Priconodon
Encyclopedia
Priconodon is an extinct genus
of dinosaur
(perhaps nodosaurid), 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
.
. As ankylosauria
ns were by and large unknown at the time, he compared it to Diracodon (=Stegosaurus
) teeth. It wasn't identified as an ankylosaurian until Walter Coombs assigned it to Nodosauridae
in 1978.
As a tooth genus, it has not attracted much attention. Recently, though, Ken Carpenter
and James Kirkland (1998), in a review of North America
n Lower Cretaceous ankylosaurs, considered it tentatively valid as an unusually large nodosaurid, larger than all those described before. Carpenter (2001) retained it as a valid nodosaurid, but did not employ it in his phylogenetic analysis
. Vickaryous et al. (2004), in a review of armored dinosaurs, considered it to be dubious
without comment. West and Tibert, however, followed this with a preliminary account of a morphometric study that found it to be a unique genus.
tooth, and tentatively added a robust tibia
(USNM 9154) to the genus. They found the lack of armor
found in the Arundel to be peculiar, but noted that fossils are rare in that formation anyway.
al herbivore
. It would have been a large nodosaurid, but since only teeth are definitely known for the genus, size estimation has not been done.
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 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...
(perhaps nodosaurid), known from its large teeth. Its remains have been found in 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...
age Lower Cretaceous Arundel Formation
Arundel Formation
The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland of the United States of America. It is of Aptian age . This rock unit had been economically important as a source of iron ore, but is now more notable for...
of Muirkirk
Muirkirk, Maryland
Muirkirk is an unincorporated area in northern Prince George's County, Maryland, United States, located between Baltimore and Washington, D.C. in the central part of the state.It is located along U.S. 1 between Beltsville and Laurel...
, Prince George's County, Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
.
History
O. C. Marsh named the genus for USNM 2135, a large worn tooth from what was then called the Potomac FormationPotomac Formation
The Potomac Formation consists of Lower Cretaceous to Upper Cretaceous strata located in Delaware, Maryland, and New Jersey, in the eastern United States.Flora found include large cycads....
. As 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 were by and large unknown at the time, he compared it to Diracodon (=Stegosaurus
Stegosaurus
Stegosaurus is a genus of armored stegosaurid dinosaur. They lived during the Late Jurassic period , some 155 to 150 million years ago in what is now western North America. In 2006, a specimen of Stegosaurus was announced from Portugal, showing that they were present in Europe as well...
) teeth. It wasn't identified as an ankylosaurian until Walter Coombs assigned it to 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:...
in 1978.
As a tooth genus, it has not attracted much attention. Recently, though, Ken Carpenter
Ken Carpenter
William Kenneth Carpenter was the USC's first two-time NCAA champion in a weight event. In 1936, Carpenter captured the gold medal in the discus throw at the 1936 Summer Olympics with a toss of 50.48 meters...
and James Kirkland (1998), in a review 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...
n Lower Cretaceous ankylosaurs, considered it tentatively valid as an unusually large nodosaurid, larger than all those described before. Carpenter (2001) retained it as a valid nodosaurid, but did not employ it in his phylogenetic analysis
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
. Vickaryous et al. (2004), in a review of armored dinosaurs, considered it to be dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
without comment. West and Tibert, however, followed this with a preliminary account of a morphometric study that found it to be a unique genus.
Material
Carpenter and Kirkland (1998) listed 12 additional teeth from the same area as the holotypeHolotype
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...
tooth, and tentatively added a robust tibia
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....
(USNM 9154) to the genus. They found the lack of armor
Armour (zoology)
Armour in animals is external or superficial protection against attack by predators, formed as part of the body , usually through the hardening of body tissues, outgrowths or secretions. It has therefore mostly developed in 'prey' species...
found in the Arundel to be peculiar, but noted that fossils are rare in that formation anyway.
Paleobiology
As a nodosaurid, Priconodon would have been a slow, armored, quadrupedQuadruped
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...
. It would have been a large nodosaurid, but since only teeth are definitely known for the genus, size estimation has not been done.