''Riojavenatrix'' (meaning "

La Rioja La Rioja () is an autonomous community and province in Spain, in the north of the Iberian Peninsula. Its capital is Logroño. Other cities and towns in the province include Calahorra, Arnedo, Alfaro, Haro, Santo Domingo de la Calzada, a ...

huntress") is a genus of spinosaurid theropod from 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 Pr ...

Enciso Group The Enciso Group is a geological formation in La Rioja, Spain whose strata date back to the Early Cretaceous.La Rioja La Rioja () is an autonomous community and province in Spain, in the north of the Iberian Peninsula. Its capital is Logroño. Other cities and towns in the province include Calahorra, Arnedo, Alfaro, Haro, Santo Domingo de la Calzada, a ...

, Spain. The type species is ''Riojavenatrix lacustris''. ''Riojavenatrix'' represents one of five known spinosaurid taxa from the Iberian Peninsula, the others being '' Camarillasaurus'', '' Iberospinus'', '' Protathlitis'', and '' Vallibonavenatrix''.

Discovery and naming

Fossils of ''Riojavenatrix'' were discovered in 2005 at the Virgen del Villar-1 site in

, Spain. The holotype of ''Riojavenatrix'' is a fragmentary dorsal vertebra, pelvic girdle, and hindlimb elements that were initially assigned to ''

Baryonyx ''Baryonyx'' () is a genus of theropod dinosaur which lived in the Barremian stage of the Early Cretaceous period, about 130–125 million years ago. The first skeleton was discovered in 1983 in the Smokejack Clay Pit, of Surrey, England, in ...

''. Apparently, all the material belonged to the same individual because it was recovered in association with bones of consistent size and no duplicated elements. The Virgen del Villar-1 site is a part of the

Enciso Group The Enciso Group is a geological formation in La Rioja, Spain whose strata date back to the Early Cretaceous.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 pre ...

–lower

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 ag ...

. The age of this site is likely to be lower Aptian. It makes ''Riojavenatrix'' younger than ''

'', '' Camarillasaurus'', '' Ceratosuchops'', '' Iberospinus'', ''

Riparovenator ''Riparovenator'' ("riverbank hunter") is a genus of baryonychine spinosaurid dinosaur from the Early Cretaceous (Barremian) period of Britain, the type species is ''Riparovenator milnerae''. Discovery and naming Between 2013 and 2017, sp ...

'', and likely '' Vallibonavenatrix''. Although age estimates for ''

Ichthyovenator ''Ichthyovenator'' is a genus of spinosaurid dinosaur that lived in what is now Laos, sometime between 125 and 113 million years ago, during the Aptian stage of the Early Cretaceous period. It is known from fossils collected from the ...

'' and ''

Suchomimus ''Suchomimus'' (meaning "crocodile mimic") is a genus of spinosaurid dinosaur that lived between 125 and 112 million years ago in what is now Niger, during the Aptian to early Albian stages of the Early Cretaceous period. It was named an ...

'' are imprecise, ''Riojavenatrix'' lived around the same time as them. ''Riojavenatrix'' is older than the more derived mid-Cretaceous African and South American spinosaurids. It was named as a new genus of spinosaurid theropod in 2024. The generic name, ''Riojavenatrix'', comes from La Rioja province in Spain, plus the Latin ''venatrix'', meaning "huntress". The specific name, "''lacustris''", is Latin for "from the lake".

Classification

''Riojavenatrix'' was assigned to Spinosauridae based on the features of the pubis and

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

, and more precisely to

Baryonychinae Baryonychinae is an extinct clade or subfamily of spinosaurids from the Early Cretaceous (Valanginian-Albian) of Britain, Portugal, and Niger. In 2021, it consisted of six genera: '' Ceratosuchops'', '' Cristatusaurus'', ''Riparovenator'', ''Su ...

based on the features of the femur,

fibula The fibula or calf bone is a human leg, leg bone on the Lateral (anatomy), lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long ...

, and

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

. Its

astragalus ''Astragalus'' is a large genus of over 3,000 species of herbs and small shrubs, belonging to the legume family Fabaceae and the subfamily Faboideae. It is the largest genus of plants in terms of described species. The genus is native to te ...

also bears some similarity to

Spinosaurinae 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, includ ...

. It is one of the youngest baryonychines known, and the fifth spinosaurid found in the Iberian Peninsula. The following

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

s illustrate the results of the analyzes obtained by the authors of the ''Riojavenatrix'' description using different data sets. The first tree shows several alternative positions. Rauhut & Pol (2021) Mateus & Estraviz-López (2022)

References

{{Taxonbar, from=Q124613493 Early Cretaceous dinosaurs of Europe Spinosaurids Barremian genera Aptian genera Cretaceous Spain Fossil taxa described in 2024