Velocisaurus

Last updated

Velocisaurus
Temporal range: Santonian
~85  Ma
O
S
D
C
P
T
J
K
Pg
N
Velocisaurus holotype left foot.png
A diagram of bones preserved in the holotype left foot of Velocisaurus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Abelisauria
Family: Noasauridae
Subfamily: Noasaurinae
Genus: Velocisaurus
Species:
V. unicus
Binomial name
Velocisaurus unicus
Bonaparte, 1991

Velocisaurus ("swift lizard") is a genus of noasaurid theropod dinosaur from the Late Cretaceous period of Argentina.

Contents

Description

Restoration of Velocisaurus, with head based on that of Masiakasaurus Velocisaurus.jpg
Restoration of Velocisaurus, with head based on that of Masiakasaurus

Velocisaurus was probably around 1.5 meters (4.9 feet) long, based on a tibia length of 14 centimetres (5.5 in). [1] This makes it the smallest noasaurid, after Berthasaura . The foot is unique in that the middle (third) metatarsal has become the main weight-bearing element. Its upper end has thickened whereas the shafts of the adjoining second and fourth metatarsals have thinned considerably. Such a configuration is unknown for other theropods, including birds. Bonaparte explained it as an adaptation for a cursorial (running) lifestyle. The high speed would have been necessary to escape larger theropods; Bonaparte suggested that Velocisaurus was itself an omnivore, as indicated by the fact that the sole claw found, of the fourth toe, was not trenchant but relatively straight. [2]

Velocisaurus can be characterized by several traits unknown in other Abelisauroids. These include: [3]

History of discovery

In 1985 Oscar de Ferrariis and Zulma Brandoni de Gasparini uncovered fossils at Boca del Sapo in Neuquén province of Patagonia from layers of the Bajo de la Carpa Formation, dating from the Santonian. Among them was the right lower hind limb of a small theropod. In 1991 this dinosaur was described and named by José Bonaparte as Velocisaurus unicus. The generic name is derived from Latin velox, "swift", a reference to the fact that the hind leg and foot show adaptations for running. The specific name means "unique" in Latin, referring to the exceptional build of the foot. The genus and species are based on the holotype MUCPv 41, a nearly complete right leg which is part of the collection of the Museo de la Universidad Nacional del Comahue. [2] A somewhat complete left leg, specimen MPCN-PV-370, was described in 2016. [3]

Classification

Bonaparte originally assigned Velocisaurus to a family of its own, the Velocisauridae. A study of theropod relationships by Fernando Novas and Sebastian Apesteguia in 2003 showed that Velocisaurus was a close relative of the strange ceratosaur Masiakasaurus . These two may form a subfamily, the Velocisaurinae. [4] In 2004 this subfamily was assigned to the Noasauridae within the more inclusive Abelisauroidea. [5]

Palaeobiology

In a 2001 study conducted by Bruce Rothschild and other paleontologists, 12 foot bones referred to Velocisaurus were examined for signs of stress fracture, but none were found. [6]

See also

Related Research Articles

<i>Argentinosaurus</i> Late Cretaceous giant sauropod dinosaur genus

Argentinosaurus is a genus of giant sauropod dinosaur that lived during the Late Cretaceous period in what is now Argentina. Although it is only known from fragmentary remains, Argentinosaurus is one of the largest known land animals of all time, perhaps the largest, measuring 30–35 metres (98–115 ft) long and weighing 65–80 tonnes. It was a member of Titanosauria, the dominant group of sauropods during the Cretaceous. It is widely regarded by many paleontologists as the biggest dinosaur ever, and perhaps lengthwise the longest animal ever, though both claims have no concrete evidence yet.

<span class="mw-page-title-main">Ceratosauria</span> Extinct clade of dinosaurs

Ceratosaurs are members of the clade Ceratosauria, a group of dinosaurs defined as all theropods sharing a more recent common ancestor with Ceratosaurus than with birds. The oldest known ceratosaur, Saltriovenator, dates to the earliest part of the Jurassic, around 199 million years ago. Ceratosauria includes three major clades: Ceratosauridae, Noasauridae, and Abelisauridae, found primarily in the Southern Hemisphere. Originally, Ceratosauria included the above dinosaurs plus the Late Triassic to Early Jurassic Coelophysoidea and Dilophosauridae, implying a much earlier divergence of ceratosaurs from other theropods. However, most recent studies have shown that coelophysoids and dilophosaurids do not form a natural group with other ceratosaurs, and are excluded from this group.

