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 date between 272.3 ± 0.5 – 259.8 ± 0.4 Mya. The series saw the rise of the therapsids, a minor extinction event called Olson’s Extinction and a significant mass extinction called the end-Capitanian extinction event.
The Guadalupian was previously known as the Middle Permian.
|Subdivision of the Permian system|
according to the ICS, as of 2017.
The Guadalupian is the second and middle series or epoch of the Permian. Previously called Middle Permian, the name of this epoch is part of a revision of Permian stratigraphy for standard global correlation. The name "Guadalupian" was first proposed in the early 1900s, and approved by the International Subcommission on Permian Stratigraphy in 1996. References to the Middle Permian still exist. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains in New Mexico. The International Chronostratigraphic Chart (v2018/07) provides a numerical age of 272.3 ± 0.5 – 259.8 ± 0.4 Mya.
Therapsids became the dominant land animals in Guadalupian, displacing the pelycosaurs. Therapsids evolved from a group of pelycosaurs called sphenacodonts. Therapsida consists of four major clades: the dinocephalians, the herbivorous anomodonts, the carnivorous biarmosuchians, and the mostly carnivorous theriodonts. After a brief burst of evolutionary diversity, the dinocephalians died out in the later Guadalupian.
This extinction was originally called Olson's Gap because it was thought to be a problem in preservation of fossils. Since the 1990s it has been renamed Olson’s Extinction. This extinction event occurred near the beginning of the epoch and led to an extended period of low diversity when two-thirds of terrestrial vertebrate life was lost worldwide. Global diversity rose dramatically by the end probably the result of disaster taxa filling empty guilds, only to fall again when the end-Guadalupian event caused a diversity drop in the Wuchiapingian.
There is no agreed cause for the Olson's Extinction. Climate change may be a possible cause. Extreme environments were observed from the Permian of Kansas which resulted from a combination of hot climate and acidic waters particularly coincident with Olson’s Extinction. Whether this climate change was a result of Earth's natural processes or exacerbated by another event is unknown.
The first two-thirds of the epoch were the continuation of a temperate and tropical climate. This started to dry out and the coal forming of the previous epoch stopped. The change in climate also provided a new environment for new tetrapod‘s reptiles fish plants and invertebrates.
In the last third the temperature started to drop and many coral reefs died out. If that was not enough, increased volcano activity brought a reduction in oxygen, a greenhouse and mass extinction.
The Roadian stage was between 272.3 ± 0.5 – 268.8 ± 0.5 Mya.
Olson’s Extinction was a worldwide loss of terrestrial vertebrate life that occurred during the Roadian and Wordian.
Fauna did not recover fully from Olson's Extinction before the impact of the Permian-Triassic extinction event. Estimates of recovery time vary, where some authors indicated recovery was prolonged, lasting 30 million years into the Triassic.
Several important events took place during Olson's Extinction, most notably the origin of therapsids, a group that includes the evolutionary ancestors of mammals. Further research on the recently identified primitive therapsid of the Xidagou Formation (Dashankou locality) in China of Roadian age may provide more information on this topic.
The Wordian stage was between 268.8 ± 0.5 – 265.1 ± 0.4 Mya.
The base of the Wordian stage is defined as the place in the stratigraphic record where fossils of conodont species Jinogondolella aserrata first appear. The global reference profile for this stratigraphic boundary is located at Getaway Ledge in the Guadalupe Mountains of Texas.
The top of the Wordian (the base of the Capitanian stage) is defined as the place in the stratigraphic record where the conodont species Jinogondolella postserrata first appears.
The Capitanian stage was between 265.1 ± 0.4 – 259.8 ± 0.4 Mya.
The Guadalupian ended with a deteriorating environment, Greenhouse conditions, and several series of mass-extinctions; both the great dinocephalians, other taxa on land and various invertebrates in the sea. They would be succeeded by new types of mammal-like reptiles.
A significant mass extinction event (the End-Capitanian extinction event) occurred at the end of this epoch, which was associated with anoxia and acidification in the oceans and possibly caused by the volcanic eruptions that produced the Emeishan Traps. This extinction event may be related to the much larger Permian–Triassic extinction event that followed about 10 million years later.
