Bradysaurus
Encyclopedia
Bradysaurus was a large (2.5 to 3 meters long [8 to 10 ft]), early and common pareiasaur
, the fossils of which are known from the richly fossiliferous Tapinocephalus Assemblage Zone
(Capitanian
age) of the South African Karoo
. Along with the similarly large dinocephalia
, the bradysaurs constituted the herbivorous
megafauna
of the late Middle Permian Period. In life they were probably slow, clumsy and inoffensive animals, that had evolved a covering of armoured scutes to protect them against their predators, the gorgonopsia
ns.
s between the bones not clearly visible. The marginal teeth were high-crowned, with only a few cusps, which is a primitive characteristic.
The feet were short and broad, the phalangeal count being 2,3,3,3,2 on the fore-foot and 2,3,3,4,3 on the hind. The whole body is protected by dermal scutes, although these are not as thick or heavy as in more advanced forms.
, were no larger. The advantage of large size was to provide defense against predators and to maintain a stable body temperature (gigantothermy
).
1969 lists no fewer than nine species for this genus, but this is certainly an excessive number. Boonstra 1969 distinguishes only four species on the basis of tooth structure, two of which Kuhn places in the genus Embrithosaurus.
The genera Brachypareia, Bradysuchus, Koalemasaurus, and Platyoropha would seem to be synonyms of Bradysaurus.
The two species are as follows:
This is the type species
for the genus. The quadra-jugal region (cheek-bones) were only moderately developed. The snout was broad and rounded and there were 15 or 16 pairs of overlapping teeth in each jaw. This animal could be considered a generic early pareiasaur. According to Lee, 1997, the available material of B. baini lacks distinguishing autapomorphies
or characteristics.
Pareiasaur
The Pareiasaurs - Family Pareiasauridae - are a clade of medium-sized to large herbivorous anapsid reptiles that flourished during the Permian period....
, the fossils of which are known from the richly fossiliferous Tapinocephalus Assemblage Zone
Tapinocephalus Assemblage Zone
The Tapinocephalus Assemblage Zone is a geological stratum and is the thickest faunal zone of the Beaufort Group, in which has been found a rich variety of early therapsids. The name refers to Tapinocephalus, a genus of large herbivorous dinocephalian synapsids that lived during the Middle Permian...
(Capitanian
Capitanian
In the geologic timescale, the Capitanian is an age or stage of the Permian. It is also the uppermost or latest of three subdivisions of the Guadalupian epoch or series. The Capitanian lasted between and...
age) of the South African Karoo
Karoo
The Karoo is a semi-desert region of South Africa. It has two main sub-regions - the Great Karoo in the north and the Little Karoo in the south. The 'High' Karoo is one of the distinct physiographic provinces of the larger South African Platform division.-Great Karoo:The Great Karoo has an area of...
. Along with the similarly large dinocephalia
Dinocephalia
Dinocephalia are a clade of large early therapsids that flourished during the Middle Permian, but became extinct leaving no descendants.-Description:...
, the bradysaurs constituted the herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
megafauna
Megafauna
In terrestrial zoology, megafauna are "giant", "very large" or "large" animals. The most common thresholds used are or...
of the late Middle Permian Period. In life they were probably slow, clumsy and inoffensive animals, that had evolved a covering of armoured scutes to protect them against their predators, the gorgonopsia
Gorgonopsia
Gorgonopsia is a suborder of therapsid synapsids. Their name is a reference to the Gorgons of Greek mythology. Like other therapsids, gorgonopsians were at one time called "mammal-like reptiles"...
ns.
Characteristics
The skull was large (about 42 to 48 centimeters long [17 to 19 in]), broad and rounded at the front. It was coarsely sculptured and knobby, with the sutureSuture (anatomical)
In anatomy, a suture is a fairly rigid joint between two or more hard elements of an animal, with or without significant overlap of the elements....
s between the bones not clearly visible. The marginal teeth were high-crowned, with only a few cusps, which is a primitive characteristic.
The feet were short and broad, the phalangeal count being 2,3,3,3,2 on the fore-foot and 2,3,3,4,3 on the hind. The whole body is protected by dermal scutes, although these are not as thick or heavy as in more advanced forms.
Classification
Bradysaurus is the only member of the subfamily Bradysaurinae. It is the most primitive known pareiasaur and can be considered a good ancestral type from which the others developed. Its large dimensions show that, even very early in their evolutionary history, these strange animals had already attained an optimal size. Even later, more advanced forms, like ScutosaurusScutosaurus
Scutosaurus was a genus of armor-covered pareiasaur that lived around 252-248 million years ago in Russia, in the later Permian period. Its genus name refers to large plates of armor scattered across its body...
, were no larger. The advantage of large size was to provide defense against predators and to maintain a stable body temperature (gigantothermy
Gigantothermy
Gigantothermy is a phenomenon with significance in biology and paleontology, whereby large, bulky ectothermic animals are more easily able to maintain a constant, relatively high body temperature than smaller animals by virtue of their smaller surface area to volume ratio...
).
Species
KuhnOskar Kuhn
Oskar Kuhn was a German palaeontologist.-Life and career:Kuhn was educated in Dinkelsbühl and Bamberg and then studied natural science, specialising in geology and paleontology, at the University of Munich, from which he received his D. Phil...
1969 lists no fewer than nine species for this genus, but this is certainly an excessive number. Boonstra 1969 distinguishes only four species on the basis of tooth structure, two of which Kuhn places in the genus Embrithosaurus.
The genera Brachypareia, Bradysuchus, Koalemasaurus, and Platyoropha would seem to be synonyms of Bradysaurus.
The two species are as follows:
Bradysaurus baini (Seeley 1892)
- Tapinocephalus zone, Lower Beaufort Beds, Karoo basin, South Africa
This is 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...
for the genus. The quadra-jugal region (cheek-bones) were only moderately developed. The snout was broad and rounded and there were 15 or 16 pairs of overlapping teeth in each jaw. This animal could be considered a generic early pareiasaur. According to Lee, 1997, the available material of B. baini lacks distinguishing 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...
or characteristics.
Bradysaurus seeleyi Haughton and Boonstra 1929
- Tapinocephalus zone, Lower Beaufort Beds, Karoo basin, South Africa. This is a less common form. Boonstra, 1969, considered this a valid species of Bradysaurus and Lee, 1997, considers this animal a sister group to more advanced pareiasaurs. B. seelyi seems to be closely related to Nochelesaurus and EmbrithosaurusEmbrithosaurusEmbrithosaurus was a pareiasaur from the Permian time period.-Embrithosaurus schwarzi:Embrithosaurus schwarzi is the type species of Embrithosaurus...
. In contrast to the more numerous but similarly sized B. baini, the cheekbones were heavy and greatly enlarged. There were 19 or 20 pairs of strongly overlapping teeth on each jaw.
External links
- Palaeos Bradysaurs