| System (period) | Series | Stage (age) | Lower boundary, Ma | |
|---|---|---|---|---|
| Triassic | Lower | Induan | 251.902±0.024 | |
| Permian | Lopingian | Changhsingian |  254.14±0.07
| |
| Wuchiapingian | 259.51±0.21
| |||
| Guadalupian | Capitanian | 264.28±0.16
| ||
| Wordian | 266.9±0.4
| |||
| Roadian | 273.01±0.14
| |||
| Cisuralian | Kungurian | 283.5±0.6 | ||
| Artinskian | 290.1±0.26
| |||
| Sakmarian | 293.52±0.17
| |||
| Asselian | 298.9±0.15
| |||
| Carb. | Pen. | Upper | Gzhelian | older |
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] | ||||
The Changhsingian is an upper stage of the Lopingian series, the Permian system and the whole Paleozoic erathem, corresponding to the Changhsingian age of the Lopingian epoch of the Permian period of the Paleozoic era. It lasted from approximately 254.14 Ma to around 251.902 Ma (million years ago). It is preceded by the Wuchiapingian age of the Lopingian and is followed by the Induan age of the Early Triassic. At the Changhsingian-Induan boundary, the deadliest mass extinction in Earth's history occured. The last rostroconchs, trilobites, eurypterids, seymouriamorphs, dvinosaurids, pareiasaurs, geikiid dicynodonts, gorgonopsians and many other animal groups are known from this stage.
Definition[]
The GSSP of the Changhsingian stage was ratified in 2005. The lower boundary is fixed 88 cm above the base of the Changxing Limestone at the Meishan D Section, Zhejiang Province, China, and related to the first appearance of the conodont species Clarkina wangi.[2]
Changhsingian life[]
Various brachiopods (Marginalosia, Terrakea, Spiriferella, Tomiopsis), bivalves (Guizhoupecten, Permoperna, Acanthopecten, Limipecten) and gastropods (Retispira, Euphemites, Cylindritopsis, Protostylus) continued to live on the Panthalassa ocean floor; ammonites (Changhsingoceras, Sutchanites, Xenodiscus, Huananoceras) and pseudorthocerids (Lopingoceras, Neocycloceras) hunted in water column. The last trilobites, Pseudophillipsia and Acropyge, are known from this stage. Ostracods like Thaumatomma, Parahollinella, Acratinella, Bairdia and Fabalicypris lived in coastal waters. Another genus, Polytylites, was widespread in previous ages of the Carboniferous and Permian, but did not survive the Permian-Triassic extinction. Woodwardopterus, the last known eurypterid, has been discovered in Baralaba Coal Measures Formation in Queensland, Australia. Among aquatic chordates, conodonts (Neogondolella, Hindeodus, Clarkina) were still abundant. Eugeneodontiforms (Helicampodus, Sinohelicoprion) hunted animals with strong shells and carapaces.
The land fauna of this age is less well known, since sedimentation was poor in the continental conditions of Pangea. Life concentrated near rivers and lakes. Various insects including scorpionflies (Prochoristella), beetles (Taldycupes, Palademosyne, Permosyne), permithonids (Permithone, Permopsychops), hemipterans (Permocicada, Beaufortiscus, Stenotegmocicada, Megoniella) and miomopterans (Palaeomantis) lived on the river delta in what is now Kwazulu-Natal, South Africa.
Dipnoan fishes like Gnathorhiza waited out droughts by burying themselves in the sand and breathing atmospheric air. This strategy has allowed them to survive since the Devonian period. Scanilepiform (Toyemia), discordichthyid (Mutovinia, Geryonichthys), eurynotoidiform (Isadia) ans saurichthyiform (Saurichthys) bony fishes as well as chondrichthyans (Wodnika) inhabited rivers and lakes. Temnospondyls also lived near water. Rhinesuchid (Rhinesuchus), lydekkerinid (Lydekkerina) and dvinosaurid (Dvinosaurus) temnospondyls are known from various areas of Pangea. Chroniosuchian tetrapods like Chroniosuchus, Bystrowiana and Uralerpeton were probably ambush predators, like modern crocodiles. Thick skin allowed them to spend more time out of water. Seymouriamorph amphibians like Karpinskiosaurus, Kotlassia and Microphon were also well adapted to life on land. Reptiles, due to their dense skin scales, have perfectly adapted to a dry and hot climate. At this time, quite numerous archosauromorphs, such as Archosaurus, already lived. From such animals crocodiles, dinosaurs and pterosaurs evolved later. Some reptiles, such as Tangasaurus, have already adapted to life in the seas. Changhsingian is the last age in which a variety of parareptiles lived. Millerettids (Milleretta, Millerosaurus), owenettids (Owenetta) and procolophonids (Spondylolestes) resembled lizards, while pareiasaurs (Obirkovia, Elginia, Scutosaurus) were medium-sized to large herbivores covered in tough armor.
Oudenodon skull
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Therapsids spread throughout the continent. Dicynodonts were the most numerous herbivores. Changhsingian genera include Geikia, Gordonia, Daptocephalus, Oudenodon and probably the most widespread, Lystrosaurus, whose fossils of this age are known from South Africa and China. With the help of their fangs, dicynodonts dug up the roots of plants, and their strong beaks allowed them to bite through strong stems and branches. Members of the Geikiidae family did not survive the subsequent extinction, and it remains a mystery why several other species managed to survive. Saber-toothed gorgonopsians (Cyonosaurus, Aelurognathus, Aelurosaurus, Lycaenops) were the main land predators. Eutheriodonts, the most advanced group of therapsids, have reached large numbers. Many of them were predators who hunted small animals. Therocephalians of this age include Notaelurodon, Ictidochampsa, Moschorhinus, Theriognathus, Moschowhaitsia and Megawhaitsia. Cynodonts, the ancestors of mammals, were primarily small animals. Procynosuchus, a procynosuchid cynodont, was found in Western Cape, South Africa.
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "GSSP Table - Paleozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=77.