The ''Tapinocephalus'' Assemblage Zone is a
tetrapod
Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...
assemblage zone or
biozone which correlates to the middle
Abrahamskraal Formation
The Abrahamskraal Formation is a geological formation and is found in numerous localities in the Northern Cape, Western Cape, and the Eastern Cape of South Africa. It is the lowermost formation of the Adelaide Subgroup of the Beaufort Group, a ma ...
, Adelaide Subgroup of the
Beaufort Group
The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underli ...
, a fossiliferous and geologically important geological
Group of the
Karoo Supergroup
The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a peri ...
in
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...
. The thickest
outcrop
An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth.
Features
Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficia ...
s, reaching approximately , occur from
Merweville and
Leeu-Gamka in its southernmost exposures, from
Sutherland
Sutherland ( gd, Cataibh) is a historic county, registration county and lieutenancy area in the Highlands of Scotland. Its county town is Dornoch. Sutherland borders Caithness and Moray Firth to the east, Ross-shire and Cromartyshire (later c ...
through to
Beaufort West
Beaufort West (Afrikaans: ''Beaufort-Wes''; Xhosa: ''eBhofolo'') is a town in the Western Cape province in South Africa. It is the largest town in the arid Great Karoo region, and is known as the "Capital of the Karoo". It forms part of the Beau ...
where outcrops start to only be found in the south-east, north of
Oudshoorn
Oudshoorn is a former village in the Netherlands, Dutch province of South Holland. It was located on the Oude Rijn (Utrecht and South Holland), Oude Rijn, opposite the village of Alphen (South Holland), Alphen, with which it merged to form the cit ...
and
Willowmore, reaching up to areas south of
Graaff-Reinet. Its northernmost exposures occur around the towns
Fraserburg and
Victoria West. The ''Tapinocephalus Assemblage Zone'' is the second
biozone of the
Beaufort Group
The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underli ...
.
The name of the
biozone refers to ''
Tapinocephalus atherstonei'', a large
herbivorous
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...
tapinocephalid
Tapinocephalidae was an advanced family of tapinocephalians. It is defined as the clade containing ''Ulemosaurus'', '' Tapinocaninus'', and the Tapinocephalinae. They are known from both Russia and South Africa. In all probability, the Tapinoceph ...
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
n
therapsid
Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more ...
. It is characterised by the presence of this
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
n species along with the appearance of other advanced
tapinocephalid
Tapinocephalidae was an advanced family of tapinocephalians. It is defined as the clade containing ''Ulemosaurus'', '' Tapinocaninus'', and the Tapinocephalinae. They are known from both Russia and South Africa. In all probability, the Tapinoceph ...
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
ns, and the large
pareiasaur
Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with scutes which covered large areas of the body. They first appeared in southern Pangea during the Middle Permi ...
''
Bradysaurus baini
''Bradysaurus'' was a large, early and common pareiasaur, the fossils of which are known from the ''Tapinocephalus'' Assemblage Zone (Capitanian age) of the South African Karoo. Along with the similarly large dinocephalia, the bradysaurs consti ...
''. It is also the first biozone of the series where the
dicynodont
Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typic ...
, ''
Diictodon feliceps,'' species first appear.
History
The first
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s to be found in the
Beaufort Group
The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underli ...
rocks that encompass the current eight
biozones were discovered by
Andrew Geddes Bain in 1856. However, it was not until 1892 that it was observed that the geological strata of the
Beaufort Group
The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underli ...
could be differentiated based on their
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
. The initial undertaking was done by
Harry Govier Seeley who subdivided the
Beaufort Group
The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underli ...
into three
biozones, which he named (from oldest to youngest):
* Zone of "
Pareiasaur
Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with scutes which covered large areas of the body. They first appeared in southern Pangea during the Middle Permi ...
ians"
* Zone of "
Dicynodont
Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typic ...
s"
* Zone of "highly specialized group of
theriodonts"
These proposed biozones
Seeley named were subdivided further by
Robert Broom
Robert Broom FRS FRSE (30 November 1866 6 April 1951) was a British- South African doctor and palaeontologist. He qualified as a medical practitioner in 1895 and received his DSc in 1905 from the University of Glasgow.
