in Burgos, Spain.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 Spinosauridae (or spinosaurids) is a clade or family of tetanuran theropod dinosaurs comprising ten to seventeen known genera. Spinosaurid fossils have been recovered worldwide, including Africa, Europe, South America, and Asia. Their remains have ...

, small

ornithopods Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (). They represent one of the most successful groups of herbivore, herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and rel ...

, 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 (: 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 saurop ...

, 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 ha ...

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 the city of Naples. It is the largest of the Phlegrean Islands. Although inhabited since the Bronze Age, as a Ancient G ...

, 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 Academ ...

.'' 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 Rebbachisauridae Dinosaur genera Barremian dinosaurs Fossil taxa described in 2011 Dinosaurs of Spain