Ceratosauridae
Encyclopedia
Ceratosauridae is a family
of theropod dinosaur
s belonging to the infraorder Ceratosauria
. Its type genus, Ceratosaurus
, was first found in Jurassic
rocks from North America
. Ceratosauridae is made up of Ceratosaurus, found in North America, Tanzania
, and Portugal
, and Genyodectes
, from the Late Cretaceous
of Argentina
. Unnamed probable ceratosaurids are known from limited material from the Middle Jurassic
of Madagascar
, the Late Jurassic
of Switzerland
, and the Late Jurassic or possibly Early Cretaceous
of Uruguay
.
named the family Ceratosauridae in 1884 to contain the type species
, Ceratosaurus nasicornis. Since then, a number of other species have been referred to this family, mainly from the genus
Ceratosaurus. Currently recognized ceratosaurid species include Ceratosaurus ingens, C. dentisulcatus, C. magnicornis, and Genyodectes serus. No cladistic definition of Ceratosauridae has been proposed.
Due to the paucity of remains of Genyodectes, it is difficult to discern possible synapomorphies
of the group from autapomorphies
of Ceratosaurus; e.g. Ceratosaurus is different from other ceratosaurians by the very prominent horn
on its snout; Genyodectes, however, was not found with a complete skull
; whether it had a horn is unknown, so it cannot establish that the horn was a shared derived feature of the group.
There are two known types of Ceratosaurus teeth: one with longitudinal ridges and the other with smooth enamel
. Both types of teeth have crowns with a teardrop-shaped cross section and carinae running up the middle. The cross section of the tooth's base depends on the position of the tooth in the mouth with front teeth having less symmetric cross sections.
and Tendaguru
put the Ceratosauridae family in the presence of other large predators. In North America, it is likely that members of the family such as C. nasicornis competed with allosaurs
(A. fragilis) for food, such as sauropods common to the region at the time. In Africa
and Europe
members also competed with other large predators for similar food sources. The presence of C. nasicornis at the Cleveland Lloyd Dinosaur Quarry
along with the remains of several allosaurids is a good indication of just how close members of this family and other predators coexisted.
Note: Dry Mesa Quarry and Cleveland Lloyd Dinosaur Quarry are part of the Morrison Formation
Family
In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children...
of theropod 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...
s belonging to the infraorder Ceratosauria
Ceratosauria
Ceratosaurs are members of a group of theropod dinosaurs defined as all theropods sharing a more recent common ancestry with Ceratosaurus than with birds. There is presently no universally agreed upon listing of species or diagnostic characters of Ceratosauria, though they were less derived...
. Its type genus, Ceratosaurus
Ceratosaurus
Ceratosaurus meaning "horned lizard", in reference to the horn on its nose , was a large predatory theropod dinosaur from the Late Jurassic Period , found in the Morrison Formation of North America, in Tanzania and Portugal...
, was first found in 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...
rocks from 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...
. Ceratosauridae is made up of Ceratosaurus, found in North America, Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
, and Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
, and Genyodectes
Genyodectes
Genyodectes is a genus of ceratosaurian theropod dinosaur from the Lower Cretaceous of South America. The holotype material was collected from the Cañadón Grande, Departamento Paso de Indios in the Chubut Province of Argentina and consists of an incomplete snout, including the premaxillae,...
, from 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 Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. Unnamed probable ceratosaurids are known from limited material 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....
of Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
, 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...
of Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
, and the Late Jurassic or possibly Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
of Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
.
Classification
Othniel Charles MarshOthniel 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...
named the family Ceratosauridae in 1884 to contain 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...
, Ceratosaurus nasicornis. Since then, a number of other species have been referred to this family, mainly from 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...
Ceratosaurus. Currently recognized ceratosaurid species include Ceratosaurus ingens, C. dentisulcatus, C. magnicornis, and Genyodectes serus. No cladistic definition of Ceratosauridae has been proposed.