From 1903 to 1910, he ...
between 1906 and 1909.
Broom
A broom (also known in some forms as a broomstick) is a cleaning tool consisting of usually stiff fibers (often made of materials such as plastic, hair, or corn husks) attached to, and roughly parallel to, a cylindrical handle, the broomstick. I ...
proposed the following
biozones (from oldest to youngest):
* ''
Pareiasaurus'' beds
* ''
Endothiodon'' beds
* ''
Kistecephalus'' beds
* ''
Lystrosaurus'' beds
* ''
Procolophon'' beds
* ''
Cynognathus'' beds
The rocks of the current ''Tapinocephalus'' Assemblage Zone were first included with those of the lower
''Eodicynodon'' Assemblage Zone under the name "Pareiasaurus beds" by
Broom
A broom (also known in some forms as a broomstick) is a cleaning tool consisting of usually stiff fibers (often made of materials such as plastic, hair, or corn husks) attached to, and roughly parallel to, a cylindrical handle, the broomstick. I ...
. Years later
Lieuwe Dirk Boonstra
Lieuwe Dirk Boonstra (1905 – 1975) was a South African palaeontologist whose work focused on the therapsida, mammal-like reptiles of the Middle ( Tapinocephalus Assemblage Zone, ''Tapinocephalus'' Assemblage Zone) and Late Permian, whose fossil ...
redefined the boundaries of the ''Tapinocephalus'' Assemblage Zone. As a young man
Boonstra collaborated with
Broom
A broom (also known in some forms as a broomstick) is a cleaning tool consisting of usually stiff fibers (often made of materials such as plastic, hair, or corn husks) attached to, and roughly parallel to, a cylindrical handle, the broomstick. I ...
on research of
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
ns. After embarking on further study of dinocephalian fossils and their biostratigraphy,
Boonstra defined the lower, middle, and upper sections of this biozone. In the 1970s, Keyser and Smith proposed the renaming of the
biozone to
Dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
n Assemblage Zone. In 1984
James Kitching proposed to name the
biozone after ''
Tapinocephalus,'' which was accepted over Keyser and Smith’s proposal. However, the zoning of the
biozone rocks remains as they were defined by Keyser and Smith.
Lithology
The ''Tapinocephalus'' Assemblage Zone correlates with the
Abrahamskraal Formation
The Abrahamskraal Formation is a geological formation and is found in numerous localities in the Northern Cape, Western Cape, and the Eastern Cape of South Africa. It is the lowermost formation of the Adelaide Subgroup of the Beaufort Group, a ma ...
, Adelaide Subgroup of the
Beaufort Group
The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underli ...
. Outcrops of this biozone are known from the south-western and central margins of the Abrahamskraal Formation where it
conformably
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology.
In general, strata are primarily i ...
overlies the
''Eodicynodon'' Assemblage Zone in its south-western localities. In its northern and eastern localities it inter-fingers with
Ecca Group-aged
deposits. This
biozone is considered to be Middle
Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleo ...
(Guadalupian) in age.
The rocks of the ''Tapinocephalus'' Assemblage Zone consist mainly of maroon to greyish red or purple
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.' ...
layers which exhibit blocky weathering at exposed
outcrop
An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth.
Features
Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficia ...
s. The
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.' ...
s contain
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an ad ...
nodules and sheet
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...
s, both are indicative of a warm and seasonally
arid
A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ...
climate, revealing the presence of paleocalcretes and
carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...
precipitation respectively in
playa lakes.
Paleosol
In the geosciences, paleosol (''palaeosol'' in Great Britain and Australia) is an ancient soil that formed in the past. The precise definition of the term in geology and paleontology is slightly different from its use in soil science.
