''Vespersaurus'' (meaning "western lizard") is a genus of

noasaurid Noasauridae is an extinct family of theropod dinosaurs belonging to the group Ceratosauria. They were closely related to the short-armed abelisaurids, although most noasaurids had much more traditional body types generally similar to other ther ...

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 c ...

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 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'', the ...

Rio Paraná Formation in the

Paraná Basin The Paraná Basin ( pt, Bacia do Paraná, es, Cuenca del Paraná) is a large cratonic sedimentary basin situated in the central-eastern part of South America. About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande d ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. The type and only species is ''V. paranaensis'', which would have lived in the giant prehistoric Botucatu Desert.

Etymology

The generic name is derived from the Latin "vesper," meaning "evening/west," in reference to the town

Cruzeiro do Oeste Cruzeiro do Oeste is a municipality in the state of Paraná in the Southern Region of Brazil. See also *List of municipalities in Paraná This is a list of the municipalities in the state of Paraná (PR), located in the South Region of Brazil. ...

("Western Cross") near which the fossils were found, and the Greek "sauros," meaning "lizard." The specific name refers to the

Paraná state Paraná, Paranã or Parana may refer to: Geology *Paraná Basin, a sedimentary basin in South America Places In Argentina * Paraná, Entre Ríos, a city * Paraná Department, a part of Entre Ríos Province * Paraná, Buenos Aires, a settlemen ...

Discovery and naming

After the discovery of numerous skeletons of the pterosaurs ''

Caiuajara ''Caiuajara'' is an extinct genus of tapejarid pterosaur from the Late Cretaceous period ( Santonian stage) of Brazil. It is known from a single type species, ''Caiuajara dobruskii''. Discovery and naming In 1971, the labourers Alexandre Dobr ...

'' and ''

Keresdrakon ''Keresdrakon'' is an extinct genus of tapejaromorph pterosaur from the Goio-Erê Formation of Brazil, which dates back to the Late Cretaceous period (Turonian-Campanian stages), 94 to 71 million years ago. ''Keresdrakon'' contains a single spe ...

'' at the Cemitério dos Pterossauros site near Cruzeiro do Oeste, the remains of small theropods were uncovered between 2011 and 2015. One of these was named and described in 2019 as ''Vespersaurus''. The holotype, MPCO.V 0065d, was recovered from the

period, found on dark red

sandstones 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) b ...

in the Rio Paraná Formation in the

. Footprints belonging to ''Vespersaurus'' or a similar one-toed

were discovered near Cruzeiro do Oeste as early as the 1970s.

Description

Cranial and dental remains of Vespersaurus

The

taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...

is notable for its distinct, functionally monodactyl foot anatomy, where the singularly large third digit would have borne most of the weight while walking. Based on the proportions of its

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 several ...

remains (MPCO.V 0065d), ''Vespersaurus'' was a small theropod with an estimated body length of . This makes it comparable in size to ''

Noasaurus ''Noasaurus'' ("Northwestern Argentina lizard") is a genus of ceratosaurian theropod dinosaur genus from the late Campanian-Maastrichtian (Late Cretaceous) of Argentina. The type and only species is ''N. leali''. Discovery and naming In the m ...

'' and ''

Masiakasaurus ''Masiakasaurus'' is a genus of small predatory noasaurid theropod dinosaurs from the Late Cretaceous of Madagascar. In Malagasy, ''masiaka'' means "vicious"; thus, the genus name means "vicious lizard". The type species, ''Masiakasaurus knopfl ...

.'' The estimated body mass of ''Vespersaurus'' is , nearly that of the ornithischians '' Jeholosaurus shangyuanensis'' and ''

Gasparinisaura cincosaltensis ''Gasparinisaura'' (meaning "Gasparini's lizard") is a genus of herbivorous ornithopod dinosaur from the Late Cretaceous. The first fossils of ''Gasparinisaura'' were found in 1992 near Cinco Saltos in Río Negro Province, Argentina. The type sp ...

''.

References

Abelisaurs Late Cretaceous dinosaurs of South America Cretaceous Brazil Fossils of Brazil Fossil taxa described in 2019 Paraná Basin {{theropod-stub