The Cretaceous-Paleogene (K-Pg) extinction was huge elimination of some 80% of the fauna and flora around 66 ma. The meteor effect was hellishness. Meteor wide is almost 15 km and depth is 12 km. It was an of the five big extinctions.
Map showing positions and coastlines of Cretaceous landmasses
phys.org
1820: Georges Cuvier realized that significant changes to Earth's animals and plant life occurred between the Mesozoic and the Cenozoic eras.
1831: Mantell declared the Mesozoic era to be the Age of Reptiles.
1842: Sir Richard Owen proposed that the major reptile groups of the Mesozoic were driven extinct as the oxygen contents of Earth's Atmosphere rose to levels better suited for birds and mammals.
1854: Charles Darwin published On the Origin of Species. He regarded the extinction of most taxonomic groups as occurring gradually through the piecemeal loss of member species. However, he considered the extinction of the ammonites at the end of the Mesozoic to have been "wonderfully sudden".
1882 : Othniel Charles Marsh interpreted the extinction of the dinosaurs as a gradual decline over the course of the Cretaceous.
1898: Arthur Smith Woodward also advocated that the dinosaurs gradually declined into extinction late in the Mesozoic.
1917: Franz Nopcsa suggested that dinosaurs may have developed overactive pituitary glands that led them to become pathologically gigantic in an evolutionary parallel to acromegaly in modern humans.
1925: Paleobotanist George Wieland hypothesized that Tyrannosaurus rex survived on a diet of eggs
L. Müller proposed that volcanic eruptions drove the dinosaurs extinct.
1928: H. T. Marshall suggested that bombardment from cosmic or ultraviolet radiation caused the extinction of the dinosaurs.
1946: Edwin Harris Colbert and others proposed that the dinosaurs went extinct when Earth's climate became too hot and dry to support them.
1949: M. Wilfarth argued that dinosaurs were marine animals and were driven extinct by decreasing sea levels during the Late Cretaceous, which dried out their habitats.
1950: Petroleos Mexicanos, also known as PEMEX, discovered an unusual subsurface circular structure in the Yucatan Peninsula of Mexico.
1960: PEMEX began drilling into the unusual ring-like structure under the Yucatan and extracting rock cores in search of oil.
1967 : J. M. Cys argued that dinosaurs went extinct because they were unable to hibernate during the winter, leaving them doomed by Earth's changing climate.
1970: PEMEX continued looking for oil deposits associated with a large circular structure in the Yucatan Peninsula.
1971: D. A. Russel and Tucker proposed that a nearby supernova emitted a burst of electromagnetic radiations and cosmic rays that killed off the dinosaurs.
1973: Harold Urey argued that comet impacts may have caused mass extinctions in the past and may have been responsible for demarcating the periods of the geologic time scale.
1974: Jan Smit began studying the extinction of foraminifera at the K–T boundary in Caravaca, Spain. He observed that some of these extinctions must have been rapid.
1977 : Alvarez and others[who?] published their research on the magnetic reversals of the Cretaceous-Tertiary boundary interval recorded in the rocks at Gubbio, Italy. They proposed that these rocks be regarded as the standard to which other rocks thought to be of this age are compared.
Spring: Jan Smit sent 100 rock samples from the K–T boundary at Caravaca to a laboratory in Delft for compositional analysis. The results uncovered high levels of metals like antimony, chromium, cobalt, nickel, and selenium. These unusual findings led Smit to suspect that the mass extinction at the end of the Cretaceous may have had an extraterrestrial cause.
Robert T. Bakker argued that Earth's terrain flattened out during the Late Cretaceous, reducing the area of the dinosaurs' preferred habitats and helping to drive them to extinction.
1978: Cloudsley-Thompson suggested that if dinosaurs were warm-blooded, increasing temperatures could have caused them to overheat and driven them extinct.
1980: Alvarez and others reported spikes in the level of platinum group metals like iridium at the Cretaceous-Tertiary boundary in Italy, Denmark, and New Zealand. They interpreted this sudden introduction of rare-earth metals as evidence for an asteroid impact, to which they attributed the mass extinction at the end of the Cretaceous Period.
1990: The Chicxulub Crater in Mexico's Yucatan Peninsula was rediscovered.
1991: Hildebrand and Boynton declared the Chicxulub Crater to be the result of the impact that triggered the mass extinction at the end of the Cretaceous. Hildebrand and others estimated the diameter of the Chicxulub Crater at 170 kilometers.
1992: Sigurdsson and others concluded that global mean temperatures dropped 2–3 degrees Celsius across the Cretaceous-Tertiary boundary.
1993: Lecuyer and others concluded that mean temperatures in some areas dropped as much as 8 degrees celsius following the Cretaceous.
1994: Smith and others concluded that the Late Cretaceous drop in sea levels constituted the most severe marine regression of the entire Mesozoic Era.
1998: Lopez-Martinez and others noted the presence of sauropod and ornithopod tracks near the K–T boundary in the Tremp Formation of northeastern Spain. The presence of tracks so close to the Cretaceous-Tertiary suggests that the dinosaur died out rapidly rather than gradually.
Sullivan argued that dinosaur biodiversity experienced a marked decline over the last ten million years of the Cretaceous Period. Stromberg and others reported that fossil pollen from the Hell Creek Formation provided evidence for a gradual shift in the region's flora "from more open to more closed and moist habitats".
