A new study suggests that being a little shrimpy might come in handy when the going gets tough. A mass extinction called the Hangenberg event, which took place some 359 million years ago, led to a reduction in vertebrate size for around 40 million years after. The research, published recently in Science, adds support to the so-called Lilliput Effect, which suggests that mass extinctions cause marked shrinkage in the animal population.
To study how fish fared after this extinction, the University of Pennsylvania’s Lauren Sallen (with Andrew K. Galimberti, now a graduate student at the University of Maine) studied 1,120 fish fossils dating back 419 million to 323 million years ago. She found that the ancient fish had been increasing in size over time — which is to be expected — but that body size plummeted after 97 percent of species were wiped out.
“Some large species hung on, but most eventually died out,” Sallan said. Before the extinction, some fish had grown to be as big as school buses. But in the unstable ecosystem of a post-mass-extinction ocean, only small fish — ones that could reproduce quickly and survive on less food — could thrive.
That means an ocean full of enormous sea monsters gave way to an ocean full of sardinelike critters.
