Ceratosuchus
Encyclopedia
Ceratosuchus is an extinct genus
of alligatorine
from latest Paleocene
rocks of Colorado
's Piceance Basin
and earliest Eocene
rocks of Wyoming
's Bighorn Basin
in North America
, a slice of time known as the Clarkforkian
North American Land Mammal Age. Like its modern relatives, Ceratosuchus was a swamp-dwelling predator. It is named for the pair of flattened, triangular bony
plates that extend from the back of its head. The type species
is C. burdoshi.
s, and cervical
armor
, was recovered from Wyoming by University of Michigan
paleontologists and described by William Bartels in 1984. The skull, of a moderately-size alligatorine, is most notable for its horns, formed by expansion of the bones (squamosal
s) that formed the rear corners of the skull roof. These horns were bulbous and pointed up. There were five teeth in both of the bones that made up the tip of the snout (premaxilla
), fifteen in the paired maxilla
e that formed the sides of the upper jaw, and twenty in both dentaries of the lower jaw. The front of the lower jaw had a flattened shape, and the teeth located here pointed partially forward, with a spade
-like form. The teeth had variable shapes
; the first thirteen teeth in the lower jaw were pointed, while the last seven graded from a spatula
te shape to a large globular shape. Aside from the horns, the skull and particularly the lower jaw of Ceratosuchus were very similar to that of its contemporary Allognathosuchus
. The neck armor had blade-like keels that may have been aligned with the skull horns.
, C. robustus and C. rhombifer. Bartels proposed that the horns' small size and bluntness made them unlikely weapons, and their small size also made use in a threat display unlikely. Instead, he favored their use as signals for species recognition: in this case, the horns would allow Ceratosuchus and species of Allognathosuchus to tell each other apart.
Ceratosuchus is known from overbank mudstone
deposits. It so far has been a rare find compared to Allognathosuchus from the same rocks. Bartels reported that only 5% of Clarkforkian crocodilians collected by the University of Michigan can be certainly assigned to Ceratosuchus (although this may be partially artificial because fragmentary specimens of Ceratosuchus could be confused with Allognathosuchus). Ceratosuchus may have been ecologically
restricted in comparison to Allognathosuchus.
Although the blunt posterior teeth of Allognathosuchus and Ceratosuchus have been traditionally interpreted as for feeding on mollusks
or turtle
s, Bartels noted that these crocodilians were too small to feed on large bivalves or non-juvenile turtles, and that modern crocodilians usually swallow snail
s whole. Instead, he proposed that skull morphology
and tooth wear better fit generalized predation
on a variety of invertebrates and vertebrates.
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 alligatorine
Alligatoridae
Alligatoridae is a family of crocodylians that includes alligators and caimans.- True alligators :Alligators proper occur in the fluvial deposits of the age of the Upper Chalk in Europe, where they did not die out until the Pliocene age. The true alligators are now restricted to two species, A...
from latest Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
rocks of 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...
's Piceance Basin
Piceance Basin
The Piceance Basin is a geologic structural basin in northwestern Colorado, in the United States. It includes geologic formations from Cambrian to Holocene in age, but the thickest section is made up of rocks from the Cretaceous Period...
and earliest Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
rocks of 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...
's Bighorn Basin
Bighorn Basin
The Bighorn Basin is a plateau region and intermontane basin, approximately 100 miles wide, in north-central Wyoming in the United States. It is bounded by the Absaroka Range on the west, the Bighorn Mountains on the east, and the Owl Creek Mountains and Bridger Mountains on the south...
in 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...
, a slice of time known as the Clarkforkian
Clarkforkian
The Clarkforkian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 56,800,000 to 55,400,000 years BP lasting . It is usually considered to be within the Paleocene, more specifically the...
North American Land Mammal Age. Like its modern relatives, Ceratosuchus was a swamp-dwelling predator. It is named for the pair of flattened, triangular bony
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
plates that extend from the back of its head. 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...
is C. burdoshi.
