Sepkoski 1 closely studied the genericlevel ordovician. Terminal ordovician carbon isotope stratigraphy and. Mass extinctions in earth history student worksheet published april 2016 page 3 of 4 elaborate, part 1. Unlike many smaller extinction events, however, the longterm. The late ordovician mass extinction request pdf researchgate. The fossil record reveals that these rates fluctuate around a generally low level, but peak at certain points in earths history, indicating mass extinction events. Climate change and the selective signature of the late. One of the past five major extinction events in the history of the earth is the ordovician silurian extinction event. We recognize that the role of a grb in mediating the extinction is at this time only a credible working hypothesis but one worthy of further consideration. Pdf the terminal ordovician was marked by one of five great mass extinction events of the phanero zoic 445. The ordoviciansilurian mass extinction was the second largest mass extinction that took place on earth. The ordovician mass extinction internet 1996 world. Speculated causes of the ordovician extinction glaciation and sealevel lowering hypothesis the ordovician mass extinction has been theorized by paleontologists to be the result of a single event. The graph shows estimated rates of extinction plotted over geologic time.
Rasmussen b a department of earth sciences, durham university, durham dh1 3le, uk b natural history museum of denmark, university of copenhagen, oster voldgade 57, dk50 copenhagen k, denmark. Please submit completed manuscripts via email as a single pdf file by 31 may 20 to. The last event is dated in the interval of, lasting from the middle ordovician to early silurian, thus including the extinction period. Spatial variation in late ordovician glacioeustatic sealevel. The ordoviciansilurian mass extinction michael levenson. Late ordovician mass extinction ordovician silurian youtube.
The big five ordovician silurian extinction 439 million years ago, late devonian extinction 364 million years ago permiantriassic extinction 251 million years ago end triassic extinction, 199 million to 214 million years ago cretaceoustertiary extinction, about 65 million years ago the sixth mass extinction. These keywords were added by machine and not by the authors. In the midst of a biodiversity boom, the ordovician period ended with a mass extinction of almost all life. Near the end of the late ordovician, in the first of five mass extinctions in the phanerozoic, about 85% of marine species died. It is regarded as one of the most widespread, leading to the extinction of approximately 85% of species of marine. Mass extinctions in earth history student worksheet. Evolutionary and biogeographical shifts in response to the. Read the information about this extinction formally known as the cretaceouspaleogene or sometimes the cretaceoustertiary extinction.
This extinction is thought to have started once homo sapiens started dispersing outward from africa on the land bridges, hunting and gathering was. The ordovician period was terminated by an interval of mass extinction. Peter m sheehan department of geology, milwaukee public museum, milwaukee, wisconsin 53233. Dec 21, 2004 analysis of the laurentian data indicates that the recovery from the late ordovician mass extinction occurred within 5 myr in laurentia fig. Mass extinction of the marine biota at the ordoviciansilurian. Late ordovician mass extinction ordovician silurian. Understanding the evolutionary role of mass extinctions requires detailed knowledge of postextinction recoveries. Ordovician mass extinction may have been triggered by. What happened during the ordovician extinction event. In contrast, the mass extinction may have fundamentally changed evolutionary dynamics in the surviving groups. The extinctions include birds, mammals, reptiles, and amphibians. The late ordovician mass extinction hirnantian age, approximately 445 million years ago. Abrupt globalocean anoxia during the late ordovician.
Although no fossils of land animals are known from the ordovician, burrows and trackways from the late ordovician of pennsylvania have been interpreted as produced by animals similar to millipedes. The late ordovician mass extinction approximately 440 million years ago may be at least partly the result of a grb. It has more recently, however, been shown that the silurian was no quieter. Did a gammaray burst initiate the late ordovician mass. The last event is dated in the interval of 455 to 430 million years ago, lasting from the middle ordovician to early silurian. May 18, 2017 geologists from tohoku university, japan, amherst college and washington university in saint louis, the united states, say they may have found the cause of the end ordovician mass extinction, the. Rapid recovery from the late ordovician mass extinction. In fact, the ordoviciansilurian extinction was the second worst mass extinction in the planets history. The ordoviciansilurian boundary interval witnessed one of the major glaciation and the second largest biotic crisis in the phanerozoic, i. Whole abstract volume final volcanism, impacts and mass.
Move the slider down to cretaceous extinction and click on the link. The agnatha, the jawless fishes, were the first animals with true bony skeletons. This extinction, cited as the second most devastating extinction to marine communities in earth history, caused the disappearance of one third of all brachiopod and bryozoan families, as well as numerous groups of conodonts, trilobites, and graptolites. Dec 24, 2014 the terminal ordovician was marked by one of five great mass extinction events of the phanerozoic 445. Did a gammaray burst initiate the ordovician mass extinction.
