Alvarezsaurus
Encyclopedia
Alvarezsaurus is a genus
of small alvarezsaurid
dinosaur
from the Late Cretaceous
period of Argentina
, approximately 86 - 83 million years ago. Estimates suggest that it measured about 2 meters in length and weighed approximately 20 kg. It was found in the Bajo de la Carpa Formation
and was named by paleontologist José Bonaparte
in 1991 after the historian Don Gregorio Alvarez.
The type species
is A. calvoi. It was biped
al, had a long tail and its leg structure suggests that it was a fast runner. It may have been insectivorous
and was basal
to better-known members of its family, such as Mononykus
and Shuvuuia
. It has been alternately classified with both non-avian
theropod dinosaurs and early bird
s.
television series Dinosaur Planet, which speculated that it was a predator of young Saltasaurus
, though these species did not exist at the same time, Alvarezsaurus being about 5 million years older than Saltasaurus.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of small alvarezsaurid
Alvarezsauridae
Alvarezsauridae is an enigmatic family of small, long-legged running dinosaurs. Although originally thought to represent the earliest known flightless birds, a consensus of recent work suggests that they are primitive members of the Maniraptora. Other work found them to be the sister group to the...
dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period of Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, approximately 86 - 83 million years ago. Estimates suggest that it measured about 2 meters in length and weighed approximately 20 kg. It was found in the Bajo de la Carpa Formation
Bajo de la Carpa Formation
The Bajo de la Carpa Formation is a geologic formation that outcrops in Patagonia, in the provinces of Río Negro and Neuquén, Argentina. It is the first of two formations belonging to the Río Colorado Subgroup within the Neuquén Group...
and was named by paleontologist José Bonaparte
José Bonaparte
José Fernando Bonaparte, Ph.D. , is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria...
in 1991 after the historian Don Gregorio Alvarez.
The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
is A. calvoi. It was biped
Biped
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...
al, had a long tail and its leg structure suggests that it was a fast runner. It may have been insectivorous
Insectivore
An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects....
and was basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
to better-known members of its family, such as Mononykus
Mononykus
Mononykus was a theropod dinosaur from late Cretaceous Mongolia with long, skinny legs. It moved about on two legs, was very nimble, and could run at high speeds, something that would have been useful in the open desert plains where it lived...
and Shuvuuia
Shuvuuia
Shuvuuia is a genus of bird-like theropod dinosaur from the late Cretaceous period of Mongolia. It is a member of the family Alvarezsauridae, small coelurosaurian dinosaurs which are characterized by short but powerful forelimbs specialized for digging. The type species is Shuvuuia deserti, or...
. It has been alternately classified with both non-avian
Avian
Avian may refer to:* Bird* Avian , an American metal band* AVIAN International, major international company headquartered in Hungary.* Aviano or Avian, an Italian city...
theropod dinosaurs and early bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s.
In popular culture
Alvarezsaurus was featured in the Discovery ChannelDiscovery Channel
Discovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...
television series Dinosaur Planet, which speculated that it was a predator of young Saltasaurus
Saltasaurus
Saltasaurus is a genus of titanosaurid sauropod dinosaur of the Late Cretaceous Period. Relatively small among sauropods, though still massive by the standards of modern creatures, Saltasaurus was characterized by a diplodocid-like head...
, though these species did not exist at the same time, Alvarezsaurus being about 5 million years older than Saltasaurus.