Cedarosaurus
Encyclopedia
Cedarosaurus was a nasal-crested macronaria
n dinosaur
genus
from the Early Cretaceous
Period (Barremian
). It was a sauropod which lived in what is now Utah
. It was first described by Tidwell, Carpenter and Brooks in 1999.
It shows similarities to the brachiosaurid Eucamerotus
from the Wessex Formation
of southern England, as well as to Brachiosaurus
from the Morrison Formation
.
and radius than its relative Venenosaurus
. The ratio of the radius' least circumference to its length is .31 in Cedarosaurus. Metatarsal II is more gracile in Cedarosaurus.
Its middle tail vertebrae's neural spines angled anteriorly when the vertebrae are aligned. These vertebrae resemble those of Gondwanatitan
, Venenosaurus
, and Aeolosaurus
.
The Cedarosaurus relativeVenenosaurus had unusual lateral fossae, which looked like deep depressions in the outside walls of the vertebral centra. Some fossae are divided into two chambers by a ridge inside the depression. In most sauropods the fossae would form pneumatic openings leading to the interior of the centrum, rather than just being a depression. Less well-developed, but similar fossae are known from Cedarosaurus itself.
, Kim Manley, and Kenneth Carpenter
published a study on 115 clasts discovered in association with a Cedarosaurus specimen. These clasts were the first discovery of in situ gastroliths from the Cedar Mountain Formation
. The clasts were "partially matrix supported" and there were many contacts between clasts and bones and between the clasts themselves. The clasts were identified as gastroliths on the basis of their tight spatial distribution, partial matrix support and an edge-on orientation indicative of their being deposited while the carcass still had soft tissue. Their high surface reflectance values are consistent with other known dinosaur gastroliths. The clasts were generally of dull coloration, suggesting that color was not a major factor for the sauropod's decision making. All but three of the Cedarosaurus gastroliths were found within a .06 m volume of space. This space was located within the gut area. No other clasts were found within the quarry, which at the time had a volume of about 11 m cubed. The set of gastroliths is believed complete due to their being discovered in a single pocket deep in the quarry. The skeletal position suggests that the skeleton came to rest on its belly.
The total mass of the gastroliths was 7 kilograms, total volume 2703 ccs and the total surface area 4410 cm2. A majority, 67 of the 115 gastroliths, were less than 10 cc in volume. Individual clasts ranges from .04 cc to 270 cc in volume. The least massive clast was .1 gram and the most was 715 grams. Most of the gastroliths tended to be small. The clasts tended to be close to spherical in shape, with the largest specimens being the most irregular. 43% were oblate spheroids, 34% spheroids, 16% prolate spheroid
s, and 7% ellipsoidal. The largest gastroliths contributed the most to the total surface area of the set. Since some of the most irregular gastroliths are also the largest, it is unlikely that they were ingested by accident. Cedarosaurus may have found irregular clasts to be attractive potential gastroliths or was not selective about shape. Some gastroliths were so large an irregularly shaped that they may have been difficult to swallow. The gastroliths includes chert
, sandstone
, siltstone
, and quartzite
clasts. Some of the chert clasts actually contained fossils. The sandstone clasts tended to be fragile and some broke in the process of collection. 62% were chert, 31 percent were sandstone and siltstone, 7% were quartzite.
None of the gastroliths had the "soapy" texture popularly used to distinguish gastroliths from other types of clast. The researchers dismissed using a soapy texture to identify gastroliths as "unreliable." Gastroliths tended to be universally dull, although the colors represented were varied including black, dark brown, purplish red and grey-blue. Reflectance values greater than 50% are very diagnostic for identifying gastroliths. Clasts from beaches and streams tended to have reflectance values of less than 35%. Less than ten percent of beach clasts have reflectance values lying between 50 and 80%. The most reflective gastroliths were composed of chert. Some of the gastroliths couldn't be tested for reflectance due to a confounding metallic coating, which may have been hematite
. Expansion and contraction of the supporting mudstone around the inflexible clasts actually left series of parallel scratches in the coating. The metallic coating "probably originated from the iron
rich mudstone
" surround the fossils. The sandstone gastroliths may have been rendered fragile after deposition by loss of cement
caused by the external chemical environment. If the clasts had been that fragile while the animal was alive, they probably rolled and tumbled in the digestive tract. If they were more robust, they could have served as part of a ball-mill system. The high surface area to volume ratio of the largest clasts "also supports a grinding or crushing model."
