The Cambrian Period is the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period 485.4 mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of lagerstätte sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biology surpasses that of some later periods.
Joseph John Sepkoski Jr. was a University of Chicago paleontologist. Sepkoski studied the fossil record and the diversity of life on Earth. Sepkoski and David Raup contributed to the knowledge of extinction events. They suggested that the extinction of dinosaurs 66 mya was part of a cycle of mass extinctions that may have occurred every 26 million years.
In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 149.2 ±0.7 Ma and 145.0 ± 4 Ma. It is preceded by the Kimmeridgian and followed by the Berriasian.
In geology, a sequence is a stratigraphic unit which is bounded by an unconformity at the top and at the bottom.
The Daptocephalus Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. This biozone has outcrops located in the upper Teekloof Formation west of 24°E, the majority of the Balfour Formation east of 24°E, and the Normandien Formation in the north. It has numerous localities which are spread out from Colesberg in the Northern Cape, Graaff-Reniet to Mthatha in the Eastern Cape, and from Bloemfontein to Harrismith in the Free State. The Daptocephalus Assemblage Zone is one of eight biozones found in the Beaufort Group and is considered Late Permian (Lopingian) in age. Its contact with the overlying Lystrosaurus Assemblage Zone marks the Permian-Triassic boundary.
Steven M. Stanley is an American paleontologist and evolutionary biologist at the University of Hawaii at Manoa. He is best known for his empirical research documenting the evolutionary process of punctuated equilibrium in the fossil record.
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 major geological group that forms part of the greater Karoo Supergroup. It represents the first fully terrestrial geological deposits of the Karoo Basin. Outcrops of the Abrahamskraal Formation are found from the small town Middelpos in its westernmost localities, then around Sutherland, the Moordenaarskaroo north of Laingsburg, Williston, Fraserburg, Leeu-Gamka, Loxton, and Victoria West in the Western Cape and Northern Cape. In the Eastern Cape outcrops are known from Rietbron, north of Klipplaat and Grahamstown, and also southwest of East London.
The Sonyea Group is a geologic group in the northern part of the Appalachian Basin. It preserves fossils dating back to the Devonian period.
The Windrow Formation is a geologic formation in Minnesota named after Windrow Bluff on Fort McCoy, Monroe County, Wisconsin. It preserves fossils dating back to the Cretaceous period.
Charles Richard Marshall is an Australian paleobiologist and the director of the University of California Museum of Paleontology, where he is also a professor in the department of Integrative Biology at the University of California, Berkeley.
Marine flooding surfaces are a fundamental concept in sequence stratigraphy, where they form the limiting surfaces of parasequences.
A parasequence is a fundamental concept of sequence stratigraphy. Parasequences are not directly related to sequences.
In geology, range offset is the time difference between the last fossil occurrence of a taxon and the actual disappearance of this taxon. Range offset can be used as a measure of biostratigraphic precision and determines among others how much information about extinctions can be derived from fossil occurrences.
In geology, a subaerial unconformity is a surface that displays signs of erosion by processes that commonly occur on the surface. These processes generating the subaerial unconformity can include wind degradation, pedogenesis, dissolution processes such as karstification as well as fluvial processes such as fluvial erosion, bypass and river rejuvenation.
In sequence stratigraphy, a sub discipline of geology, type 1 sequences and type 2 sequences are special sequences that are defined by having distinct types of sequence boundaries. In modern literature, the distinction in type 1 sequences and type 2 sequences was abandoned.
Susan M. Kidwell is an American paleontologist and geologist at the University of Chicago. Her research has focused on the relationships between fossil concentrations and sequence stratigraphy, experimental taphonomy, and the implications of the very recent fossil record for understanding modern ecological changes.
Stratigraphic paleobiology is a branch of geology that is closely related to paleobiology, sequence stratigraphy and sedimentology. Stratigraphic paleobiology studies how the fossil record is altered by sedimentological processes and how this affects biostratigraphy and paleobiological interpretations of the fossil record.
Bridget S. Wade is a British micropalaeontologist who is a professor at the University College London. Her research considers Cenozoic climate change, which she investigates by studying preserved planktonic foraminifera. Wade was a guest on the 2020 Royal Institution Christmas Lectures.
Nora Noffke is an American geologist who is a professor in the Department of Ocean and Earth Sciences, Old Dominion University in Norfolk, Virginia, USA. Noffke's research focuses on the sedimentology of biofilm forming sedimentary structures in modern aquatic environments, where clastic deposits dominate. Such structures occur in the fossil record as well. Her studies are interdisciplinary combining sedimentology with microbiology, geochemistry, and mineralogy.
Shuhai Xiao is a Chinese-American paleontologist and professor of geobiology at Virginia Tech, Blacksburg, Virginia, U.S.A.