In geolo ...
s are also commonly found in the
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.' ...
s, which indicates a lack of deposition for long periods of time. In some deposits the
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.' ...
layers contain thin
chert
Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a ...
lenses which have been attributed to
silicified
In geology, petrifaction or petrification () is the process by which organic material becomes a fossil through the replacement of the original material and the filling of the original pore spaces with minerals. Petrified wood typifies this p ...
tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock ...
deposits. Alternating beds of light grey to dark greenish grey
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...
and greenish grey to light olive grey
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicat ...
s which weather to light orange grey. The
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...
s frequently contain both symmetrical and asymmetrical
ripple surfaces which indicate that
paleocurrents traveled downstream in a northerly direction.
Desiccation
Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container.
...
cracks which are infilled by fine
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicat ...
are also found. The
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicat ...
s are fine-grained and mainly tabular, indicating that deposition of these
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicat ...
s was in a low-energy
fluvial
In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...
environment. The
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicat ...
s are capped in the upper sections of the
biozone with
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.' ...
clast conglomerates.
The depositional environment of the ''Tapinocephalus'' Assemblage Zone was formed by
sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...
ary material being deposited in the
Karoo Basin
The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a perio ...
(a
retro-arc foreland basin
A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithosphere ...
) by vast, low-energy
alluvial
Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. ...
plains flowing northwards from a southerly source area in the rising
Gondwanide mountains. The
Gondwanides were the result of
crustal uplift that had previously begun to take course due to
subduction
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...
of the Palaeo-pacific plate beneath the
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final sta ...
n Plate.
Orogenic pulses from the growing Gondwanides mountain chain and associated
subduction
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...
created accommodation space for
sedimentation
Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to the ...
in the Karoo Basin where the deposits of the ''Tapinocephalus'' Assemblage zone, and all other succeeding assemblage zone deposits, were deposited over millions of years.
Paleontology
The ''Tapinocephalus'' Assemblage Zone is characterized by the presence of ''
Tapinocephalus atherstonei'' and ''
Bradysaurus baini
''Bradysaurus'' was a large, early and common pareiasaur, the fossils of which are known from the ''Tapinocephalus'' Assemblage Zone (Capitanian age) of the South African Karoo. Along with the similarly large dinocephalia, the bradysaurs consti ...
''.
Vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with ...
fossils found in this
biozone are not especially common, however are most commonly discovered as articulated single specimens within or associated with the
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an ad ...
nodules in the
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.' ...
layers. As the name for this biozone suggests, it is renowned by paleontologists for its diverse
Dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
n fossil species where almost all members of this family – the
Anteosauridae
Anteosauridae is an extinct family of large carnivorous dinocephalian therapsids that are known from the Middle Permian of Asia, Africa, and South America.These animals were by far the largest predators of the Permian period, with skulls reaching ...
,
Titanosuchidae, and
Tapinocephalidae
Tapinocephalidae was an advanced family of tapinocephalians. It is defined as the clade containing '' Ulemosaurus'', ''Tapinocaninus'', and the Tapinocephalinae. They are known from both Russia and South Africa. In all probability, the Tapinocep ...
– are represented. Example species from these families are ''
Anteosaurus magnificus
''Anteosaurus'' (meaning " Antaeus reptile") is an extinct genus of large carnivorous dinocephalian synapsid. It lived at the end of the Guadalupian (= Middle Permian) during the Capitanian stage, about 265 to 260 million years ago in what is ...
'', ''
Jonkeria boonstrai'', and ''
Tapinocephalus atherstonei'' respectively. Other notable
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
n species which have been discovered from this biozone are the advanced
tapinocephalids ''
Struthiocephalus
''Struthiocephalus'' ("Ostrich Head") is an extinct genus of dinocephalian therapsids from the Permian of South Africa. It was a large animal, reaching in body mass.