<span class="mw-page-title-main">Abelisauridae</span> Extinct family of dinosaurs

Abelisauridae is a family of ceratosaurian theropod dinosaurs. Abelisaurids thrived during the Cretaceous period, on the ancient southern supercontinent of Gondwana, and today their fossil remains are found on the modern continents of Africa and South America, as well as on the Indian subcontinent and the island of Madagascar. Isolated teeth were found in the Late Jurassic of Portugal, and the Late Cretaceous genera Tarascosaurus and Arcovenator have been described in France. Abelisaurids possibly first appeared during the Jurassic period based on fossil records, and some genera survived until the end of the Mesozoic era, around 66 million years ago.

<i>Aucasaurus</i> Extinct genus of dinosaurs

Aucasaurus is a genus of medium-sized abelisaurid theropod dinosaur from Argentina that lived during the Late Cretaceous of the Anacleto Formation. It was smaller than the related Carnotaurus, although more derived in some ways, such as its extremely reduced arms and almost total lack of fingers. The type skeleton is complete to the thirteenth caudal vertebra, and so is relatively well understood, and is the most complete abelisaurid yet described. However, the skull is damaged, causing some paleontologists to speculate that it was involved in a fight prior to death.

Ligabueino is a genus of noasaurid dinosaur named after its discoverer, Italian doctor Giancarlo Ligabue. It is known only from an extremely fragmentary specimen, measuring 79 cm (2.6 ft) long, found in the La Amarga Formation. In spite of initial reports that it was an adult, the unfused vertebrae indicate that the specimen was a juvenile. It was a theropod and lived during the Early Cretaceous Period, in what is now Patagonia. Contrary to initial classifications that placed it as a member of the Noasauridae, Carrano and colleagues found in 2011 that it could only be placed with any confidence in the group Abelisauroidea.

<i>Compsosuchus</i> Extinct genus of dinosaurs

Compsosuchus is a dubious genus of abelisauroid dinosaur from the Late Cretaceous Lameta Formation of India.

<i>Ekrixinatosaurus</i> Extinct genus of dinosaur

Ekrixinatosaurus is a genus of abelisaurid theropod which lived approximately 100 to 97 million years ago during the Late Cretaceous period. Its fossils have been found in Argentina. Only one species is currently recognized, Ekrixinatosaurus novasi, from which the specific name honors of Dr. Fernando Novas for his contributions to the study of abelisaurid theropods, while the genus name refers to the dynamiting of the holotype specimen. It was a large abelisaur, measuring between 6.5 and 8 m in length and weighing 800 kg (1,800 lb).

Genusaurus is a genus of abelisauroid theropod from the Early Cretaceous. Its fossils were found in France. Genusaurus is believed to have lived during the Albian stage, around 112-100 million years ago.

<i>Noasaurus</i> Extinct genus of dinosaurs

Noasaurus is a genus of ceratosaurian theropod dinosaur genus from the late Campanian-Maastrichtian of Argentina. The type and only species is N. leali.

<i>Laevisuchus</i> Extinct genus of dinosaurs

Laevisuchus is a genus of theropod dinosaur from the Late Cretaceous. Its remains were discovered by Charles Alfred Matley near Jabalpur in Maastrichtian "Carnosaur Bed" deposits in the Lameta Formation in Madhya Pradesh, central India, and were named and described by paleontologists Friedrich von Huene and Matley in 1933.

The Huincul Formation is a geologic formation of Late Cretaceous age of the Neuquén Basin that outcrops in the Mendoza, Río Negro and Neuquén Provinces of northern Patagonia, Argentina. It is the second formation in the Río Limay Subgroup, the oldest subgroup within the Neuquén Group. Formerly that subgroup was treated as a formation, and the Huincul Formation was known as the Huincul Member.

<span class="mw-page-title-main">Noasauridae</span> Extinct family of dinosaurs

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 theropods. Their heads, on the other hand, had unusual adaptations depending on the subfamily. 'Traditional' noasaurids, sometimes grouped in the subfamily Noasaurinae, had sharp teeth which splayed outwards from a downturned lower jaw.

Amargatitanis is a genus of dicraeosaurid sauropod dinosaur from the Barremian-age La Amarga Formation of Neuquén, Argentina. It is known from a single, incomplete postcranial skeleton consisting of a partial hindlimb, ischium, and two vertebrae. These remains were unearthed by Argentine paleontologist José Bonaparte in 1983 during an expedition by the Museo Argentino de Ciencias Naturales and later described as a new genus and species, Amargatitanis macni by Sebastián Apesteguía. The genus name comes from the words Amarga, where the fossils were collected, and titanis meaning "titan". Its species name is in reference to the MACN, where the remains are stored.