This climatic cooling may have caused the end-Capitanian extinction event among species that lived in warm water, like larger fusulinids (Verbeekninidae), large bivalves (Alatoconchidae) and rugose corals, and Waagenophyllidae.
Subdivisions that are sometimes used are,
Brithopodidae is an extinct family of carnivorous dinocephalian therapsids that are known from the Middle Permian of Russia and Texas.Cynariognathus
Cynariognathus (meaning puppy jaw) is an extinct genus of middle sized carnivorous therocephalian from the Tapinocephalus Assemblage Zone of South Africa. It is sometimes considered a synonym of Pristerognathus.Dinocephalia
Dinocephalia is a clade of large-bodied early therapsids that flourished for a brief time in the Middle Permian between 270 and 260 million years ago (Ma), but became extinct, leaving no descendants. Dinocephalians included herbivorous, carnivorous, and omnivorous forms. Many species had thickened skulls with many knobs and bony projections. Dinocephalian fossils are known from Russia, China, Brazil, South Africa, Zimbabwe, and Tanzania.Eutheriodontia
The Eutheriodontia are a clade of therapsids that includes therocephalians and cynodonts.
The clade was named in 1986 by James Allen Hopson and Herbert Richard Barghusen, the name meaning the "True Theriodontia". Within Hopson's system, the Eutheriodontia are the sister group of the Gorgonopsia within the Theriodontia. A close relationship between therocephalians and cynodonts had been recognized for many years. In 2001 the Eutheriodontia were defined as the least inclusive clade including Mammalia and Bauria.Therocephalians and cynodonts are thought to have diverged in the Middle Permian, and each group independently evolved mammal-like features, including a secondary palate and the loss of a postorbital bar (these features were retained in mammals, which are considered a derived group of cynodonts). Mammalian features that both groups inherited from a common ancestor include the loss of teeth on the palate, the expansion of the epipterygoid bone at the base of the skull (an area called the alisphenoid in mammals), and the narrowing of the skull roof to a narrow sagittal crest running between large temporal openings.Karrowalteria
Karrowalteria is an extinct genus of therocephalian therapsids from the Middle Permian of South Africa. It belongs to the family Scylacosauridae, and resembles the genera Pristerognathus and Scymnosaurus. It is known from a single species, karrowalteria skinneri, named by South African paleontologists A. S. Brink and J. W. Kitching in 1958 to replace the preoccupied walteria which was named in honor of Alex J. Walter Skinner, who found the holotype skull near Laingsburg, Western Cape.Lycosuchidae
Lycosuchidae is an extinct family of therocephalian therapsids from the Middle Permian Beaufort Group of South Africa. It currently contains two monotypic genera, Lycosuchus, represented by L. vanderrieti, which was named by paleontologist Robert Broom in 1903, and Simorhinella, represented by S. baini, which was named by Broom in 1915. Both species are characterized by their large body sizes and short, deep snouts. Two sets of enlarged canine teeth were once regarded as a defining feature of lycosuchids, but recent studies have proposed that the front-most pair are replacements for the ones behind them, which would have eventually fallen out as individuals aged. Lycosuchids are the earliest known therocephalians and are also thought to be the most basal.Lycosuchus
Lycosuchus ("wolf crocodile") is an extinct genus of carnivorous therocephalians which lived in the Middle Permian 265—260 Ma existing for approximately 5 million years. It was a medium-sized predator, reaching 1.2 m (3.8 ft) in length with a skull 23 cm long.
Discovered in South Africa, it was named by paleontologist Robert Broom in 1903 and later assigned by him to Therocephalia.Neodiapsida
Neodiapsida is a clade, or major branch, of the reptilian family tree and includes all diapsids apart from some early primitive types known as the araeoscelidians.
In phylogenetic systematics, they are variously defined as the common ancestor and all its descendants of Younginiforms and "crown diapsids" (the common ancestor of lizards, crocodilians and birds, and all their descendants) [Callaway 1997], or all diapsids that are more closely related to Sauria than to Araeoscelidia (Laurin and Gauthier 2000).