Macronaria
Macronaria is a clade of sauropod dinosaurs from the Middle Jurassic to Late Cretaceous Periods of what are now North America, South America, Europe, Asia and Africa. The name means 'large nostrils' , in reference to the large nasal openings high on the head that probably supported fleshy...
n 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...
genus
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...
from the Early 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 (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...
). It was a sauropod which lived in what is now 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 was first described by Tidwell, Carpenter and Brooks in 1999.
It shows similarities to the brachiosaurid Eucamerotus
Eucamerotus
Eucamerotus was a genus of sauropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England. It is known from vertebral remains, and a partial skeleton has been referred, although this has not been accepted...
from the Wessex Formation
Wessex Formation
The Wessex Formation is an English fossil site and geological formation that dates to the Barremian stage of the Early Cretaceous. It is part of the Wealden Group and underlies the younger Vectis Formation.-Invertebrates:...
of southern England, as well as to Brachiosaurus
Brachiosaurus
Brachiosaurus is a genus of sauropod dinosaur from the Jurassic Morrison Formation of North America. It was first described by Elmer S. Riggs in 1903 from fossils found in the Grand River Canyon of western Colorado, in the United States. Riggs named the dinosaur Brachiosaurus altithorax,...
from the Morrison Formation
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...
.
Anatomy
Cedarosaurus had a more gracile ulnaUlna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
and radius than its relative Venenosaurus
Venenosaurus
Venenosaurus named after the Poison Strip Member of the Cedar Mountain Formation in Utah, where the fossils were discovered by a Denver Museum of Natural History volunteer Tony DiCroce in 1998. Venenosaurus dicrocei was first described as a new species in 2001 by Virginia Tidwell, Kenneth...
. The ratio of the radius' least circumference to its length is .31 in Cedarosaurus. Metatarsal II is more gracile in Cedarosaurus.
Its middle tail vertebrae's neural spines angled anteriorly when the vertebrae are aligned. These vertebrae resemble those of Gondwanatitan
Gondwanatitan
Gondwanatitan was a titanosaurian sauropod dinosaur. Gondwanatitan was found in Brazil, at the time part of the southern supercontinent Gondwana , in the late Cretaceous Period . Like some other sauropods, Gondwanatitan was tall and ate tough shoots and leaves off of the tops of trees. G...
, Venenosaurus
Venenosaurus
Venenosaurus named after the Poison Strip Member of the Cedar Mountain Formation in Utah, where the fossils were discovered by a Denver Museum of Natural History volunteer Tony DiCroce in 1998. Venenosaurus dicrocei was first described as a new species in 2001 by Virginia Tidwell, Kenneth...
, and 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...
.
The Cedarosaurus relativeVenenosaurus had unusual lateral fossae, which looked like deep depressions in the outside walls of the vertebral centra. Some fossae are divided into two chambers by a ridge inside the depression. In most sauropods the fossae would form pneumatic openings leading to the interior of the centrum, rather than just being a depression. Less well-developed, but similar fossae are known from Cedarosaurus itself.
Gastroliths
In 2001 Frank SandersFrank Sanders
Frank Vondel Sanders , is a former professional American football player who was selected by the Arizona Cardinals in the second round of the 1995 NFL Draft. A 6'1", 207-lb. wide receiver from Auburn University, Sanders played in nine NFL seasons from 1995 to 2003...
