Everyone loves a great big shark.

The world’s seas bear a greater abundance of small sharks. I learned this as a young shark fan. Almost every shark book stated that there were more than 350 known shark species, only a handful posing any potential risk to people, and most are small. (The count now exceeds 550 living shark species.) But even with my love of the epaulettes and cookie cutters, the lantersharks and spinners, the draw of the big sharks is hard to ignore. To think, out there, swim fish that stretch more than three times my height and weigh multiple tons. Just as there were hundreds of millions of years ago.

The big sharks were found in northern Australia. Not in the water, but in the rock. Ashtray-shaped bones, vertebral centra, are littered through the 115 million-year-old rocks of the Darwin Formation. The largest of these are nearly five inches in diameter, big bones from sizable sharks.