Quilmesaurus
Encyclopedia
Quilmesaurus is a genus
of theropod dinosaur
from the Patagonia
n Upper Cretaceous
(Campanian
stage
), a time when South American theropod assemblages were dominated by abelisaurids and carcharodontosaurs. However, the morphology of Quilmesaurus suggests it may have been a tetanuran. Though only portions of the right leg have been recovered, this animal is estimated to have measured 5–6 meters (16–20 feet) in length. The holotype
(MPCA-PV-100; Museo Provincial Carlos Ameghino) consists of the distal half of the right femur
and a complete right tibia
collected from the Allen Formation
(Campanian
-Maastrichtian
), Malarge Group, Neuquén Basin, at Salitral Ojo de Aqua, 40 kilometers south of Roca City, Río Negro Province, northern Argentina
. The specimen came from the fluvial
sandstone
s at the bottom of the Allen Formation and was collected in the late 1980s by a field crew from the Universidad Nacional Tucumán.
Quilmesaurus curriei is distinguished by a highly specialized knee joint. The femur possess a strong, well-developed mediodistal crest, and the tibia has a hooked cnemial crest. There is evidently no fusion of the proximal tarsal
s, and the lateral maleous projects distally more than the internal maleous, presenting an asymmetrical profile. The presence of a notch in the distal articular surface of the tibia was cited by Coria (2001) as evidence of a possible relationship with basal tetanurans. This taxon
is notable as the youngest record for a non-avian
theropod from Patagonia.
The genus name derives from the Quilme
, a Native American people
, and the species is named in honor of Dr. Phillip J. Currie, a Canadian
theropod specialist. Other theropod material has been recovered from within these same strata
and has also provisionally been referred to the Tetanurae
(Coria et Salgado, 2005). Other dinosaur remains recovered from the Allen Formation include titanosaur
s (Aeolosaurus
), a lambeosaurine hadrosaur, a nodosaurid, and dinosaur egg
s.
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 theropod 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 Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
n Upper 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...
(Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
), a time when South American theropod assemblages were dominated by abelisaurids and carcharodontosaurs. However, the morphology of Quilmesaurus suggests it may have been a tetanuran. Though only portions of the right leg have been recovered, this animal is estimated to have measured 5–6 meters (16–20 feet) in length. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
(MPCA-PV-100; Museo Provincial Carlos Ameghino) consists of the distal half of the right femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
and a complete right tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
collected from the Allen Formation
Allen Formation
The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous The Allen Formation is a geological formation in Argentina whose strata date back to the...
(Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
-Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
), Malarge Group, Neuquén Basin, at Salitral Ojo de Aqua, 40 kilometers south of Roca City, Río Negro Province, northern 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...
. The specimen came from the fluvial
Fluvial
Fluvial is used in geography and Earth science to refer to the processes associated with rivers and streams and the deposits and landforms created by them...
sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
s at the bottom of the Allen Formation and was collected in the late 1980s by a field crew from the Universidad Nacional Tucumán.
Quilmesaurus curriei is distinguished by a highly specialized knee joint. The femur possess a strong, well-developed mediodistal crest, and the tibia has a hooked cnemial crest. There is evidently no fusion of the proximal tarsal
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
s, and the lateral maleous projects distally more than the internal maleous, presenting an asymmetrical profile. The presence of a notch in the distal articular surface of the tibia was cited by Coria (2001) as evidence of a possible relationship with basal tetanurans. This taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
is notable as the youngest record for a non-avian
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...
theropod from Patagonia.
The genus name derives from the Quilme
Quilmes (tribe)
The Quilmes people were an indigenous tribe of the Diaguita group settled in the western subandean valleys of today’s Tucumán province, in northwestern Argentina. They fiercely resisted the Inca invasions of the 15th century, and continued to resist the Spaniards for 130 years, until being defeated...
, a Native American people
Indigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...
, and the species is named in honor of Dr. Phillip J. Currie, a Canadian
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
theropod specialist. Other theropod material has been recovered from within these same strata
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
and has also provisionally been referred to the Tetanurae
Tetanurae
Tetanurae, or "stiff tails", is a clade that includes most theropod dinosaurs, as well as birds. Tetanurans first appear during the early or middle Jurassic Period.-Definition:...
(Coria et Salgado, 2005). Other dinosaur remains recovered from the Allen Formation include titanosaur
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...
s (Aeolosaurus
Aeolosaurus
Aeolosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. Like most sauropods, it would have been a quadrupedal herbivore with a long neck and tail...
), a lambeosaurine hadrosaur, a nodosaurid, and dinosaur egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s.