, Kim Manley, and Kenneth Carpenter
Kenneth Carpenter
Kenneth Carpenter is a paleontologist. He is the museum director of the USU Eastern Prehistoric Museum and author or co-author of a number of books on dinosaurs and Mesozoic life...
published a study on 115 clasts discovered in association with a Cedarosaurus specimen. These clasts were the first discovery of in situ gastroliths from the Cedar Mountain Formation
Cedar Mountain Formation
The Cedar Mountain Formation is the name given to distinctive sedimentary rocks in eastern Utah that occur between the underlying Morrison Formation and overlying Naturita Formation . It is composed of non-marine sediments, that is, sediments deposited in rivers, lakes and on flood plains...
. The clasts were "partially matrix supported" and there were many contacts between clasts and bones and between the clasts themselves. The clasts were identified as gastroliths on the basis of their tight spatial distribution, partial matrix support and an edge-on orientation indicative of their being deposited while the carcass still had soft tissue. Their high surface reflectance values are consistent with other known dinosaur gastroliths. The clasts were generally of dull coloration, suggesting that color was not a major factor for the sauropod's decision making. All but three of the Cedarosaurus gastroliths were found within a .06 m volume of space. This space was located within the gut area. No other clasts were found within the quarry, which at the time had a volume of about 11 m cubed. The set of gastroliths is believed complete due to their being discovered in a single pocket deep in the quarry. The skeletal position suggests that the skeleton came to rest on its belly.
The total mass of the gastroliths was 7 kilograms, total volume 2703 ccs and the total surface area 4410 cm2. A majority, 67 of the 115 gastroliths, were less than 10 cc in volume. Individual clasts ranges from .04 cc to 270 cc in volume. The least massive clast was .1 gram and the most was 715 grams. Most of the gastroliths tended to be small. The clasts tended to be close to spherical in shape, with the largest specimens being the most irregular. 43% were oblate spheroids, 34% spheroids, 16% prolate spheroid
Prolate spheroid
A prolate spheroid is a spheroid in which the polar axis is greater than the equatorial diameter. Prolate spheroids stand in contrast to oblate spheroids...
s, and 7% ellipsoidal. The largest gastroliths contributed the most to the total surface area of the set. Since some of the most irregular gastroliths are also the largest, it is unlikely that they were ingested by accident. Cedarosaurus may have found irregular clasts to be attractive potential gastroliths or was not selective about shape. Some gastroliths were so large an irregularly shaped that they may have been difficult to swallow. The gastroliths includes chert
Chert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
, 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,...
, siltstone
Siltstone
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...
, and quartzite
Quartzite
Quartzite is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink...
clasts. Some of the chert clasts actually contained fossils. The sandstone clasts tended to be fragile and some broke in the process of collection. 62% were chert, 31 percent were sandstone and siltstone, 7% were quartzite.
None of the gastroliths had the "soapy" texture popularly used to distinguish gastroliths from other types of clast. The researchers dismissed using a soapy texture to identify gastroliths as "unreliable." Gastroliths tended to be universally dull, although the colors represented were varied including black, dark brown, purplish red and grey-blue. Reflectance values greater than 50% are very diagnostic for identifying gastroliths. Clasts from beaches and streams tended to have reflectance values of less than 35%. Less than ten percent of beach clasts have reflectance values lying between 50 and 80%. The most reflective gastroliths were composed of chert. Some of the gastroliths couldn't be tested for reflectance due to a confounding metallic coating, which may have been hematite
Hematite
Hematite, also spelled as haematite, is the mineral form of iron oxide , one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum...
. Expansion and contraction of the supporting mudstone around the inflexible clasts actually left series of parallel scratches in the coating. The metallic coating "probably originated from the iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
rich 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...
" surround the fossils. The sandstone gastroliths may have been rendered fragile after deposition by loss of cement
Cement
In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...
caused by the external chemical environment. If the clasts had been that fragile while the animal was alive, they probably rolled and tumbled in the digestive tract. If they were more robust, they could have served as part of a ball-mill system. The high surface area to volume ratio of the largest clasts "also supports a grinding or crushing model."