1999: Norris and others concluded that the extinction of many foraminiferas at the end of the Cretaceous was abrupt rather than gradual. (More info : Wikipedia)
1831: Mantell declared the Mesozoic era to be the Age of Reptiles.
1842: Sir Richard Owen proposed that the major reptile groups of the Mesozoic were driven extinct as the oxygen contents of Earth's Atmosphere rose to levels better suited for birds and mammals.
1854: Charles Darwin published On the Origin of Species. He regarded the extinction of most taxonomic groups as occurring gradually through the piecemeal loss of member species. However, he considered the extinction of the ammonites at the end of the Mesozoic to have been "wonderfully sudden".
1882 : Othniel Charles Marsh interpreted the extinction of the dinosaurs as a gradual decline over the course of the Cretaceous.
1898: Arthur Smith Woodward also advocated that the dinosaurs gradually declined into extinction late in the Mesozoic.
Compilation of 105 terrestrial K-Pg boundary sections
1917: Franz Nopcsa suggested that dinosaurs may have developed overactive pituitary glands that led them to become pathologically gigantic in an evolutionary parallel to acromegaly in modern humans.
1925: Paleobotanist George Wieland hypothesized that Tyrannosaurus rex survived on a diet of eggs
L. Müller proposed that volcanic eruptions drove the dinosaurs extinct.
1928: H. T. Marshall suggested that bombardment from cosmic or ultraviolet radiation caused the extinction of the dinosaurs.
1946: Edwin Harris Colbert and others proposed that the dinosaurs went extinct when Earth's climate became too hot and dry to support them.
1949: M. Wilfarth argued that dinosaurs were marine animals and were driven extinct by decreasing sea levels during the Late Cretaceous, which dried out their habitats.
1950: Petroleos Mexicanos, also known as PEMEX, discovered an unusual subsurface circular structure in the Yucatan Peninsula of Mexico.
1960: PEMEX began drilling into the unusual ring-like structure under the Yucatan and extracting rock cores in search of oil.
1967 : J. M. Cys argued that dinosaurs went extinct because they were unable to hibernate during the winter, leaving them doomed by Earth's changing climate.
1970: PEMEX continued looking for oil deposits associated with a large circular structure in the Yucatan Peninsula.
1971: D. A. Russel and Tucker proposed that a nearby supernova emitted a burst of electromagnetic radiations and cosmic rays that killed off the dinosaurs.
1973: Harold Urey argued that comet impacts may have caused mass extinctions in the past and may have been responsible for demarcating the periods of the geologic time scale.
1974: Jan Smit began studying the extinction of foraminifera at the K–T boundary in Caravaca, Spain. He observed that some of these extinctions must have been rapid.
1977 : Alvarez and others[who?] published their research on the magnetic reversals of the Cretaceous-Tertiary boundary interval recorded in the rocks at Gubbio, Italy. They proposed that these rocks be regarded as the standard to which other rocks thought to be of this age are compared.
Spring: Jan Smit sent 100 rock samples from the K–T boundary at Caravaca to a laboratory in Delft for compositional analysis. The results uncovered high levels of metals like antimony, chromium, cobalt, nickel, and selenium. These unusual findings led Smit to suspect that the mass extinction at the end of the Cretaceous may have had an extraterrestrial cause.
Robert T. Bakker argued that Earth's terrain flattened out during the Late Cretaceous, reducing the area of the dinosaurs' preferred habitats and helping to drive them to extinction.
1978: Cloudsley-Thompson suggested that if dinosaurs were warm-blooded, increasing temperatures could have caused them to overheat and driven them extinct.
1980: Alvarez and others reported spikes in the level of platinum group metals like iridium at the Cretaceous-Tertiary boundary in Italy, Denmark, and New Zealand. They interpreted this sudden introduction of rare-earth metals as evidence for an asteroid impact, to which they attributed the mass extinction at the end of the Cretaceous Period.
1990: The Chicxulub Crater in Mexico's Yucatan Peninsula was rediscovered.
1991: Hildebrand and Boynton declared the Chicxulub Crater to be the result of the impact that triggered the mass extinction at the end of the Cretaceous. Hildebrand and others estimated the diameter of the Chicxulub Crater at 170 kilometers.
1992: Sigurdsson and others concluded that global mean temperatures dropped 2–3 degrees Celsius across the Cretaceous-Tertiary boundary.
1993: Lecuyer and others concluded that mean temperatures in some areas dropped as much as 8 degrees celsius following the Cretaceous.
1994: Smith and others concluded that the Late Cretaceous drop in sea levels constituted the most severe marine regression of the entire Mesozoic Era.
1998: Lopez-Martinez and others noted the presence of sauropod and ornithopod tracks near the K–T boundary in the Tremp Formation of northeastern Spain. The presence of tracks so close to the Cretaceous-Tertiary suggests that the dinosaur died out rapidly rather than gradually.
Sullivan argued that dinosaur biodiversity experienced a marked decline over the last ten million years of the Cretaceous Period. Stromberg and others reported that fossil pollen from the Hell Creek Formation provided evidence for a gradual shift in the region's flora "from more open to more closed and moist habitats".
1999: Norris and others concluded that the extinction of many foraminiferas at the end of the Cretaceous was abrupt rather than gradual. (More info : Wikipedia)
We have a lot of information about this extinction. I have no idea how many articles have included this topic but we can visualize how this extinction occurred over time.
Stay Safe
0 Comments:
Yorum Gönder