Scientists have discovered the remains of a mysterious, car-sized shark, which swam the coastlines of the Atlantic and Pacific oceans around 20 million years ago. The newly discovered species is a relative of the super-predator megalodon (pictured above), and an ancient ancestor of today’s great white sharks – but there’s a 45-million-year gap in the fossil record before this new species appeared, leaving a lot of unanswered questions about how the shark evolved, and how long it survived. “The fact that such a large … shark with such a wide…