Permian–Triassic
extinction event:
The
Permian–Triassic extinction event, colloquially known as the Great Dying,was an
extinction event that occurred around the boundary between the Permian and
Triassic geologic periods, and with them the Paleozoic and Mesozoic eras. It is
Earth's most severe known extinction event, with the extinction of 57% of
biological families, 62% of genera, 81% of marine species, and 70% of
terrestrial vertebrate species. It is also the greatest known mass extinction
of insects. It is the greatest of the "Big Five" mass extinctions of
the Phanerozoic. There is evidence for one to three distinct pulses, or phases,
of extinction, with the major pulse of marine extinction occurring in a 60,000-100,000
year interval around 251.902 million years ago (mya) marking the boundary
between the Permian and Triassic periods. There is some controversy regarding
the chronology of the extinctions on land and whether they are synchronous with
the main marine extinction event.
LAND ANIMAL EXTINCTION DURING PERMIAN AGE DESCRIBE WITH 3D PICTURE:
4 LAND ANIMALS NAMED DIMETRODON SCUTOSAUR LYSTRASAURAND INOSTANCERVIA ON THE PERMIAN PLANE WHERE VOLCANIC ERUPTION STARTED IN BACKGROUND ON SIBERIAN TRAPS 4 LAND ANIMALS NAMED DIMETRODON SCUTOSAUR LYSTRASAURAND INOSTANCERVIA ON THE PERMIAN PLANE WHERE VOLCANIC ERUPTION GROW RAPIDLY IN BACKGROUND ON THE SIBERIAN TRAPS 4 LAND ANIMALS NAMED DIMETRODON SCUTOSAUR LYSTRASAURAND INOSTANCERVIA ON THE PERMIAN PLANE WHERE DUE TO RAPID VOLCANIC ERUPTION PERMIAN PLAIN GRADUALLY COVERED WITH DEEP RED SMOKE WHICH CAUSES PANIC TO THE ALL LAND ANIMALS ON PERMIAN PLANE 4 LAND ANIMALS NAMED DIMETRODON SCUTOSAUR LYSTRASAURAND INOSTANCERVIA ON THE PERMIAN PLANE WHERE DUE TO RAPID VOLCANIC ERUPTION THE PERMIAN PLAIN IS COVERED WITH DEEP RED SMOKE ERUPTION FIRE AND RED HOT MAGMA BURST OUT FROM THE EARTH
DUE TO RAPID VOLCANIC ERUPTION THE PERMIAN PLAIN IS COVERED WITH DEEP RED SMOKE ERUPTION FIRE AND RED HOT MAGMA BURST OUT FROM THE EARTH AND DUE TO THIS CATASTROPIC EVENT MOST OF THE LAND ANIMALS DIED.
DUE TO HUGE HEAT OF PERMIAN PLAIN AND ERUPTED LAVA THE DEAD BODIES LAND ANIMALS GRADUALLY EVAPORATED DUE TO HUGE HEAT OF PERMIAN PLAIN AND ERUPTED LAVA THE DEAD BODIES LAND ANIMALS GRADUALLY EVAPORATED AND ULTIMATELY DISAPPEAR AND CONSUMED BY RED HOT LAVA.
The
scientific consensus is that the main cause of the extinction was the flood
basalt eruptions that created the Siberian Traps, which released sulfur dioxide
and carbon dioxide, resulting in euxinia (oxygen-starved, sulfurous
oceans),[elevated global temperatures and acidified oceans. The level of
atmospheric carbon dioxide rose from around 400 ppm to 2,500 ppm with
approximately 3,900 to 12,000 gigatonnes of carbon being added to the
ocean-atmosphere system during this period.
CAUSES OF PERMIAN MASS EXTINCTION
 |
| CAUSES OF PERMIAN MASS EXTINCTION |
Several
other contributing factors have been proposed, including the emission of carbon
dioxide from the burning of oil and coal deposits ignited by the eruptions;
emissions of methane from the gasification of methane clathrates ;emissions of
methane by novel methanogenic microorganisms nourished by minerals dispersed in
the eruptions; longer and more intense El NiƱo events; and an extraterrestrial
impact that created the Araguainha crater and caused seismic release of methane
and the destruction of the ozone layer with increased exposure to solar
radiation
Dating:
Previously,
it was thought that rock sequences spanning the Permian–Triassic boundary were
too few and too incomplete for scientists to reliably determine their details. However,
it is now possible to date the extinction with millennial precision. U–Pb
zircon dates from five volcanic ash beds from the Global Stratotype Section and
Point for the Permian–Triassic boundary at Meishan, China, establish a
high-resolution age model for the extinction – allowing exploration of the
links between global environmental perturbation, carbon cycle disruption, mass
extinction, and recovery at millennial timescales. The first appearance of the
conodont Hindeodus parvus has been used to delineate the Permian-Triassic
boundary.