Ecology
This animal has the largest head of any tapinocephalid. Brink (195 ...
whaitsi'' and ''
Moschops
''Moschops'' (Greek for "calf face") is an extinct genus of therapsids that lived in the Guadalupian epoch, around 265–260 million years ago. They were heavily built plant eaters, and they may have lived partly in water, as hippopotamuses do. ...
capensis'', and the unusual ''
Styracocephalus platyrhynchus''. Unfortunately
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
n fossils are frequently found disarticulated with much of their
postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...
missing.
Despite the rarity of fossils, the fossil
taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
that have been found from the ''Tapinocephalus'' Assemblage Zone are extremely diverse.
Parareptile species such as the
pareiasaur
Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with scutes which covered large areas of the body. They first appeared in southern Pangea during the Middle Permi ...
, ''
Bradysaurus,'' and the perplexing putative
pantestudine ''
Eunotosaurus africanus'' are confined to this biozone. One of the few
pelycosaur
Pelycosaur ( ) is an older term for basal or primitive Late Paleozoic synapsids, excluding the therapsids and their descendants. Previously, the term ''mammal-like reptile'' had been used, and pelycosaur was considered an order, but this is ...
species found in South African deposits, ''
Elliotsmithia longiceps'', and the
biarmosuchia
Biarmosuchians are an extinct clade of non-mammalian synapsids from the Permian. They are the most basal group of the therapsids. All of them were moderately-sized, lightly-built carnivores, intermediate in form between basal sphenacodont " pelyc ...
n ''
Hipposaurus boonstrai'' are likewise found, including a variety of
basal gorgonopsid
Gorgonopsia (from the Greek Gorgon, a mythological beast, and 'aspect') is an extinct clade of sabre-toothed therapsids from the Middle to Upper Permian roughly 265 to 252 million years ago. They are characterised by a long and narrow skull, ...
,
anomodont
Anomodontia is an extinct group of non-mammalian therapsids from the Permian and Triassic periods. By far the most speciose group are the dicynodonts, a clade of beaked, tusked herbivores.Chinsamy-Turan, A. (2011) ''Forerunners of Mammals: Ra ...
, and
therocephalia
Therocephalia is an extinct suborder of eutheriodont therapsids (mammals and their close relatives) from the Permian and Triassic. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of thei ...
n species. The
dicynodont
Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typic ...
''
Diictodon feliceps'' first appeared in this biozone and remained ubiquitous until the
Permian-Triassic boundary. Other
dicynodont
Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typic ...
species found include ''
Robertia broomiana'' and ''
Pristerodon brachyops''. Finally, fossils of
temnospondyl amphibians such as ''
Rhinesuchus tenuceps'', remains of the fish ''Namaichthys digitata'', invertebrate fossils of
molluscs, invertebrate trackways and burrows, vertebrate
footprints of
therapsid
Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more ...
s, and a variety of plant fossils, namely of ''
Glossopteris'', ''
Dadoxylon'', and ''Schizoneura'', have been recovered.
Correlation
Many
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
n species that are found in the ''
Tapinochephalus'' Assemblage Zone have been found in formations in different countries which correlate in age. As
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
n fossils are only known from Middle
Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleo ...
(
Guadalupian
The Guadalupian is the second and middle series/ epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and Texas, and dates between 272.95 � ...
) deposits,
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
ns are good biostratigraphic markers for this period.
Dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephal ...
n fossils, along with other therapsid species found in the ''Tapinocephalus'' Assemblage Zone, have been recovered from the
Rio do Rasto Formation
The Rio do Rasto Formation is a Late Permian sedimentary geological formation in the South Region of Brazil. The official name is Rio do Rasto, although in some publications it appears as ''Rio do Rastro''.
Geography
It is found mainly in the ...
from the
Paraná Basin in
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
and from the
Madumabisa Mudstone in
Zambia
Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most central point. Its neighbours are t ...
.
See also
*
List of synapsids
References
{{Reflist
South African assemblage zones
Permian South Africa
Guadalupian