Cedarpelta
Encyclopedia
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.
The scientific name means "Bilbey and Hall's Cedar (Mountain) shield," with the genus
named for the Cedar Mountain Formation and the animal's armored plates and the species
named for Sue Ann Bilbey and Evan Hall, discoverers of the type locality
.
Cedarpelta is known from remains recovered at the CEM and Price River II quarries (PR-2) in eastern Utah; these sites were originally thought to be within the Ruby Ranch Member of the Cedar Mountain Formation, but are now assigned to the base of the overlying Mussentuchit Member, dating to between 116 and 109 million years old (approximately the Aptian
-Albian
boundary).
with a caudolaterally oriented, trochlear-like process, a premaxilla
with six conical teeth, and a straight ischium. The presence of premaxillary teeth is a plesiomorphic character because it is present in other, primitive ornithischians. In contrast, closure of the opening on the side of the skull behind the orbit, the lateral temporal fenestra, is an advanced (apomorphic) character only known in ankylosaurid ankylosaurs.
Two skulls are known, and the skull
length for Cedarpelta is estimated to have been roughly 60 centimetres (23.6 in). Significantly, one of the Cedarpelta skulls was found disarticulated, a first for an ankylosaur skull, allowing paleontologists a unique opportunity to examine the individual bones instead of being limited to an ossified unit.
and Shamosaurus
scutatus of Mongolia
, and they placed the taxon
within the Family Ankylosauridae. Vickaryous et al. (2004), however, interpreted the genus as the basalmost member of the Family Nodosauridae
, most closely related to the nodosaurids Pawpawsaurus campbelli, Silvisaurus condrayi, and Sauropelta
edwardsorum. However, new material of the skeleton confirms the original identification of Carpenter et al. of Cedarpelta being one of the most primitive ankylosaurids.
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 basal ankylosaurid ankylosaur, based on material recovered from the Lower 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...
of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. The skull lacks extensive cranial ornamentation, a trait which has been interpreted as plesiomorphic for ankylosaurs.
The scientific name means "Bilbey and Hall's Cedar (Mountain) shield," with the 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...
named for the Cedar Mountain Formation and the animal's armored plates and the species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
named for Sue Ann Bilbey and Evan Hall, discoverers of the type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
.
Cedarpelta is known from remains recovered at the CEM and Price River II quarries (PR-2) in eastern Utah; these sites were originally thought to be within the Ruby Ranch Member of the Cedar Mountain Formation, but are now assigned to the base of the overlying Mussentuchit Member, dating to between 116 and 109 million years old (approximately 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).
Description
Carpenter et al. (2001) diagnose Cedarpelta by the presence of a rostrocaudally elongate pterygoidPterygoid
Pterygoid can refer to:* Pterygoid processes of the sphenoid bone** The Lateral pterygoid plate by it* a muscle such as Lateral pterygoid muscle or Medial pterygoid muscle* a branch of the Mandibular nerve...
with a caudolaterally oriented, trochlear-like process, a premaxilla
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....
with six conical teeth, and a straight ischium. The presence of premaxillary teeth is a plesiomorphic character because it is present in other, primitive ornithischians. In contrast, closure of the opening on the side of the skull behind the orbit, the lateral temporal fenestra, is an advanced (apomorphic) character only known in ankylosaurid ankylosaurs.
Two skulls are known, and the skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
length for Cedarpelta is estimated to have been roughly 60 centimetres (23.6 in). Significantly, one of the Cedarpelta skulls was found disarticulated, a first for an ankylosaur skull, allowing paleontologists a unique opportunity to examine the individual bones instead of being limited to an ossified unit.
Holotype
Carpenter et al. (2001) designated CEUM 12360 as the holotype specimen of Cedarpelta bilbeyhallorum (CEUM is the acronym of the College of Eastern Utah Prehistoric Museum in Price, Utah). CEUM 12360 consists of an articulated, incomplete skull lacking the snout and mandibles. Carpenter et al. (2001) also designated a long list of paratype material, mostly isolated bones that could be referred to Cedarpelta bilbeyhallorum.Phylogenetics
Cedarpelta bilbeyhallorum was believed by Carpenter et al. (2001) to be closely related to Gobisaurus domoculus of north-central ChinaChina
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
and Shamosaurus
Shamosaurus
Shamosaurus is an extinct genus of basal ankylosaurid ankylosaur from Early Cretaceous deposits of Höövör, Mongolia. Shamosaurus is known from the holotype PIN N 3779/2 complete skull and jaw and the paratypes include partial skeleton remains and an armor. It was collected from the...
scutatus of Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
, and they placed the taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
within the Family Ankylosauridae. Vickaryous et al. (2004), however, interpreted the genus as the basalmost member of the Family Nodosauridae
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:...
, most closely related to the nodosaurids Pawpawsaurus campbelli, Silvisaurus condrayi, and 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...
edwardsorum. However, new material of the skeleton confirms the original identification of Carpenter et al. of Cedarpelta being one of the most primitive ankylosaurids.