Early or basal Permian neodiaspids were lizard-like, but already include specialised forms for swimming (Claudiosaurus) and gliding (Coelurosauravidae), as well as more conventional lizard-like forms (Youngina etc.). Before the end of the Permian, the neodiapsids give rise to the main branches of the diapsid evolutionary tree, the lepidosaurs and archosaurs.Neotherapsida
The Neotherapsida are a clade of therapsids. The clade includes anomodonts and the more derived theriodonts, which include mammals.Novocynodon
Novocynodon is an extinct genus of thrinaxodontid cynodonts from the Middle Permian of Russia. Fossils have been found in Alexandrovsky District, Orenburg Oblast. The type and only species is Novocynodon kutorgai.Otsheria
Otsheria is an extinct genus of anomodont from the Permian of Russia. Otsheria had a 10 centimetres (3.9 in) long skull.Permian
The Permian is a geologic period and system which spans 47 million years from the end of the Carboniferous period 298.9 million years ago (Mya), to the beginning of the Triassic period 251.902 Mya. It is the last period of the Paleozoic era; the following Triassic period belongs to the Mesozoic era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the region of Perm in Russia.The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs, and archosaurs. The world at the time was dominated by two continents known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, which could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors.
The Permian (along with the Paleozoic) ended with the Permian–Triassic extinction event, the largest mass extinction in Earth's history, in which nearly 96% of marine species and 70% of terrestrial species died out. It would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian–Triassic extinction event was protracted; on land, ecosystems took 30 million years to recover.Pristerognathoides
Pristerognathoides ("Pristerognathus-like one") is an extinct genus of middle sized carnivorous therocephalians from the Tapinocephalus Assemblage Zone of South Africa. It is sometimes considered a synonym of Pristerognathus.Pristerognathus
Pristerognathus is an extinct genus of therocephalian, known from the late Middle Permian (Capitanian) of South Africa. It lends its name to the Pristerognathus Assemblage Zone of the Beaufort Group of South African geological strata. Pristerognathus was a medium-sized therocephalian with a 25 cm (9.8 in) skull and a total length up to 1.5 m (4 ft 11 in).These animals were roughly dog-sized, and are characterized by long, narrow skulls with large canines. They are likely to have lived in woodlands, and preyed on smaller therapsids and millerettids of the time.Pristerognathus was discovered in 1895 by Seeley. Three species are known: P. baini, P. polyodon and P. vanderbyli. There has also been a fourth species P. minor, but this has been reclassified to Pristerognathoides.Sauria
The clade Sauria was traditionally a suborder for lizards which, before 1800, were crocodilians. It has been redefined as the group containing the most recent common ancestor of archosaurs and lepidosaurs and all its descendants; as such it was commonly thought that Sauria is a crowned-base grouping of diapsids. However, recent genomic studies and comprehensive studies in the fossil record suggest that turtles are closely related to archosaurs, not to parareptiles as previously thought. Sauria can be seen as a crowned-group of all modern reptiles (including birds) within the larger total group Sauropsida, which also contains various stem-reptile groups.Theriodont
The theriodonts or Theriodontia ("the ones with beast teeth", referring to more mammal-like teeth) are a major group of therapsids. They can be defined in traditional, Linnaean terms, in which case they are a suborder of synapsids that lived from the Middle Permian to the Middle Cretaceous, or in cladistic terms, in which case they include not only the traditional theriodonts but also their descendants the mammals as well (in the same way that, cladistically speaking, the theropod dinosaurs include the birds as a sub-clade).Ulemica
Ulemica is an extinct genus of venjukoviid therapsids. It was a basal member of the suborder Anomodontia that existed during the Middle Permian in Russia. The type species, U. invisa, was assigned to the genus Venjukovia prior to being placed within its own genus in 1996. This small anomonodont is only known from a partial skull.Venyukoviidae
Venyukoviidae is an extinct family of small herbivorous anomodont therapsids that are known from the Permian of Russia.
(541.0 Mya–2.5 Gya)
|Archean eon (2.5–4 Gya)|
|Hadean eon (4–4.6 Gya)|