Description
Ceratosuchus was named in 1938 by K. P. Schmidt for a skull from Colorado. Further remains, including skulls, mandibleMandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
s, and cervical
Neck
The neck is the part of the body, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso or trunk. The adjective signifying "of the neck" is cervical .-Boner anatomy: The cervical spine:The cervical portion of the human spine comprises seven boney...
armor
Osteoderm
Osteoderms are bony deposits forming scales, plates or other structures in the dermal layers of the skin. Osteoderms are found in many groups of extant and extinct reptiles, including lizards, various groups of dinosaurs , crocodilians, phytosaurs, aetosaurs, placodonts, and hupehsuchians...
, was recovered from Wyoming by University of Michigan
University of Michigan
The University of Michigan is a public research university located in Ann Arbor, Michigan in the United States. It is the state's oldest university and the flagship campus of the University of Michigan...
paleontologists and described by William Bartels in 1984. The skull, of a moderately-size alligatorine, is most notable for its horns, formed by expansion of the bones (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,...
s) that formed the rear corners of the skull roof. These horns were bulbous and pointed up. There were five teeth in both of the bones that made up the tip of the snout (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....
), fifteen in the paired maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
e that formed the sides of the upper jaw, and twenty in both dentaries of the lower jaw. The front of the lower jaw had a flattened shape, and the teeth located here pointed partially forward, with a spade
Spade
A spade is a tool designed primarily for the purpose of digging or removing earth. Early spades were made of riven wood. After the art of metalworking was discovered, spades were made with sharper tips of metal. Before the advent of metal spades manual labor was less efficient at moving earth,...
-like form. The teeth had variable shapes
Heterodont
The anatomical term heterodont refers to animals which possess more than a single tooth morphology. For example, members of the Synapsida generally possess incisors, canines , premolars, and molars. The presence of heterodont dentition is evidence of some degree of feeding/hunting specialization...
; the first thirteen teeth in the lower jaw were pointed, while the last seven graded from a spatula
Spatula
The term spatula is used to refer to various small implements with a broad, flat, flexible blade used to mix, spread and lift materials including foods, drugs, plaster and paints...
te shape to a large globular shape. Aside from the horns, the skull and particularly the lower jaw of Ceratosuchus were very similar to that of its contemporary Allognathosuchus
Allognathosuchus
Allognathosuchus is an extinct genus of alligatorine crocodylian with a complicated taxonomic history. This small alligatorine is known for its stout jaws and bulbous teeth, found near the rear of the tooth row in upper and lower jaws. These adaptations have historically been interpreted as...
. The neck armor had blade-like keels that may have been aligned with the skull horns.
Paleobiology
Although Ceratosuchus is the only known horned alligatorine, horns are not unknown in crocodilians; similar structures are known for two species of CrocodylusCrocodylus
Crocodylus is one of three genera from the Crocodylinae subfamily extending from the Crocodylidae family.Established species include three extinct species:* † Crocodylus acer - probably represents a distinct genus....
, C. robustus and C. rhombifer. Bartels proposed that the horns' small size and bluntness made them unlikely weapons, and their small size also made use in a threat display unlikely. Instead, he favored their use as signals for species recognition: in this case, the horns would allow Ceratosuchus and species of Allognathosuchus to tell each other apart.
Ceratosuchus is known from overbank mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
deposits. It so far has been a rare find compared to Allognathosuchus from the same rocks. Bartels reported that only 5% of Clarkforkian crocodilians collected by the University of Michigan can be certainly assigned to Ceratosuchus (although this may be partially artificial because fragmentary specimens of Ceratosuchus could be confused with Allognathosuchus). Ceratosuchus may have been ecologically
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
restricted in comparison to Allognathosuchus.
Although the blunt posterior teeth of Allognathosuchus and Ceratosuchus have been traditionally interpreted as for feeding on mollusks
Mollusca
The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest...
or turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s, Bartels noted that these crocodilians were too small to feed on large bivalves or non-juvenile turtles, and that modern crocodilians usually swallow snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s whole. Instead, he proposed that skull morphology
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....
and tooth wear better fit generalized predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
on a variety of invertebrates and vertebrates.