This Dutch Collector Turned His Home Into an Incredible Fossil Museum

Ron Janssen can still recall the spot on the side of the Maas river where he found a few teeth in the mud as a child — now 62, he often returns there when the tide is low, hoping to find something more. Back then, he picked up the teeth, assuming they were from cows or horses in nearby fields. “I later found out they went back 10,000 years — they were from boars and other animals that were alive then,” he says. That find sparked a passion for fossils that the Dutch businessman now indulges with more splashy acquisitions, like his latest, a spectacular ichthyosaur or prehistoric dolphin.

It was Janssen’s grandfather who sparked a curiosity for curios, a man whose attic and barn were stuffed with unfamiliar, exotic-looking ob...