Berry, department of earth and planetary science, 301 mccone hall, university of california, berkeley, california 94720 usa. About 25% of all families did not make it into the silurian. Ordovician period information and facts national geographic. Gondwana, particularly africa, straddled the south pole and became extensively glaciated and metazoans were severely affected. There are some contests in which its definitely better to finish in second place instead of first. Cambrian ordovician silurian devonian carboniferous permian triassic jurassic cretaceous paleogene neogene quaternary 500 450 400 350 300 250 200 150 100 50 0 future. Due to severe depletion of the ozone layer, intense solar ultraviolet radiation is expected to result fiom a nearby grb, and some of the patterns of extinction and survivorship at this time may be attributable to elevated. This event is sometimes referred to as ordovician extinction or endordovician extinction. Scientists at nasa and the university of kansas say that a mass extinction could have been triggered by a star explosion called a gammaray burst nasa, 2005. In fact, the hirnantian also known as the end ordovician and the ordovician silurian mass extinction event represents the second largest such event in geologic history. Request pdf the late ordovician mass extinction near the end of the late ordovician, in the first of five mass extinctions in the phanerozoic, about 85% of. Five mass extinctions characterize the phanerozoic, the end ordovician, late devonian, end permian, end triassic and end cretaceous. These first steps toward life on land were cut short by the freezing conditions that gripped the planet toward the end of the ordovician.
The ordovician period began with a major extinction called the cambrianordovician extinction event, about 485. Marine carbonate rocks deposited at the time preserve rec ords of a global disturbance to the carbon cycle rep. However, they do not have any direct evidence that a gammaray burst caused the ordovician silurian mass extinction event. Summary of the late ordovician mass extinction running through the possible causes and some of the consequences on marine organisms. The late ordovician mass extinction was an interval of high extinction with inferred low ecological selectivity, resulting in little change in community structure after the event. Mass extinctions in earth history student worksheet published april 2016 page 2 of 4 6gather data. It lasted for about 42 million years and ended with the ordoviciansilurian extinction events, about 443. The first pulse was at the beginning of the glaciation, when sealevel decline drained epicontinental seaways, produced a harsh climate in low and midlatitudes, and initiated active, deep. This extinction event took place during the hirnantian age of ordovician period and the subsequent rhuddanian age of the silurian period. Paleoclimate records indicate global cooling during. In the latter part of the hirnantian, temperatures rose, the. Cooling likely resulted in the establishment of ice sheets on polar gondwana in the katian age or even.
A volcanic trigger for the late ordovician mass extinction. The immense amount of extinction during this period of plants and mammals has constituted is as a mass extinction to many scientists. Each is named for the geologic time it corresponds to. Late ordovician glaciation initiated by early land plant. The late ordovician mass extinction lome, one of the five largest phanerozoic biodiversity depletions, occurred in two pulses associated with the expansion and contraction of ice sheets on gondwana during the hirnantian age. They remove large numbers of species, genera and families, and in varying degrees destroy both marine and terrestrial ecosystems and reset the planets evolutionary agenda jablonski, 1991. Ordovicianearly silurian detected using uranium isotopes of marine. Despite the tremendous expansion of life during the ordovician period there was a devastating mass extinction of organisms at the end of the ordovician. There were extensive reef complexes in the tropics. Vocabulary taconic orogeny caledonian orogeny acadian orogeny antler orogeny paleozoic fauna vascular plant mass extinction 23.
In that extinction sepkoski 1 noted, generic diversity dropped to. Flourishing spongebased ecosystems after the endordovician. Mass extinction of the marine biota at the ordovician. The early part of the hirnantian was characterized by cold temperatures, major glaciation, and a severe drop in sea level. Among the various causes for late ordovician mass extinction harper et al. This mass extinction, the second largest ever, took place about 440 million years ago and wiped out about twothirds of all species.
Species affected the ordovician extinction occurred at the end of the ordovician period, about 440450 million years ago. The second phase of the great ordovician mass extinction is associated with the disappearance of many fossil groups. This event greatly affected marine communities, which caused the disappearance of one third of all brachiopod and bryozoan families, furthermore numerous groups of conodonts, trilobites, and graptolites. This extinction interval ranks second in severity to the one that occurred at the boundary between the permian and triassic periods in terms of the percentage of marine families affected, and it was almost twice as severe as the extinction event that occurred at the end of. The lome stands out among major mass extinctions in being unambiguously linked to climate change. Rapid recovery from the late ordovician mass extinction ncbi. Ordovician devonian permian triassic cretaceous anthropocene. A gamma ray burst may have caused the ordovician extinction, suggests brian thomas and colleagues at the university of kansas. During the ordovician life expanded in diversity tremendously. The ordovician silurian extinction occurred during the hirnantian stage of the ordovician period and the subsequent rhuddanian stage of the silurian period. Home understanding extinction mass extinctions endordovician extinction the extinction at the end of the ordovician period is the oldest of the big five. There have been five mass extinction events in earths history. The ordoviciansilurian extinction occurred during the hirnantian stage of the ordovician period and the subsequent rhuddanian stage of the silurian period.
