Giant fossils challenge “lilliput effect” in animals after greatest mass extinction

February 12th, 2010 - 5:52 pm ICT by ANI  

Washington, Feb 12 (ANI): The discovery of large-sized fossils dating back to only 1 million years after the greatest mass extinction of all time, has called into question the existence of a “Lilliput effect,” the reduction in the size of organisms after the annihilation.

The specimens were found by an international team including a French researcher from the Laboratoire Biogeosciences, working with German, American and Swiss colleagues.

The team’s results have drastically changed paleontologists’ current thinking regarding evolutionary dynamics and the way the biosphere functions in the aftermath of a mass extinction event.

The history of life on Earth has been punctuated by numerous mass extinctions, brief periods during which biodiversity is considerably reduced, followed by phases of re-conquest of the biosphere, corresponding to the diversification of those species that survived.

The most devastating of these, the Permian-Triassic (P-T) mass extinction, which decimated more than 90 percent of the marine species existing at the time, occurred 252.6 million years ago with a violence that is still unequaled today.

In the aftermath of such events, environmental conditions are severely disrupted, like, the oceans become less oxygenated, water becomes poisonous, there is increased competition, and the collapse of food chains.

Until now, it has generally been accepted that certain marine organisms, such as gastropods or bivalves, were affected by a drastic reduction in size in response to major disruptions of this nature, both during and after the event.

It took several million years for such organisms to return to sizes comparable to those that existed prior to the crisis.

This is what scientists call the “Lilliput effect,” in reference to the travels of the fictional character of Gulliver who was shipwrecked on the island of the same name, inhabited by very small Lilliputians.

But, an international team of French, German, American and Swiss paleontologists has recently discovered large gastropod fossils dating from only 1 million years after the P-T mass extinction.
By focusing their efforts on fossil-bearing outcrops in Utah dating from the Early Triassic, which have not yet been studied in detail, they have uncovered some outstanding specimens of gastropods, up to 7 cm, which can be termed as “giants” in comparison to those generally found, normally no bigger than 1 cm.

Complementary studies of these new gastropod fauna also indicate that they are not any smaller than older or present-day fauna.

This discovery therefore refutes the existence of a Lilliput effect on gastropods during the major part of the Early Triassic or, at the very least, suggests that its importance has been overestimated. (ANI)

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