Features
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...
of the group from autapomorphies
Autapomorphy
In cladistics, an autapomorphy is a distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group. That is, it is found only in one member of a clade, but not found in any others or outgroup taxa, not even those most closely related to the group...
of Ceratosaurus; e.g. Ceratosaurus is different from other ceratosaurians by the very prominent horn
Horn (anatomy)
A horn is a pointed projection of the skin on the head of various animals, consisting of a covering of horn surrounding a core of living bone. True horns are found mainly among the ruminant artiodactyls, in the families Antilocapridae and Bovidae...
on its snout; Genyodectes, however, was not found with a complete 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...
; whether it had a horn is unknown, so it cannot establish that the horn was a shared derived feature of the group.
There are two known types of Ceratosaurus teeth: one with longitudinal ridges and the other with smooth enamel
Tooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
. Both types of teeth have crowns with a teardrop-shaped cross section and carinae running up the middle. The cross section of the tooth's base depends on the position of the tooth in the mouth with front teeth having less symmetric cross sections.
Environment
Being found in the MorrisonMorrison 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...
and Tendaguru
Tendaguru
The Tendaguru Beds are a fossil-rich formation in Tanzania. It has been considered the richest of Late Jurassic strata in Africa. Continental reconstructions show Tendaguru to have been in the southern hemisphere during the Late Jurassic. Tendaguru is similar to the Morrison Formation except in...
put the Ceratosauridae family in the presence of other large predators. In North America, it is likely that members of the family such as C. nasicornis competed with allosaurs
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...
(A. fragilis) for food, such as sauropods common to the region at the time. In Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and 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...
members also competed with other large predators for similar food sources. The presence of C. nasicornis at the Cleveland Lloyd Dinosaur Quarry
Cleveland Lloyd Dinosaur Quarry
The Cleveland Lloyd Dinosaur Quarry National Natural Landmark, located in The San Rafael Swell, near Cleveland, Utah contains the densest concentration of Jurassic dinosaur fossils ever found. Well over 15,000 bones have been excavated from this Jurassic 'predator trap' and there are many...
along with the remains of several allosaurids is a good indication of just how close members of this family and other predators coexisted.
Sites containing ceratosaurids
- Dry Mesa QuarryDry Mesa QuarryThe Dry Mesa Dinosaur Quarry is situated in southwestern Colorado, USA, near the town of Delta. Its geology forms a part of the Morrison Formation and has famously yielded a great diversity of animal remains from the Jurassic Period, among them Ceratosaurus, Supersaurus, and Torvosaurus...
, ColoradoColoradoColorado 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...
/USA (Ceratosaurus) - Cleveland Lloyd Dinosaur QuarryCleveland Lloyd Dinosaur QuarryThe Cleveland Lloyd Dinosaur Quarry National Natural Landmark, located in The San Rafael Swell, near Cleveland, Utah contains the densest concentration of Jurassic dinosaur fossils ever found. Well over 15,000 bones have been excavated from this Jurassic 'predator trap' and there are many...
, UtahUtahUtah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
/USA (Ceratosaurus) - TendaguruTendaguruThe Tendaguru Beds are a fossil-rich formation in Tanzania. It has been considered the richest of Late Jurassic strata in Africa. Continental reconstructions show Tendaguru to have been in the southern hemisphere during the Late Jurassic. Tendaguru is similar to the Morrison Formation except in...
, Mtwara RegionMtwara RegionMtwara is a southern region of Tanzania which has been underdeveloped for a long time: development is constrained by the lack of highway and energy infrastructures. The Dar es Salaam-Kibiti-Lindi-Mtwara road has been improved by the completion of the Mkapa bridge over the Rufiji River...
/TanzaniaTanzaniaThe United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
(Ceratosaurus) - New Amoreira- Porto Fomation, PortugalPortugalPortugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
(Ceratosaurus) - Cañadón Grande, Chabut Province/ArgentinaArgentinaArgentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
(Genyodectes)
Note: Dry Mesa Quarry and Cleveland Lloyd Dinosaur Quarry are part of the 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...