From the rust-brown sediments of long-dried streams that once rumbled through the rugged terrain of Canada’s Ellesmere Island, a team of paleontologists unearthed in 2004 fossils of a 375 million-year-old species of fish that may have nearly crossed an evolutionary Rubicon. Named Tiktaalik roseae, the nowextinct animal has come to represent an intermediate link between fish and amphibians, its ...