<i>Austrocheirus</i> Genus of reptiles (fossil)

Austrocheirus is an extinct genus of theropod dinosaur that lived during the Late Cretaceous period. It was named and described by Martin Ezcurra, Federico Agnolin and Fernando Novas in 2010. It contains the type species Austrocheirus isasii. The generic name means "southern hand". The specific epithet honours discoverer and preparator Marcelo Pablo Isasi.

<i>Bonapartenykus</i> A large alvarezsauroid dinosaur

Bonapartenykus is a monospecific genus of alvarezsauroid dinosaur from Argentina that lived during the Late Cretaceous (Campanian-Maastrichtian) in what is now the upper Allen Formation of the Río Negro Province. The type and only species, Bonapartenykus ultimus, is known from a nearly articulated but partial skeleton that was found in close association to two incomplete eggs and several clusters of eggshells belonging to the oogenus Arriagadoolithus. Bonapartenykus was named in 2012 by Federico L. Agnolin, Jaime E. Powell, Fernando E. Novas and Martin Kundrát. Bonapartenykus has an estimated length of 2.5 m (8.2 ft) and weight of 72 kg (159 lb), making it the largest member of the clade Alvarezsauroidea.

Martín Dário Ezcurra is an Argentine palaeontologist naming many extinct genera such as Aerotitan, Lophostropheus and Powellvenator.

<i>Afromimus</i> Extinct genus of dinosaurs

Afromimus is a genus of theropod dinosaur from the Early Cretaceous Elrhaz Formation of Niger. It contains a single species, A. tenerensis, named in 2017 by Paul Sereno from parts of the right leg, vertebrae, and ribs found in the Ténéré Desert. It was originally classified as an ornithomimosaurian, but subsequently it was argued to be an abelisauroid.

Tralkasaurus is a genus of abelisaurid dinosaur from the Huincul Formation from Río Negro Province in Argentina. The type and only species is Tralkasaurus cuyi, named in 2020 by Mauricio Cerroni and colleagues based on an incomplete skeleton. A medium-sized abelisaurid, Tralkasaurus exhibits a conflicting blend of characteristics found among the early-diverging abelisauroids with others that characterize the highly specialized clade Brachyrostra, and thus its position within the clade is poorly-resolved.

<i>Overoraptor</i> Extinct genus of theropod dinosaurs

Overoraptor is an extinct genus of paravian theropod of uncertain affinities from the Late Cretaceous Huincul Formation of Argentinian Patagonia. The genus contains a single species, O. chimentoi, known from several bones of the hands, feet, and hips alongside some vertebrae.

References

  1. Grillo, O. N.; Delcourt, R. (2016). "Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king". Cretaceous Research. 69: 71–89. doi:10.1016/j.cretres.2016.09.001.
  2. 1 2 Bonaparte J.F. (1991). "Los vertebrados fósiles de la Formación Rio Colorado, de la Ciudad de Neuquén y Cercanías, Cretácico Superior, Argentina" [The fossil vertebrates of the Rio Colorado Formation, of the city of Neuquén and surroundings, Upper Cretaceous, Argentina]. Revista del Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" e Instituto Nacional de Investigación de las Ciencias Naturales. Paleontología4: 17-123
  3. 1 2 Egli, F. B.; AgnolÍn, F. L.; Novas, Fernando (2016). "A new specimen of Velocisaurus unicus (Theropoda, Abelisauroidea) from the Paso Córdoba locality (Santonian), Río Negro, Argentina". Journal of Vertebrate Paleontology. 36 (4): e1119156. Bibcode:2016JVPal..36E9156B. doi:10.1080/02724634.2016.1119156. hdl: 11336/46726 . ISSN   0272-4634.
  4. F. AGNOLÍN, F. NOVAS and S. APESTEGUÍA (2003). "Velocisaurids in South America and Madagascar". Ameghiniana40(4): 77R. Museo Argentino de Ciencias Naturales ‘B. Rivadavia’, Av. Ángel Gallardo 470, (1405) Buenos Aires, Argentina
  5. F. E. Novas, F. L. Agnolin, and S. Bandyopadhyay, 2004, "Cretaceous theropods from India: a review of specimens described by Huene and Matley (1933)", Revista del Museo Argentino de Ciencias Naturales, nuevo serie6(1): 67-103
  6. Rothschild, B., Tanke, D. H., and Ford, T. L., 2001, Theropod stress fractures and tendon avulsions as a clue to activity: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 331-336.