Cteniogenys
Encyclopedia
Cteniogenys is a genus
of choristodere
, a morphologically
diverse group of aquatic reptiles. It had a wide distribution temporally and geographically, from the Middle Jurassic
and Late Jurassic
of western Europe
, to the Late Jurassic
-age Morrison Formation
of western North America
, to the Late Cretaceous
of Alberta
, Canada
. The genus was named in 1928 by Charles W. Gilmore
, from a lower jaw collected during the late 19th century by Othniel Charles Marsh
's workers at Como Bluff
. He tentatively described the genus as a lizard, noting that it could instead be a frog. New material from Europe permitted Susan Evans to reevalute it as an early choristodere in 1989. To date it is only known from fragmentary specimens. Morrison Formation Cteniogenys were 25 to 50 cm (9.8 to 19.7 in) long, and probably weighed less than 500 grams (1.1 lb). The skull of this genus was long and slender, and the jaws had numerous conical teeth. Cteniogenys in the Morrison probably fed on insects and small fish. It is mostly known from freshwater sites (rivers and ponds), and is a rare find in the formation (only 60 specimens out of over 2,800 total vertebrate specimens known from the formation), mostly known from northern outcrops (particularly Wyoming
). The Late Cretaceous record of this genus consists of a handful of skull and jaw fragments from the Oldman Formation
and Dinosaur Park Formation
. Given the long gap in time, these may represent a different, as-yet undetermined 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...
of choristodere
Choristodera
Choristodera is an order of semi-aquatic diapsid reptiles which ranged from the Middle Jurassic, or possibly Late Triassic, to at least the early Miocene. Choristoderes have been found in North America, Asia, and Europe. The most common fossils are typically found from the Late Cretaceous to the...
, a morphologically
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
diverse group of aquatic reptiles. It had a wide distribution temporally and geographically, from the Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
and Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
of western Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, to the Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
-age 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...
of western 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...
, to the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
of Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. The genus was named in 1928 by Charles W. Gilmore
Charles W. Gilmore
Charles Whitney Gilmore was an American paleontologist, who named dinosaurs in North America and Mongolia, including the Cretaceous sauropod Alamosaurus, Alectrosaurus, Archaeornithomimus, Bactrosaurus, Brachyceratops, Chirostenotes, Mongolosaurus, Parrosaurus, Pinacosaurus, Styracosaurus and...
, from a lower jaw collected during the late 19th century by Othniel Charles Marsh
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...
's workers at Como Bluff
Como Bluff
Como Bluff is a long ridge extending east-west, located between the towns of Rock River and Medicine Bow, Wyoming. The ridge is an anticline, formed as a result of compressional geological folding. Three geological formations, the Sundance, the Morrison, and the Cloverly Formations, containing...
. He tentatively described the genus as a lizard, noting that it could instead be a frog. New material from Europe permitted Susan Evans to reevalute it as an early choristodere in 1989. To date it is only known from fragmentary specimens. Morrison Formation Cteniogenys were 25 to 50 cm (9.8 to 19.7 in) long, and probably weighed less than 500 grams (1.1 lb). The skull of this genus was long and slender, and the jaws had numerous conical teeth. Cteniogenys in the Morrison probably fed on insects and small fish. It is mostly known from freshwater sites (rivers and ponds), and is a rare find in the formation (only 60 specimens out of over 2,800 total vertebrate specimens known from the formation), mostly known from northern outcrops (particularly 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...
). The Late Cretaceous record of this genus consists of a handful of skull and jaw fragments from the Oldman Formation
Oldman Formation
The Oldman Formation is the middle member of the Judith River Group, a major geologic unit in southern Alberta. The formation is widely recognized as bearing a great number of well preserved dinosaur skeletons, as well as other fossils.-Age:...
and Dinosaur Park Formation
Dinosaur Park Formation
The Dinosaur Park Formation is the uppermost member of the Judith River Group, a major geologic unit in southern Alberta. It was laid down over a period of time between about 76.5 and 75 million years ago. The formation is made up of deposits of a high-sinuosity fluvial system, and is capped...
. Given the long gap in time, these may represent a different, as-yet undetermined genus.