Claosaurus
Encyclopedia
Claosaurus is a genus
of primitive hadrosaurid
(duck-billed dinosaur
) that lived during the Late Cretaceous
Period (Santonian
).
Evidence of its existence was first found near the Smoky Hill River
in Kansas
, USA in the form of partial skull fragments and as an articulated postcranial skeleton. Originally named Hadrosaurus agilis (Marsh, 1872), it was placed in a new genus and renamed Claosaurus agilis in 1890 when major differences between this specimen and Hadrosaurus
came to light.
Claosaurus had a slender body and slim feet, with long legs, small arms, and a long, stiff tail. It probably grew to a length of about 3.5 meters (12 to 16 feet) and weighed roughly 475 kg.
It appears to have walked on its hind legs, dropping to all fours only to graze. Like other hadrosaurs, it was an herbivore
.
Original, as described by Marsh, 1872:
1. Notice of a new species of Hadrosaurus; by O. C. MARSH. Among the Reptilian remains obtained by the Yale College party during the past summer (1871) was the greater part of a skeleton of a small Hadrosaurus, discovered by the writer in the blue Cretaceous shale near the Smoky Hill River, in Western Kansas. This species was somewhat smaller than H. minor Marsh, from New Jersey
, and hardly more than one-third the bulk of H. Foulkei of Leidy. It was of more slender proportions, with the tail much elongated. The cervical vertebra are proportionally shorter than in H. Foulkei, and the caudals appear more compressed, Some of the distal caudals have a longitudinal ridge on the lateral surface. The sacrum
, which is composed of six confluent vertebræ is 414 mm. in length. The first caudal vertebra is 62 mm. in length. The feet are nearly entire, and are proportionally more slender than the known remains of the other species would indicate. The third metatarsal is 235 mm. in length, and 77 mm. in transverse diameter at its distal end. This species, which may be called Hadrosaurus agilis, will be fully described in this Journal at an early day.
Yale
College, New Haven, March 19, 1872.
In 1892, Marsh named a second species, C. annectens. This species later was reassigned to Anatosaurus and then Edmontosaurus
, where it is currently. G. R. Wieland named third species C. affinis in 1903, which he compared to C. annectens. C. affinis was founded on remains from the Pierre Shale
of South Dakota
, found in association with remains of the giant sea turtle Archelon
. At some point after its description, the fragmentary remains were mixed up with the original remains of C. agilis, and a toe bone from C. agilis was accidentally thought to be the only part of the holotype
remains that could be located. This was corrected by Joseph Gregory in 1948, who found three toe bones from the right foot of a large hadrosaur in the Yale collections that had comparable preservation to the Pierre Shale turtle remains and were associated with labels in Wieland's handwriting. Gregory found the toe bones to be very similar in size to the corresponding bones of Marsh's Claosaurus annectens, but did not reassign the species due to its much older age and fragmentary remains. "C. affinis" was considered a dubious
hadrosaur in the 2004 review by Jack Horner and colleagues. They reported its type material as lost, although they also reported these remains as only including a single toe bone, instead of the three toe bones of Gregory.
Reports of gastrolith
s, or stomach stones, in Claosaurus are actually based on a probable double misidentification. First, the specimen is actually of Edmontosaurus annectens
. Barnum Brown
, who discovered the specimen in 1900, referred to it as Claosaurus, because E. annectens was thought to be a species of Claosaurus at the time. Additionally, it is more likely that the supposed gastroliths represent gravel washed in during burial.
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 primitive hadrosaurid
Hadrosaurid
Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. They were common herbivores in the Upper Cretaceous Period of what are now Asia, Europe and North America. They are descendants of the Upper...
(duck-billed 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 during the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
Period (Santonian
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...
).
Smoky Hill River
The Smoky Hill River is a river in the central Great Plains of North America, running through the U.S. states of Colorado and Kansas.-Names:The Smoky Hill gets its name from the Smoky Hills region of north-central Kansas through which it flows...
in Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
, USA in the form of partial skull fragments and as an articulated postcranial skeleton. Originally named Hadrosaurus agilis (Marsh, 1872), it was placed in a new genus and renamed Claosaurus agilis in 1890 when major differences between this specimen and Hadrosaurus
Hadrosaurus
Hadrosaurus is a valid genus of hadrosaurid dinosaur. In 1858, a skeleton of a dinosaur from this genus was the first dinosaur skeleton known from more than isolated teeth to be found in North America. In 1868, it became the first ever mounted dinosaur skeleton...
came to light.
