A recent study by University of Pennsylvania’s Lauren Sallen, assisted by Andrew K. Galimberti, has found that after the Hangenberg event — a mass extinction which took place on the planet around 359 million years ago — vertebrate species such as fish seem to have gotten smaller, reported the New York Times.
The study provides support for the Lilliput Effect theory. This theory, named after the Lilliputians in Jonathan Swift’s Gulliver’s Travels,” notes that, in the wake of mass extinction events, a reduction in the surviving creatures’ size can be expected, as animals are forced to do more with less.
Sallen’s study found that vertebrate species (in her case, fish) remained smaller for 40 million years after the event. The Washington Post quoted Sallen as saying “some large species hung on, but most eventually died out … the end result is an ocean in which most sharks are less than a meter and most fishes and tetrapods are less than 10 centimeters, which is extremely tiny. Yet these are the ancestors of everything that dominates from then on, including humans.”
Some large species hung on, but most eventually died out … the end result is an ocean in which most sharks are less than a meter and most fishes and tetrapods are less than 10 centimeters, which is extremely tiny. Yet these are the ancestors of everything that dominates from then on, including humans.
Before the Hangenberg event occurred, the ocean was full of enormous marine creatures, with some fish having grown as big as school buses. But afterwards — some theories postulate that the Hangenberg effect caused a global ice age, bringing glaciers down even as much as the tropics — their ecosystem was destabilized, and only fish which could survive on less food and reproduce more quickly could survive.
Sallen’s study began while studying fish from the Mississippian period, from 359 to 323 million years ago. She noticed that the fish she was studying were all substantially smaller than their ancestors had been. Having only a small sample to work with, however, she couldn’t say anything for sure, so she studied every known vertebrate species that lived in both the Devonian and Mississippian periods.