Cedrorestes
Encyclopedia
Cedrorestes is a genus
of iguanodontian dinosaur
from the Early Cretaceous
of Utah
. It is based on an incomplete skeleton which was found in the Barremian
-age Yellow Cat Member of the Cedar Mountain Formation.
DMNH
47994, a partial skeleton including rib fragments, a sacrum
, the left ilium
and a portion of the right, a right thighbone
, the right third metatarsal, and fragments of ossified tendons. These remains were recovered from near the top of the Yellow Cat Member of the Cedar Mountain Formation, in east-central Utah. They were found scattered in a calcareous
mudstone
, and showed evidence of pre-burial damage, from weathering or trampling.
This genus can be told apart from other iguanodontian ornithopod
s by its combination of a tall ilium, as is present in Iguanodon
-like ornithopods, with a large lateral
bony process above and behind the acetabulum
and joint surface for the ischium, as is seen in hadrosaurids. David Gilpin and his coauthors, who described the specimen, noted that the lateral process has been considered diagnostic for hadrosaurids, and interpreted the combination of anatomical characteristics in Cedrorestes as evidence that the genus was close to the division between hadrosaurids and iguanodontids. They placed their new genus in Hadrosauridae, as the earliest known hadrosaurid.
The etymology of the generic name is, from Latin
, cedrus (cedr-); "cedar" + Greek
oros-; "mountain", after the Cedar Mountain formation, where the fossil was found + Greek suffix ending -etes; "dweller". The specific epithet crichtoni is after Michael Crichton
, author of Jurassic Park and The Lost World.
n theropod Nedcolbertia
, the dromaeosaurid Utahraptor
, brachiosaurid sauropod Cedarosaurus
, and heavily armored ankylosaurid Gastonia
.
Whether a basal hadrosaurid or derived
non-hadrosaurid iguanodontian, Cedrorestes would have been a large herbivore
capable of moving both bipedally or on all fours
. The structure of its hip indicates that it had hadrosaurid-like leg muscle
s, but the functional significance of the changes in leg muscles from the iguanodontian layout to the hadrosaurid layout, and resulting differences in movement (if any), are not yet understood. Detailed interpretations of the paleobiology of Cedrorestes must wait for the discovery of more extensive remains.
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 iguanodontian 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 Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
of Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
. It is based on an incomplete skeleton which was found in the Barremian
Barremian
The Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
-age Yellow Cat Member of the Cedar Mountain Formation.
Discovery and history
Cedrorestes is based onHolotype
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...
DMNH
Denver Museum of Nature and Science
The Denver Museum of Nature & Science is a municipal natural history and science museum in Denver, Colorado. It is a resource for informal science education in the Rocky Mountain region. A variety of exhibitions, programs, and activities help museum visitors learn about the natural history of...
47994, a partial skeleton including rib fragments, a sacrum
Sacrum
In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...
, the left ilium
Ilium (bone)
The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...
and a portion of the right, a right thighbone
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....
, the right third metatarsal, and fragments of ossified tendons. These remains were recovered from near the top of the Yellow Cat Member of the Cedar Mountain Formation, in east-central Utah. They were found scattered in a calcareous
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
, and showed evidence of pre-burial damage, from weathering or trampling.
This genus can be told apart from other iguanodontian ornithopod
Ornithopod
Ornithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American...
s by its combination of a tall ilium, as is present in Iguanodon
Iguanodon
Iguanodon is a genus of ornithopod dinosaur that lived roughly halfway between the first of the swift bipedal hypsilophodontids and the ornithopods' culmination in the duck-billed dinosaurs...
-like ornithopods, with a large lateral
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
bony process above and behind the acetabulum
Acetabulum
The acetabulum is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.-Structure:...
and joint surface for the ischium, as is seen in hadrosaurids. David Gilpin and his coauthors, who described the specimen, noted that the lateral process has been considered diagnostic for hadrosaurids, and interpreted the combination of anatomical characteristics in Cedrorestes as evidence that the genus was close to the division between hadrosaurids and iguanodontids. They placed their new genus in Hadrosauridae, as the earliest known hadrosaurid.
The etymology of the generic name is, from Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
, cedrus (cedr-); "cedar" + Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
oros-; "mountain", after the Cedar Mountain formation, where the fossil was found + Greek suffix ending -etes; "dweller". The specific epithet crichtoni is after Michael Crichton
Michael Crichton
John Michael Crichton , best known as Michael Crichton, was an American best-selling author, producer, director, and screenwriter, best known for his work in the science fiction, medical fiction, and thriller genres. His books have sold over 200 million copies worldwide, and many have been adapted...
, author of Jurassic Park and The Lost World.
Paleoecology and paleobiology
The Yellow Cat Member of the Cedar Mountain Formation is known for its dinosaurs, including the small coelurosauriaCoelurosauria
Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. In the past, it was used to refer to all small theropods, although this classification has been abolished...
n theropod Nedcolbertia
Nedcolbertia
Nedcolbertia is a genus of dinosaur from the Early Cretaceous Period. It was a coelurosaur which lived in North America during the Barremian. Kirkland, Britt, Madsen and Burge in 1995 reported its discovery in the basal Cedar Mountain Formation in Utah. The type species, N...
, the dromaeosaurid Utahraptor
Utahraptor
Utahraptor is a genus of theropod dinosaurs, including the largest known members of the family Dromaeosauridae. Fossil specimens date to the upper Barremian stage of the early Cretaceous period...
, brachiosaurid sauropod Cedarosaurus
Cedarosaurus
Cedarosaurus was a nasal-crested macronarian dinosaur genus from the Early Cretaceous Period . It was a sauropod which lived in what is now Utah...
, and heavily armored ankylosaurid Gastonia
Gastonia (dinosaur)
Gastonia is a genus of nodosaurid dinosaur from the Early Cretaceous of North America, around 125 million years ago. Closely related to Polacanthus, it has a sacral shield and large shoulder spikes. It is also the first polacanthine dinosaur to have been mounted for display at the Denver Museum of...
.
Whether a basal hadrosaurid or derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
non-hadrosaurid iguanodontian, Cedrorestes would have been a large herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
capable of moving both bipedally or on all fours
Quadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
. The structure of its hip indicates that it had hadrosaurid-like leg 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...
s, but the functional significance of the changes in leg muscles from the iguanodontian layout to the hadrosaurid layout, and resulting differences in movement (if any), are not yet understood. Detailed interpretations of the paleobiology of Cedrorestes must wait for the discovery of more extensive remains.