''Paraxenisaurus'' (meaning "strange lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

deinocheirid Deinocheiridae is a family (biology), family of ornithomimosaurian dinosaurs, living in Asia and the Americas from the Albian until the Maastrichtian. The family was originally named by Halszka Osmólska and Roniewicz in 1970 in paleontology, 197 ...

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally ...

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 ...

that lived in what is now Mexico during the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

stage of the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

Period, 73 to 72.1 million years ago.

Discovery and naming

During the 1990s, ornithomimosaur

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

were discovered at three sites in the

Cerro del Pueblo Formation The Cerro del Pueblo Formation is a geological Formation (geology), formation in Coahuila, Mexico whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel et al., ...

Coahuila Coahuila (), formally Coahuila de Zaragoza (), officially the Free and Sovereign State of Coahuila de Zaragoza ( es, Estado Libre y Soberano de Coahuila de Zaragoza), is one of the 32 states of Mexico. Coahuila borders the Mexican states of N ...

state. Two decades later, these remains were identified as belonging to a distinct North American taxon. In 2020, they were named and described by Mexican

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...

s Claudia Inés Serrano-Brañas, Belinda Espinosa-Chávez, Sarah Augusta Maccracken, Cirene Gutiérrez-Blando, Claudio de León-Dávila and José Flores Ventura. 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( ...

''Paraxenisaurus normalensis''. The generic name is derived from the Greek ''paráxenos'', "strange". The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

is after the Benemérita Escuela Normal de Coahuila, a teacher training institution, where the fossils had been deposited. They include the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

BENC 2/2-001, a partial skeleton lacking the skull. Four additional specimens were referred, from separate individuals. The material contains

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

of the backbone, as well as a thighbone, an

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 ...

and hand, most notably a manual claw, and foot elements. Paraxenisaurus Manual Claw

Description

Paraxenisaurus normalensis as Deinocheirid

Based on the fossil elements of the holotype, the specimen was an adult. The length of ''Paraxenisaurus'' has been estimated at , and its weight at .

Classification

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis recovered ''Paraxenisaurus'' as a member of the Deinocheiridae, in a polytomy with ''

Deinocheirus ''Deinocheirus'' ( ) is a genus of large ornithomimosaur that lived during the Late Cretaceous around 70 million years ago. In 1965, a pair of large arms, shoulder girdles, and a few other bones of a new dinosaur were first discovered in the Ne ...

'' and '' Garudimimus''. It would then represent the first deinocheirid dinosaur found in North America.

Paleoecology

Known from the

, ''Paraxenisaurus'' lived alongside ''

Coahuilaceratops ''Coahuilaceratops'' (meaning "Coahuila horn face") is a genus of herbivorous ceratopsian dinosaur. It is a chasmosaurine ceratopsian which lived during the Late Cretaceous period (late Campanian stage) in what is now southern Coahuila in northe ...

'', '' Latirhinus'', and ''

Velafrons ''Velafrons'' (meaning "sailed forehead") is a genus of lambeosaurine hadrosaurid dinosaur from the Late Cretaceous of Mexico. It is known from a mostly complete skull and partial skeleton of a juvenile individual, with a bony crest on the for ...

,'' and other undescribed ornithomimosaurs. This area was most likely a coastal plain during the Late Cretaceous.

References

Late Cretaceous dinosaurs of North America Fossil taxa described in 2020 Ornithomimosaurs Campanian life Fossils of Mexico {{Theropod-stub