In the late '90s, a teenage surfer found a bizarre and frightening fossil embedded in limestone on an Australian beach. It was a massive skull with huge fangs and enormous eye sockets. The fossil ended up gathering dust in a museum office for more than half a decade before an expert named Erich Fitzgerald began studying it.
While some whales have teeth, others don't need them. A blue whale, for instance, takes a massive gulp of seawater and then forces it out through its huge baleen, trapping microscopic zooplankton called krill. The method works well — after all, blue whales are the biggest animals to have ever existed, so they must be doing something right.
Scientists divide modern whales into two groups: those with teeth, like orcas and right whales (Odontoceti), and those with baleen (Mysticeti). Evolutionary biologists once assumed that the two groups split up when the Mysticeti developed baleen. But Fitzgerald's examination of the fossil, which he called Janjucetus hunderi, proved that assumption wrong. That's because while J. hunderi clearly belongs to the Mysticeti subgroup, it doesn't have baleen at all. Twenty-five million years ago, this 10-foot-long (3 meters) early Mysticete scoured the seas for prey to chomp on with its big, sharp teeth [source: Fitzgerald].