Santanaraptor
Encyclopedia
Santanaraptor is a genus
of theropod dinosaur
that lived in South America
during the Albian
or Aptian
stage of the Early Cretaceous
, about 108 million years ago. Known from a partial juvenile specimen recovered with mineralized soft tissue
, which was unearthed in 1996 from the Santana Formation of northeastern Brazil
. While primarily known from hindquarter elements, the individual represented by the fossil may have reached 1.25 metres (4.1 ft) in length. Santanaraptor is thought by some paleontologists to be the first tyrannosauroid known from Gondwana
, but it may be a more basal coelurosaur.
(MN
4802-V) consists of 3 caudal vertebrae with chevrons, ischia, femora, tibia, fibula, pes, and soft tissue. The fossil
ized tissue includes a thin epidermis
, muscle
fibers, and possibly blood vessel
s.
The type species
is S. placidus, first described by Kellner in 1999. The species epithet refers to Placido Cidade Nuvens, who founded the Museo de Santana do Cariri.
Santanaraptor was originally thought to be a maniraptoran theropod when it was first discovered. However, it is now thought to be a basal coelurosaur based on several features present on the femur
. Santanaraptor may have been closely related to Ornitholestes
, an earlier coelurosaur of the Late Jurassic
, based on similarities in the ischium, a bone of the pelvis
.
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...
that lived in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
during the Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
or Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
stage of the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
, about 108 million years ago. Known from a partial juvenile specimen recovered with mineralized soft tissue
Mineralized tissues
Mineralized tissues are biological tissues that incorporate minerals into soft matrices. Typically these tissues form a protective shield or structural support...
, which was unearthed in 1996 from the Santana Formation of northeastern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. While primarily known from hindquarter elements, the individual represented by the fossil may have reached 1.25 metres (4.1 ft) in length. Santanaraptor is thought by some paleontologists to be the first tyrannosauroid known from Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
, but it may be a more basal coelurosaur.
Classification
The holotypeHolotype
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...
(MN
National Museum of Brazil
The National Museum of Brazil is a centenarian museum and research institution, located in the Quinta da Boa Vista park in the city of Rio de Janeiro, Brazil.-History:...
4802-V) consists of 3 caudal vertebrae with chevrons, ischia, femora, tibia, fibula, pes, and soft tissue. The fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
ized tissue includes a thin epidermis
Epidermis (zoology)
The Epidermis is an epithelium that covers the body of an eumetazoan . Eumetazoa have a cavity lined with a similar epithelium, the gastrodermis, which forms a boundary with the epidermis at the mouth.Sponges have no epithelium, and therefore no epidermis or gastrodermis...
, muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
fibers, and possibly blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
s.
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 S. placidus, first described by Kellner in 1999. The species epithet refers to Placido Cidade Nuvens, who founded the Museo de Santana do Cariri.
Santanaraptor was originally thought to be a maniraptoran theropod when it was first discovered. However, it is now thought to be a basal coelurosaur based on several features present on the 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...
. Santanaraptor may have been closely related to Ornitholestes
Ornitholestes
Ornitholestes was a small theropod dinosaur of the late Jurassic of Western Laurasia . To date, it is known only from a single partial skeleton, and badly crushed skull found at the Bone Cabin Quarry near Medicine Bow, Wyoming, in 1900...
, an earlier coelurosaur of the Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
, based on similarities in the ischium, a bone of the pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
.