Peloroplites
Encyclopedia
Peloroplites is a genus
of nodosaurid
armored
dinosaur
from Lower Cretaceous rocks of Utah
. It is known from a partial skull and partial postcrania
l remains from the base of the Mussentuchit Member of the Cedar Mountain Formation
, deposited during the Aptian
-Albian
boundary, about 116 to 109 million years ago, and was found in Emery County, Utah
. It was named in 2008 by Kenneth Carpenter
and colleagues.
Peloroplites was about 5 to 5.5 meters (16 to 18 ft) long, comparable to its approximate contemporary Sauropelta
. It is one of the largest known nodosaurids, and came from a time when ankylosauria
ns in general were attaining large sizes.
CEUM
26331, a partial skull, with numerous postcranial bones recovered from the same quarry. These specimens were designated paratype
s. The type species
is P. cedrimontanus, in reference to the Cedar Mountain Formation.
The skull was about 56 centimeters (22 in) long, and 35.5 centimeters (14 in) wide between the eyes. It lacked beak
teeth, and had only modest horn-like projections. The top of the skull was only slightly domed, and the only preserved upper cheek
tooth was large and similar to teeth assigned to Priconodon
, another large nodosaurid from about the same time. The lower jaws are represented by their rear halves, and were heavily built.
Of the postcrania
l skeleton, bones from all areas of the body are represented, except the hind foot. Six fused vertebrae supported the hip
, as in Silvisaurus
. The ilia
, the largest bones of the hip, appear to have been flared out unusually, at 55° compared to the ~30° or ~40° degrees of other nodosaurids, but this could be a preservational accident. Unlike most other nodosaurids, the ulna
was long and straight, and the major ankle bone (the astragalus
) was not fused to the shin
.
, in a quarry that also produced fossil
s of a turtle
, a pterosaur
, four individuals of a new brachiosaurid
sauropod, the basal
ankylosaurid
Cedarpelta
, and an iguanodont
ornithopod
. Ankylosaurians attained large sizes at the Aptian
-Albian
boundary; both Peloroplites and Cedarpelta are comparable in size to Sauropelta, a nodosaurid from about the same time but known from the Cloverly Formation
of Wyoming
and Montana
. In fact, isolated bones from older levels of the Cedar Mountain Formation, assigned to Sauropelta, may actually pertain to Peloroplites.
Ankylosaurians are usually interpreted as low-browsing quadruped
al herbivore
s. The large teeth and robust jaws of Peloroplites suggest that it was consuming tougher forage than other ankylosaurians.
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 nodosaurid
Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:...
armored
Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...
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 Lower Cretaceous rocks 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 known from a partial skull and partial postcrania
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...
l remains from the base of the Mussentuchit Member of 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...
, deposited during the 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...
-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...
boundary, about 116 to 109 million years ago, and was found in Emery County, Utah
Emery County, Utah
Emery County is a county located in the U.S. state of Utah. As of 2000 the population was 10,860, and by 2009 had been estimated to decrease to 10,629. It was named for George W. Emery, governor of the Utah Territory in 1875...
. It was named in 2008 by 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...
and colleagues.
Peloroplites was about 5 to 5.5 meters (16 to 18 ft) long, comparable to its approximate contemporary Sauropelta
Sauropelta
Sauropelta is a genus of nodosaurid dinosaur that existed in the Early Cretaceous Period of North America. One species has been named although others may have existed. Anatomically, Sauropelta is one of the most well-understood nodosaurids, with fossilized remains recovered in the U.S. states of...
. It is one of the largest known nodosaurids, and came from a time when ankylosauria
Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...
ns in general were attaining large sizes.
Description
Peloroplites 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...
CEUM
College of Eastern Utah Prehistoric Museum
The USU Eastern Prehistoric Museum, formerly known as the College of Eastern Utah Prehistoric Museum, is a museum accredited by the American Association of Museums located in Price, Utah. The museum seeks to promote public understanding of prehistory through interpretive exhibits, educational...
26331, a partial skull, with numerous postcranial bones recovered from the same quarry. These specimens were designated paratype
Paratype
Paratype is a technical term used in the scientific naming of species and other taxa of organisms. The exact meaning of the term paratype when it is used in zoology is not the same as the meaning when it is used in botany...
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 P. cedrimontanus, in reference to the Cedar Mountain Formation.
The skull was about 56 centimeters (22 in) long, and 35.5 centimeters (14 in) wide between the eyes. It lacked beak
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
teeth, and had only modest horn-like projections. The top of the skull was only slightly domed, and the only preserved upper cheek
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
tooth was large and similar to teeth assigned to Priconodon
Priconodon
Priconodon is an extinct genus of dinosaur , known from its large teeth. Its remains have been found in the Aptian-Albian age Lower Cretaceous Arundel Formation of Muirkirk, Prince George's County, Maryland.-History:...
, another large nodosaurid from about the same time. The lower jaws are represented by their rear halves, and were heavily built.
Of the postcrania
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...
l skeleton, bones from all areas of the body are represented, except the hind foot. Six fused vertebrae supported the hip
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:...
, as in Silvisaurus
Silvisaurus
Silvisaurus, from the Latin silva "woodland" and Greek saurus "lizard", is a nodosaurid ankylosaur from the middle Cretaceous of Kansas.-Discovery and species:...
. The ilia
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 ,...
, the largest bones of the hip, appear to have been flared out unusually, at 55° compared to the ~30° or ~40° degrees of other nodosaurids, but this could be a preservational accident. Unlike most other nodosaurids, the ulna
Ulna
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...
was long and straight, and the major ankle bone (the astragalus
Talus bone
-External links:* *...
) was not fused to the shin
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....
.
Paleobiology and paleoecology
Peloroplites was found in mudstoneMudstone
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...
, in a quarry that also produced fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s of a turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
, a pterosaur
Pterosaur
Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...
, four individuals of a new brachiosaurid
Brachiosauridae
Brachiosauridae are a family of dinosaurs, whose members are known as brachiosaurids. They were herbivorous quadrupeds with longer forelegs than hind legs - the name derives from the Greek for arm lizard - and long necks...
sauropod, the basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
ankylosaurid
Ankylosauridae
An ankylosaurid is a member of the Ankylosauridae family of armored dinosaurs that evolved 125 million years ago and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event...
Cedarpelta
Cedarpelta
Cedarpelta is an extinct genus of basal ankylosaurid ankylosaur, based on material recovered from the Lower Cretaceous of North America. The skull lacks extensive cranial ornamentation, a trait which has been interpreted as plesiomorphic for ankylosaurs....
, and an iguanodont
Iguanodont
Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodonts were one of the first groups of dinosaurs to be found...
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...
. Ankylosaurians attained large sizes at the 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...
-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...
boundary; both Peloroplites and Cedarpelta are comparable in size to Sauropelta, a nodosaurid from about the same time but known from the Cloverly Formation
Cloverly Formation
The Cloverly Formation are Lower Cretaceous strata located in Montana and Wyoming, in the western United States. The term now includes strata that had formerly been called the Dakota Formation in central and southern Wyoming.-Members:...
of Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
and Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
. In fact, isolated bones from older levels of the Cedar Mountain Formation, assigned to Sauropelta, may actually pertain to Peloroplites.
Ankylosaurians are usually interpreted as low-browsing quadruped
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"...
al 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...
s. The large teeth and robust jaws of Peloroplites suggest that it was consuming tougher forage than other ankylosaurians.