Mass extinction of late ordovician marine fauna closely coincided with southern hemisphere glaciation. The original text files should be in word mac files are o. This extinction interval ranks second in severity to the one that. Other extinction events paleontologists and geologists have identified four other major extinction events. Mar 15, 20 summary of the late ordovician mass extinction running through the possible causes and some of the consequences on marine organisms. This resulted in the second largest mass extinction of all. The ordoviciansilurian extinction events, when combined, are the secondlargest of the five major extinction events in earths history in terms of percentage of genera that became extinct.
The late ordovician mass extinction lome, 445 ma has long posed a conundrum because it is the only major mass extinction thought to have been driven by climate cooling although causes of the. The terminal ordovician was marked by one of five great mass extinction events of the phanerozoic 445. Ordovician silurian extinction, global extinction event occurring during the hirnantian age 445. Animals had not yet conquered land at this time so the extinction was confined to life in the seas.
Ordovician silurian extinction evolutionary radiation. Ordoviciansilurian extinction, global extinction event occurring during the hirnantian age 445. A special feature of grb in terms of terrestrial effects is a. Around 443 million years ago, at the end of the ordovician period, a major mass extinction occurred. Just because it came in second, however, dont imagine that it wasnt that serious.
Drag the slider to the ordovician extinction, 440 mya. About 60% of animal genera became extinct, making this the second most deadly mass extinction of the phanerozoic. However, the ordovician mass extinction is also seen as the most mysterious because its the oldest and thus the hardest for us to see uc berkeley, 2015. Significant events first vertebrates it was in the ordovician that the first animals with backbones arose. Abstract near the end of the late ordovician, in the. During the first, global sea level dropped nearly 100 m during a marked marine drop in sea level, and steep temperature gradients were established between the poles and the equator.
In fact, species exhibit far greater diversity in the ordovician than in the explosive preceding period. By the end of the ordovician, most of the worlds land masses were combined into the supercontinent gondwana, which. Spatial variation in late ordovician glacioeustatic sea. At least five times in the history of life, the earth experienced mass extinctions that eliminated a large percentage of the biota. There were two distinct extinctions roughly a million years apart. Many possible causes have been documented, and grb may also have contributed. The cause was a brief glacial interval that produced two pulses of extinction. Adjusting for sample size had a significant affect on the laurentian diversity patterns. The early ordovician was thought to be quite warm, at least in the tropics. The tectonic orogeny was the result of a collision of. Effects of mass extinction and recovery dynamics on longterm evolutionary trends. A millipedelike organism is inferred because the burrows occur in discrete size classes, are bilaterally symmetrical, and were backfilled by the. An extinction event is a widespread and rapid decrease in the diversity of organisms.
Pdf mass extinction of the marine biota at the ordoviciansilurian. Causes and effects flett lecture theatre, the natural history museum nhm, london, 2729 march 20 thank you for registering for this conference. The end ordovician extinction comprises two pulses of extinction corresponding to the start and end of the late ordovician glaciation. Mass extinction the ordovician period ended with a mass extinction. Ordovician period 490443 mya life responds quickly following the cambrian extinction. Mass extinction late ordovician marine benthic community glaciation event iapetus ocean. Extinction events have modulated the history of life on our planet. The programme has been organized to cover as many aspects of the major geological extinction events and their hypothesized causes as time allows. The sequence stratigraphic architecture of shallow marine deposits informs estimates of glacioeustatic sealevel change at sites both proximal and distal to the reconstructed ordovician ice sheets and contemporaneous changes in ice volume. Analysis of the laurentian data indicates that the recovery from the late ordovician mass extinction occurred within 5 myr in laurentia fig. That dramatic radiation was truncated abruptly in the late ordovician by one of the two or three most severe mass extinctions among marine organisms to occur within the phaneroic. Cambrian ordovician silurian devonian carboniferous permian triassic jurassic cretaceous cenozoic a mass extinction is a sharp spike in the rate of extinction of species caused by a catastrophic event or rapid environmental change.
The hirnantian is the final internationally recognized stage of the ordovician period of the paleozoic era. The ordovician period was started by an extinction called the cambrian ordovician extinction which lasted about 44. Approximately 85% of marine seadwelling species died. Ultimately the ordovician ended in a brief 300500 ky, but severe, ice age. There have been 520 major mass extinctions in the last 540 million years. Cascading trend of early paleozoic marine radiations. The rapid onset of the continental glaciation on gondwana determined by its position in the south pole area. The dates given are recent radiometric dates and vary slightly from those found in other sources. The first of these began about 443 million years ago. The late ordovician mass extinction lome was the first of the big five phanerozoic mass extinctions, and it eliminated an estimated 61% of marine genera globally 1.