Claosaurus had a slender body and slim feet, with long legs, small arms, and a long, stiff tail. It probably grew to a length of about 3.5 meters (12 to 16 feet) and weighed roughly 475 kg.
It appears to have walked on its hind legs, dropping to all fours only to graze. Like other hadrosaurs, it was an 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...
.
Original, as described by Marsh, 1872:
1. Notice of a new species of Hadrosaurus; by O. C. MARSH. Among the Reptilian remains obtained by the Yale College party during the past summer (1871) was the greater part of a skeleton of a small Hadrosaurus, discovered by the writer in the blue Cretaceous shale near the Smoky Hill River, in Western Kansas. This species was somewhat smaller than H. minor Marsh, from New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
, and hardly more than one-third the bulk of H. Foulkei of Leidy. It was of more slender proportions, with the tail much elongated. The cervical vertebra are proportionally shorter than in H. Foulkei, and the caudals appear more compressed, Some of the distal caudals have a longitudinal ridge on the lateral surface. The 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...
, which is composed of six confluent vertebræ is 414 mm. in length. The first caudal vertebra is 62 mm. in length. The feet are nearly entire, and are proportionally more slender than the known remains of the other species would indicate. The third metatarsal is 235 mm. in length, and 77 mm. in transverse diameter at its distal end. This species, which may be called Hadrosaurus agilis, will be fully described in this Journal at an early day.
Yale
YALE
RapidMiner, formerly YALE , is an environment for machine learning, data mining, text mining, predictive analytics, and business analytics. It is used for research, education, training, rapid prototyping, application development, and industrial applications...
College, New Haven, March 19, 1872.
In 1892, Marsh named a second species, C. annectens. This species later was reassigned to Anatosaurus and then Edmontosaurus
Edmontosaurus
Edmontosaurus is a genus of crestless hadrosaurid dinosaur. It contains two species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago,...
, where it is currently. G. R. Wieland named third species C. affinis in 1903, which he compared to C. annectens. C. affinis was founded on remains from the Pierre Shale
Pierre Shale
The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from North Dakota to New Mexico....
of South Dakota
South Dakota
South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...
, found in association with remains of the giant sea turtle Archelon
Archelon
Archelon is a genus of extinct sea turtle, the largest that has ever been documented.-Discovery:...
. At some point after its description, the fragmentary remains were mixed up with the original remains of C. agilis, and a toe bone from C. agilis was accidentally thought to be the only part of 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...
remains that could be located. This was corrected by Joseph Gregory in 1948, who found three toe bones from the right foot of a large hadrosaur in the Yale collections that had comparable preservation to the Pierre Shale turtle remains and were associated with labels in Wieland's handwriting. Gregory found the toe bones to be very similar in size to the corresponding bones of Marsh's Claosaurus annectens, but did not reassign the species due to its much older age and fragmentary remains. "C. affinis" was considered a dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
hadrosaur in the 2004 review by Jack Horner and colleagues. They reported its type material as lost, although they also reported these remains as only including a single toe bone, instead of the three toe bones of Gregory.
Reports of gastrolith
Gastrolith
A gastrolith, also called a stomach stone or gizzard stones, is a rock held inside a gastrointestinal tract. Gastroliths are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. The grain size depends upon the size of the animal and the gastrolith's...
s, or stomach stones, in Claosaurus are actually based on a probable double misidentification. First, the specimen is actually of Edmontosaurus annectens
Edmontosaurus
Edmontosaurus is a genus of crestless hadrosaurid dinosaur. It contains two species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago,...
. Barnum Brown
Barnum Brown
Barnum Brown , a paleontologist born in Carbondale, Kansas, and named after the circus showman P.T. Barnum, discovered the second fossil of Tyrannosaurus rex during a career that made him one of the most famous fossil hunters working from the late Victorian era into the early 20th century.Sponsored...
, who discovered the specimen in 1900, referred to it as Claosaurus, because E. annectens was thought to be a species of Claosaurus at the time. Additionally, it is more likely that the supposed gastroliths represent gravel washed in during burial.