Gargoyleosaurus
Encyclopedia
Gargoyleosaurus is one of the earliest ankylosaurs known from reasonably complete fossil remains. Its skull measures 29 centimetres (11.4 in) in length, and its total body length is an estimated 3 to 4 m (9.8 to 13.1 ft). It may have weighed as much as 1 tonnes (2,204.6 lb). The holotype
was discovered at the Bone Cabin Quarry West locality, in Albany County, Wyoming
in exposures
of the Upper Jurassic
(Kimmeridgian
to Tithonian
stages
) Morrison Formation
.
The type species
, G. parkpinorum (originally G. parkpini) was described by Ken Carpenter
et al. in 1998. A mounted skeletal reconstruction of Gargoyleosaurus parkpinorum can be seen at the Denver Museum of Nature and Science
. Gargoyleosaurus was present in stratigraphic zone 2 of the Morrison Formation.
The holotype specimen of Gargoyleosaurus parkpinorum was collected by Western Paleontology Labs in 1996 and is currently held in the collections of the Denver Museum of Nature and Science
, Denver, Colorado
. Besides the holotype, two other partial skeletons are known (although not yet described). The holotype consists of most of the skull and a partial postcranial skeleton. The specimen was originally described as Gargoyleosaurus parkpini by Carpenter, Miles and Cloward in 1998, then renamed G. parkpinorum by Carpenter et al. in 2001, in accordance with ICZN
art. 31.1.2A.
and skeleton
has been recovered, and the taxon
displays cranial sculpturing, including pronounced deltoid
quadratojugal
and squamosal
bosses. The taxon is further characterized by a narrow rostrum (in dorsal view), the presence of seven conical teeth in each premaxilla
, an incomplete osseous nasal septum, a linerarly arranged nasal cavity, the absence of an osseus secondary palate
, and, as regards osteoderms, two sets of co-ossified cervical plates and a number of elongate conical spines.
Vickaryous et al. (2004) place Gargoyleosaurus parkpinorum within the Family Ankylosauridae
of the Ankylosauria
and are in agreement with most previous phylogenetic hypotheses, which place the genus
as the sister group to all other ankylosaurids (i.e., members of the Ankylosauridae). These studies however, only utilized the skull, whereas many of the distinctive features of the family Polacanthidae are in the postcranial skeleton.
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...
was discovered at the Bone Cabin Quarry West locality, in Albany County, 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...
in exposures
Geologic formation
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...
of the Upper Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
(Kimmeridgian
Kimmeridgian
In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma . The Kimmeridgian follows the Oxfordian and precedes the Tithonian....
to Tithonian
Tithonian
In the geologic timescale the Tithonian is the latest age of the Late Jurassic epoch or the uppermost stage of the Upper Jurassic series. It spans the time between 150.8 ± 4 Ma and 145.5 ± 4 Ma...
stages
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
) 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...
.
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...
, G. parkpinorum (originally G. parkpini) was described by Ken 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...
et al. in 1998. A mounted skeletal reconstruction of Gargoyleosaurus parkpinorum can be seen at the Denver Museum of Nature and Science
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...
. Gargoyleosaurus was present in stratigraphic zone 2 of the Morrison Formation.
Holotype
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...
, Denver, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
. Besides the holotype, two other partial skeletons are known (although not yet described). The holotype consists of most of the skull and a partial postcranial skeleton. The specimen was originally described as Gargoyleosaurus parkpini by Carpenter, Miles and Cloward in 1998, then renamed G. parkpinorum by Carpenter et al. in 2001, in accordance with ICZN
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
art. 31.1.2A.
Classification
Much of the skullSkull
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...
and skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
has been recovered, and 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...
displays cranial sculpturing, including pronounced deltoid
Deltoid
Deltoid can refer to:* The deltoid muscle, a muscle in the shoulder* Kite , also known as a deltoid, a type of quadrilateral* A deltoid curve, a three-sided hypocycloid* A leaf shape* The deltoid tuberosity, a part of the humerus...
quadratojugal
Quadratojugal
The quadratojugal is a small jaw bone that is present in most amphibians, reptiles, and birds, but has been lost in mammals. It is connected to the jugal as well as other bones, though these may vary with species....
and squamosal
Squamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
bosses. The taxon is further characterized by a narrow rostrum (in dorsal view), the presence of seven conical teeth in each 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....
, an incomplete osseous nasal septum, a linerarly arranged nasal cavity, the absence of an osseus secondary palate
Secondary palate
The secondary palate is an anatomical structure that divides the nasal cavity from the oral cavity in many vertebrates.In human embryology, it refers to that portion of the hard palate that is formed by the growth of the two palatine shelves medially and their mutual fusion in the midline...
, and, as regards osteoderms, two sets of co-ossified cervical plates and a number of elongate conical spines.
Vickaryous et al. (2004) place Gargoyleosaurus parkpinorum within the Family Ankylosauridae
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...
of the 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...
and are in agreement with most previous phylogenetic hypotheses, which place 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...
as the sister group to all other ankylosaurids (i.e., members of the Ankylosauridae). These studies however, only utilized the skull, whereas many of the distinctive features of the family Polacanthidae are in the postcranial skeleton.
External links
- Gargoyleosaurus from the Natural History Museum