Cotylorhynchus
Encyclopedia
Cotylorhynchus was a very large mammal-like reptile (more accurately synapsid) that lived in the southern part of what is now North America
during the Early Permian
period and persisted until the late-Mid Permian (about 265 mya). Cotylorhynchus are the most well known of the synapsid clade Caseidae
and are in the order Pelycosauria.
The Cotylorhynchus were the largest pelycosaurs, the largest terrestrial vertebrates of their time, as well as the terrestrial vertebrates up to that time. They were herbivores, and because of their enormous size they probably did not fear any of the carnivores.
Cotylorhynchus was a massively built animal with a disproportionately small head and a huge barrel-shaped body. They could grow to lengths of up to 20 feet and could achieve weights of up to 2 tons. Their skeletal features included a massive scapulocoracoid
, humeri with large flared ends, stout forearm bones and broad, robust hands that had large claws. Certain features of their hands indicate that they had to dig
considerably to obtain their food supply and also they may have used these features to dig burrows
for shelter or safety. Their digits were believed to have a considerable range of motion and large retractor processes on the ventral surfaces of the unguals allowed them to flex their claws with powerful motions. Also, the articulatory surfaces of their phalanges were oblique to the bone's long axis rather than perpendicular to it. This allowed for much more surface area for the flexor muscles.
Their skulls are distinctive in the presence of large temporal openings
and very large nostril openings, which could have been utilized for better breathing
or may have housed some sort of sensory
or moisture conserving organ. Also they featured large pineal openings and a snout or upper jaw that overhangs the row of teeth to form a projecting rostrum
. Rounded deep pits and possibly large depressions were present on the outer surface of the skull. Their teeth were very similar to those of iguanas with posterior marginal teeth that bore a longitudinal row of cusps.
Cotylorhynchus were considered a part of the first wave of amniote
diversity. There have been three species of Cotylorhynchus discovered: C. hancocki, C. romeri and C. bransoni. C. hancocki is believed to be a descendent of the slightly smaller C. romeri. Various skeletal parts of C. romeri have been found around central Oklahoma
in parts of Cleveland County
. Parts of C. hancocki have been found in northern Texas
in Hardeman
and Knox
counties. C. bransoni specimens have been uncovered in Kingfisher
and Blaine
Counties of central-northwest Oklahoma.
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...
during the Early Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
period and persisted until the late-Mid Permian (about 265 mya). Cotylorhynchus are the most well known of the synapsid clade Caseidae
Caseidae
The Caseidae were a widespread group of very primitive herbivorous synapsids, which appeared during the later early Permian and persisted until the late middle Permian. Although ranging in size from 1 to 5½ meters in body length, caseids were surprisingly conservative in their skeletal anatomy and...
and are in the order Pelycosauria.
The Cotylorhynchus were the largest pelycosaurs, the largest terrestrial vertebrates of their time, as well as the terrestrial vertebrates up to that time. They were herbivores, and because of their enormous size they probably did not fear any of the carnivores.
Description
Scapulocoracoid
The Scapulocoracoid is the unit of the pectoral girdle that contains the coracoid and scapula.The coracoid itself is a beak-shaped bone that is commonly found in most vertebrates with a few exceptions.The scapula is commonly known as the shoulder blade...
, humeri with large flared ends, stout forearm bones and broad, robust hands that had large claws. Certain features of their hands indicate that they had to dig
Dig
-Music:* Dig , an American rock bandAlbums* Dig , or the title song* Dig * Dig * Dig , or the title song* Dig...
considerably to obtain their food supply and also they may have used these features to dig burrows
Burrows
Burrows is a provincial electoral division in the Canadian province of Manitoba. It was created by redistribution in 1957, and formally came into existence in the provincial election of 1958. The riding is located in the northern part of Winnipeg....
for shelter or safety. Their digits were believed to have a considerable range of motion and large retractor processes on the ventral surfaces of the unguals allowed them to flex their claws with powerful motions. Also, the articulatory surfaces of their phalanges were oblique to the bone's long axis rather than perpendicular to it. This allowed for much more surface area for the flexor muscles.
Their skulls are distinctive in the presence of large temporal openings
Temple (anatomy)
Temple indicates the side of the head behind the eyes. The bone beneath is the temporal bone as well as part of the sphenoid bone.-Anatomy:Cladists classify land vertebrates based on the presence of an upper hole, a lower hole, both, or neither in the cover of dermal bone which formerly covered the...
and very large nostril openings, which could have been utilized for better breathing
Breathing
Breathing is the process that moves air in and out of the lungs. Aerobic organisms require oxygen to release energy via respiration, in the form of the metabolism of energy-rich molecules such as glucose. Breathing is only one process that delivers oxygen to where it is needed in the body and...
or may have housed some sort of sensory
Sensory
Sensory may refer to:relating to senses or smellIn biology:* Sensory preference* Sensory system, part of the nervous system of organisms* Sensory neuron, nerve cell responsible for transmitting information about external stimuli...
or moisture conserving organ. Also they featured large pineal openings and a snout or upper jaw that overhangs the row of teeth to form a projecting rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
. Rounded deep pits and possibly large depressions were present on the outer surface of the skull. Their teeth were very similar to those of iguanas with posterior marginal teeth that bore a longitudinal row of cusps.
Discovery
Amniote
The amniotes are a group of tetrapods that have a terrestrially adapted egg. They include synapsids and sauropsids , as well as their fossil ancestors. Amniote embryos, whether laid as eggs or carried by the female, are protected and aided by several extensive membranes...
diversity. There have been three species of Cotylorhynchus discovered: C. hancocki, C. romeri and C. bransoni. C. hancocki is believed to be a descendent of the slightly smaller C. romeri. Various skeletal parts of C. romeri have been found around central Oklahoma
Oklahoma
Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...
in parts of Cleveland County
Cleveland County, Oklahoma
Cleveland County is a county in the central part of the U.S. state of Oklahoma. The population was 255,755 at the 2010 census. Its county seat is Norman. Cleveland County is part of the Oklahoma City Metropolitan Statistical Area.-History:...
. Parts of C. hancocki have been found in northern Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
in Hardeman
Hardeman County, Texas
As of the census of 2000, there were 4,724 people, 1,943 households, and 1,319 families residing in the county. The population density was 7 people per square mile . There were 2,358 housing units at an average density of 3 per square mile...
and Knox
Knox County, Texas
As of the census of 2000, there were 4,253 people, 1,690 households, and 1,166 families residing in the county. The population density was 5 people per square mile . There were 2,129 housing units at an average density of 2 per square mile...
counties. C. bransoni specimens have been uncovered in Kingfisher
Kingfisher County, Oklahoma
Kingfisher County is a county located in the U.S. state of Oklahoma. As of 2000, the population was 14,384. Its county seat is Kingfisher.-History:...
and Blaine
Blaine County, Oklahoma
Blaine County is a county located in the U.S. state of Oklahoma. As of 2000, the population is 11,976. Its county seat is Watonga. Blaine County is the birthplace of voice actor Clarence Nash, the voice of Donald Duck....
Counties of central-northwest Oklahoma.