Phyllodontosuchus
Encyclopedia
Phyllodontosuchus is a genus
of sphenosuchia
n, a type of basal
crocodylomorph
, the clade
that comprises the crocodilians and their closest kin. It is known from a skull and jaws from Lower Jurassic rocks of Yunnan
, China
. Phyllodontosuchus is unusual because some of its teeth were leaf-shaped, like those of some herbivorous dinosaur
s, and it does not appear to have been a strict carnivore
like most other crocodylomorphs.
BVP568
-L12, a crushed skull and jaws recovered from the Sinemurian
-age Dark Red Beds of the Lufeng Formation
near Dawa in Yunnan. A Morganucodon
skull was also recovered from this locality. BVP568-L12 is only 71.4 millimetres (2.8 in) long and imperfectly preserved; it was first thought to represent an early ornithischia
n dinosaur. Sutures are not visible, so despite the small size, the specimen appears to have come from an adult. Phyllodontosuchus was named in 2000 by Jerald Harris and colleagues. The type species
is P. lufengensis, in reference to the Lufeng Formation.
There were 17 or 18 teeth per side in the upper jaw, which differed in shape
depending on where they were in the jaw (heterodont
y). The first five or six were pointed, conical, and curved backward. The following twelve were leaf- or spade-shaped, with fine crenelations on the trailing edge. These are similar to the teeth of some prosauropods and early ornithischians, but differ in important features. For example, the teeth lacked the swellings and ridges seen in the teeth of early ornithischians like Lesothosaurus
, and the coarse denticles (smaller points) of leaf-shaped ornithischian and prosauropod teeth in general. Phyllodontosuchus also lacked a predentary
as found in all known ornithischians. Instead, it is most similar to sphenosuchians.
Heterodonty is known in several sphenosuchians, including Dibothrosuchus
, Hesperosuchus
, Pedeticosaurus
, and Sphenosuchus
. These forms had similar divisions of pointed and recurved anterior teeth and less pointed middle and posterior teeth, which could have been the ancestral state for the leaf-shaped teeth of Phyllodontosuchus. Small heterodont crocodylomorphs are known from other lineages as well, including Edentosuchus
, Chimaerasuchus
, and Malawisuchus
. These small, variably-toothed crocodylomorphs are thought to have had diets beyond the typical carnivory/piscivory
of modern crocodilians, possibly including some degree of herbivory. If Phyllodontosuchus did eat plants, it probably did not grind them in the jaws, though.
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 sphenosuchia
Sphenosuchia
Sphenosuchia is a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Late Jurassic. Most were small, gracile animals with an erect limb posture. They are now thought to be ancestral to crocodyliforms, which include all living crocodilians.-Stratigraphic...
n, a type of basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
crocodylomorph
Crocodylomorpha
The Crocodylomorpha are an important group of archosaurs that include the crocodilians and their extinct relatives.During Mesozoic and early Tertiary times the Crocodylomorpha were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. These were...
, the clade
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...
that comprises the crocodilians and their closest kin. It is known from a skull and jaws from Lower Jurassic rocks of Yunnan
Yunnan
Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...
, China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. Phyllodontosuchus is unusual because some of its teeth were leaf-shaped, like those of some herbivorous 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, and it does not appear to have been a strict carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
like most other crocodylomorphs.
History and description
Phyllodontosuchus is based onHolotype
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...
BVP568
Beijing Museum of Natural History
The Beijing Museum of Natural History is located at 126, Tian Qiao Nan Street, Chong Wen District, Beijing, 100050, and is the most popular natural history museum in China. It was originally founded in 1951 as the National Central Museum of Natural History, and its name changed to the Beijing...
-L12, a crushed skull and jaws recovered from the Sinemurian
Sinemurian
In the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
-age Dark Red Beds of the Lufeng Formation
Lower Lufeng Series
The Lower Lufeng Series is a Lower Jurassic sedimentary rock formation found in Yunnan, China. It has two units: the lower Dull Purplish Beds are of Hettangian age, and Dark Red Beds are of Sinemurian age. It is known for its fossils of early dinosaurs...
near Dawa in Yunnan. A Morganucodon
Morganucodon
Morganucodon is an early mammalian genus which lived during the Late Triassic. It first appeared about 205 million years ago. This has also been identified with Eozostrodon. Unlike many other early mammals, Morganucodon is well represented by abundant and well preserved, though in the vast...
skull was also recovered from this locality. BVP568-L12 is only 71.4 millimetres (2.8 in) long and imperfectly preserved; it was first thought to represent an early ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
n dinosaur. Sutures are not visible, so despite the small size, the specimen appears to have come from an adult. Phyllodontosuchus was named in 2000 by Jerald Harris and colleagues. 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 P. lufengensis, in reference to the Lufeng Formation.
