Life in Earth's oceans bounced back far more quickly than thought after world's worst mass extinction
- Fossils including sharks, sea reptiles and squid-like creatures dug up in Idaho reveal a marine ecosystem thriving relatively soon
- Contradicting the long-held notion life was slow to recover from the calamity.
Fossils
including sharks, sea reptiles and squid-like creatures dug up in
Idaho reveal a marine ecosystem thriving relatively soon after Earth's
worst mass extinction, contradicting the long-held notion life was
slow to recover from the calamity.
Scientists
on Wednesday described the surprising fossil discovery showing
creatures flourishing in the aftermath of the worldwide die-off at the
end of the Permian Period about 252 million years ago that erased
roughly 90 percent of species.
Even the
asteroid-induced mass extinction 66 million years ago that doomed the
dinosaurs did not push life to the brink of annihilation like the
Permian one.
An artist's depiction of the
diversified and complex Early Triassic marine ecosystem of southeastern
Idaho, U.S., revealed soon after the Earth's worst mass exinction,
contradicting long-held notion life was slow to recover from calamity.
The
fossils of about 30 different species unearthed in Bear Lake County
near the Idaho city of Paris showed a quick and dynamic rebound in a
marine ecosystem, illustrating the remarkable resiliency of life.
'Our
discovery was totally unexpected,' said paleontologist Arnaud Brayard
of the University of Burgundy-Franche-Comté in France, with a highly
diversified and complex assemblage of animals.
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View of a sampled slab from the Paris Biota showing abundant fish scales and shrimp.
The
ecosystem from this pivotal time included predators such as sharks up
to about 7 feet long (2 meters), marine reptiles and bony fish,
squid-like creatures including some with long conical shells and others
with coiled shells, a scavenging crustacean with large eyes and
strangely thin claws, starfish relatives, sponges and other animals.
The Permian die-off occurred 251.9 million years ago.
The Idaho ecosystem flourished 1.3 million years later, 'quite rapid on a geological scale,' according to Brayard.
The mass extinction's cause is a matter of debate.
But
many scientists attribute it to colossal volcanic eruptions in
northern Siberia that unleashed large amounts of greenhouse and toxic
gases, triggering severe global warming and big fluctuations in oceanic
chemistry including acidification and oxygen deficiency.
The
Idaho ecosystem, in the earliest stages of the Triassic Period that
later produced the first dinosaurs, included some unexpected
creatures.
A graphic detailing how the Early
Triassic was an epoch that recorded major extinctions and geochemical
perturbations. The largest extinction event and the one that affected
the Earth's ecology most profoundly took place 252 million years ago.
There
was a type of sponge previously believed to have gone extinct 200
million years earlier, and a squid-like group previously thought not to
have originated until 50 million years later.
The
researchers found bones from what could be the earliest-known
ichthyosaur, a dolphin-like marine reptile group that prospered for 160
million years, or a direct ancestor.
'The
Early Triassic is a complex and highly disturbed epoch, but certainly
not a devastated one as commonly assumed, and this epoch has not yet
yielded up all its secrets,' Brayard said.
The research was published in the journal Science Advances.
THE FIVE MASS EXTINCTIONS
Five
times, a vast majority of the world's life has been snuffed out in what
have been called mass extinctions, often associated with giant meteor
strikes.
End-Ordovician mass extinction
The
first of the traditional big five extinction events, around 440 million
years ago, was probably the second most severe. Virtually all life was
in the sea at the time and around 85 per cent of these species vanished.
Late Devonian mass extinction
About
375-359 million years ago, major environmental changes caused a
drawn-out extinction event that wiped out major fish groups and stopped
new coral reefs forming for 100 million years.
End-Permian mass extinction (the Great Dying)
The
largest extinction event and the one that affected the Earth's ecology
most profoundly took place 252 million years ago. As much as 97 per cent
of species that leave a fossil record disappeared forever.
End-Triassic mass extinction
Dinosaurs
first appeared in the Early Triassic, but large amphibians and
mammal-like reptiles were the dominant land animals. The rapid mass
extinction that occurred 201 million years ago changed that.
End-Cretaceous mass extinction
An asteroid slammed down on Earth 66 million years ago, and is often blamed for ending the reign of the dinosaurs.
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