It was definitely the biggest adventure of my life This was the Canadian Arctic. Hundreds of miles away from any settlement. We had a narrow summer window of a few weeks when the weather cooperates just long enough to let us in. If we were lucky, we would reveal a desert landscape with freshly exposed rocks. We traveled thousands of miles to find fossils from one of the great transitions of evolution: The move of vertebrates from water to land. We were experienced fossil hunters. “You gotta go higher, Neil.” But now we’d have to learn to become polar explorers This part of the Arctic has rocks of the right age and the right type to hold evidence of a great transition: When our ancient fish ancestors moved from water onto land. It’s hard to believe when you look at this frozen landscape that once this was a warm, watery world swimming with life. This valley, 375 million years ago, was a giant floodplain. and that floodplain was filled with rivers that swelled their banks and sometimes shrunk but in those conditions formed swamps and streams of all different sizes. And inside those streams was diverse life. And somewhere out there our distant relatives sank into muddy graves which would preserve them for 375 million years. At the end of our stay in 2000 we found a hill loaded with fossils. and over the next four years we dug hoping to find the fossils we were looking for. It was the second week of July in 2004. We’re all working in series in this hole You know, where my head is right next to Farish’s feet and Farish’s feet is next to Steve Gatesian. We’re digging together and Steve says, “Hey guys, what’s this?” Ted and I go running over to see what Steve was referring to and what we saw was this V here. It was covered with rock. and as soon as we saw this V and we saw these teeth under it it became very clear that this little V we’re seeing is the tip of the snout and that this was the snout of a flat-headed fish. Based on other fossils from slightly younger rocks, this feature alone suggested we might have a transitional fish. OK. We get home. We knew we had a flat-headed fish but how much of it did we have? Then about a month and a half goes by. and they start to find the orbits (the eye holes). And then we see the shoulder And then we see the fins. And then we see more and more and more until we see pretty much the entire top side of the body. So you can not only say, “What did this animal look like?’ but we can begin to ask, “You know how did it work?” “How did move about in these 375-million-year-old streams?” The local Inuit people came up with the name Tiktaalik for our fossil. It means large freshwater fish. But although this creature had the scales and fin of a fish, it also had the flat head and rotating neck of a land animal. And when we looked at its fins we realized it had the beginnings of the bone structure that’s shared by all four-limbed vertebrates today. It had versions of an upper arm and forearm, even parts of a wrist. This was a fish from a pivotal moment in evolutionary history. Descendants of fish like Tiktaalik would go on to spawnreptiles, mammals and, eventually, us.