There were 17 or 18 teeth per side in the upper jaw, which differed in shape
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....
depending on where they were in the jaw (heterodont
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...
y). The first five or six were pointed, conical, and curved backward. The following twelve were leaf- or spade-shaped, with fine crenelations on the trailing edge. These are similar to the teeth of some prosauropods and early ornithischians, but differ in important features. For example, the teeth lacked the swellings and ridges seen in the teeth of early ornithischians like Lesothosaurus
Lesothosaurus
Lesothosaurus is an herbivorous ornithischian dinosaur. It was named by paleontologist Peter Galton in 1978, the name meaning "lizard from Lesotho". The genus is monotypic, having only one valid species, Lesothosaurus diagnosticus, within the genus....
, and the coarse denticles (smaller points) of leaf-shaped ornithischian and prosauropod teeth in general. Phyllodontosuchus also lacked a predentary
Predentary
The predentary is an 'extra' bone in the front of the lower jaw, which extended the dentary . It is found in the fossilised remains of ornithischian dinosaurs, which were herbivorous. The predentary coincided with the premaxilla in the upper jaw. Together they formed a beak-like apparatus used to...
as found in all known ornithischians. Instead, it is most similar to sphenosuchians.
Heterodonty is known in several sphenosuchians, including Dibothrosuchus
Dibothrosuchus
Dibothrosuchus is a genus of sphenosuchian, a type of basal crocodylomorph, the clade that comprises the crocodilians and their closest kin. It is known from several partial skeletons and skulls. These fossils were found in Lower Jurassic rocks of Yunnan, China...
, Hesperosuchus
Hesperosuchus
Hesperosuchus is an extinct genus of crocodylomorph reptile that contains a single species, Hesperosuchus agilis. Remains of this sphenosuchian have been found in Late Triassic strata from Arizona and New Mexico....
, Pedeticosaurus
Pedeticosaurus
Pedeticosaurus is an extinct genus of sphenosuchian crocodylomorph from the Clarens Formation of South Africa. The type species is P. leviseuri....
, and Sphenosuchus
Sphenosuchus
Sphenosuchus is an extinct genus of sphenosuchian from the Elliot Formation of South Africa, discovered and described early in the 20th century. The skull is excellently preserved but other than elements of the forelimb and isolated parts of the hind limb, the Sphenosuchus material is incomplete...
. These forms had similar divisions of pointed and recurved anterior teeth and less pointed middle and posterior teeth, which could have been the ancestral state for the leaf-shaped teeth of Phyllodontosuchus. Small heterodont crocodylomorphs are known from other lineages as well, including Edentosuchus
Edentosuchus
Edentosuchus is a genus of protosuchian crocodylomorph. It is known from fossils found in rocks of the Early Cretaceous-age Tugulu Group from the Junggar Basin, Xinjiang, China. Two partial skulls and several neck vertebrae are known to date...
, Chimaerasuchus
Chimaerasuchus
Chimaerasuchus is an extinct genus of Chinese crocodyliform from the Early Cretaceous. The four teeth in the very tip of its short snout gave it a "bucktoothed" appearance. Due its multicusped teeth and marked heterodonty, it is believed to have been an herbivore....
, and Malawisuchus
Malawisuchus
Malawisuchus is an extinct genus of notosuchian mesoeucrocodylian from the Early Cretaceous of Malawi. It was described in 1997 by Elizabeth Gomani as a member of the family Notosuchidae. The type species is M. mwakasyungutiensis, referring to Mwakasyunguti, the area of northern Malawi where it...
. These small, variably-toothed crocodylomorphs are thought to have had diets beyond the typical carnivory/piscivory
Piscivore
A piscivore is a carnivorous animal which eats primarily fish. Piscivory was the diet of early tetrapods , insectivory came next, then in time reptiles added herbivory....
of modern crocodilians, possibly including some degree of herbivory. If Phyllodontosuchus did eat plants, it probably did not grind them in the jaws, though.