The
extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031 million years
ago, a duration of 60 ± 48 thousand years. A large, abrupt global decrease in
Ī“13C, the ratio of the stable isotope carbon-13 to that of carbon-12, coincides
with this extinction, and is sometimes used to identify the Permian–Triassic
boundary and the Permian-Triassic Mass Extinction event (PTME) in rocks that
are unsuitable for radiometric dating. The negative carbon isotope excursion's
magnitude was 4–7% and lasted for approximately 500 kyr,though estimating its
exact value is challenging due to diagenetic alteration of many sedimentary
facies spanning the boundary.
Terrestrial
vertebrates:
The tempo
of the terrestrial vertebrate extinction is disputed. Some evidence from the
Karoo Basin indicates a protracted extinction lasting a million years. Other
evidence from the Karoo deposits suggest it took 50,000 years or less, while a
study of coprolites in the Vyazniki fossil beds in Russia suggests it took only
a few thousand years.Aridification induced by global warming was the chief
culprit behind terrestrial vertebrate extinctions. High herbivore mortality in
turn drove carnivore extinctions.There is evidence that over two thirds
of terrestrial labyrinthodont amphibians, sauropsid ("reptile") and
therapsid ("proto-mammal") taxa became extinct. Large herbivores
suffered the heaviest losses.
4 LAND ANIMALS NAMED DIMETRODON SCUTOSAUR LYSTRASAURAND INOSTANCERVIA ON THE PERMIAN VOLCANIC PLANE
All Permian anapsid reptiles died out except the procolophonids (although testudines have morphologically-anapsid skulls, they are now thought to have separately evolved from diapsid ancestors). Pelycosaurs died out before the end of the Permian. Too few Permian diapsid fossils have been found to support any conclusion about the effect of the Permian extinction on diapsids (the "reptile" group from which lizards, snakes, crocodilians, and dinosaurs (including birds) evolved). Tangasaurids were largely unaffected.The PTME represented the largest extinction of anomodonts in their evolutionary history.
Gorgonopsians INOSTANCERVIA SP APEX PREDATOR SPECIES DURING PERMIAN
Gorgonopsians are conventionally thought to have gone extinct during the PTME, but some tentative evidence suggests they may have survived into the Triassic. Freshwater and euryhaline fishes, having experienced minimal diversity losses before the PTME, were unaffected during the PTME and actually appear to have increased in diversity across the Permian-Triassic boundary. However, faunal turnovers in freshwater fish communities occurred in areas like the Kuznetsk Basin.
DIMETRODON MAMMAL PREDATOR SPECIES
The
groups that survived suffered extremely heavy losses of species, and some
terrestrial vertebrate groups very nearly became extinct at the end of the
Permian. Some of the surviving groups did not persist beyond this period, but
others that barely survived went on to produce diverse and long-lasting
lineages. However, it took 30 million years for the terrestrial vertebrate
fauna to fully recover both numerically and ecologically.
LARGE HERBIVORE SCUTOSAUR SPECIES
It is difficult to estimate extinction and survival rates of land organisms because few terrestrial fossil beds span the Permian–Triassic boundary. The best-known record of vertebrate changes across the Permian–Triassic boundary occurs in the Karoo Supergroup of South Africa, but statistical analyses have so far not produced clear conclusions.
ONLY FEW LYSTROSAURUS SURVIVED THE GREAT DYING
One study of the Karoo Basin found that 69% of
terrestrial vertebrates went extinct over 300,000 years leading up to the
Permian-Triassic boundary, followed by a minor extinction pulse involving four
taxa that survived the previous extinction interval. Another study of the
latest Permian vertebrates in the Karoo Basin found that 54% of them went
extinct due to the PTME.
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