Fossil Fish, Pt. II: A History
– So see, he plowed up this giant rock here and it’s got a palm leaf on it. – Oh wow. – So we’re here with Lance Grande, who is the distinguished service curator at the Field Museum, and we are standing in a giant rock quarry in Wyoming – This is a great lake system, called the Green River lake system, which persisted almost 20 million years. – Oh man. – [It’s] one of the longest-lived lake systems that we know of. – Wow. – And we’re in the smallest and shortest-lived of those lakes, Fossil Lake, which probably only existed about a million and a half years. But that’s a long time for any lake, especially when you
consider the Great Lakes in North America. They’re only about 10,000 years old. – Wow, yeah, we got nothing on this lake system. – You have an entire community here that’s locked in stone. We’re out here lifting these slabs and we’re seeing all kinds of things that haven’t seen the light of day for 52 million years. – I think most people—when you tell them that you’re going on a paleo dig— —they assume you’re looking for dinosaurs. Clearly we’re not finding any dinosaurs of the typical kind out here, but we are finding an entire ecosystem, essentially. – Well, and it’s interesting that you bring up dinosaurs, because one of the interesting things about this site is… you know, about 65 million years ago, we had the extinction of most of what we think of as dinosaurs, except for the bird lineage. That was due to a meteorite impact off the coast of Yucatán, which left a 50 mile wide crater there. It extinguished more than 50 percent of all the species on the planet. And what we’re seeing here is how the Earth was recovering after that. – This is the largest or most complete representation
of early Eocene life in the world. – Oh by far. This is an amazing locality. This is probably the most productive fossil locality in North America. – Really?
– We have a lot of different birds coming in, in a sky that’s no longer ruled with pterosaurs. – Right. – You know, we’ve got mammals taking the place of all these terrestrial dinosaurs that existed before. And although they’re very peculiar when you compare them to mammals and some birds today, they’re nevertheless representatives of these modern families. – It is very hot. I’ve noticed this. It didn’t take me very long to realize there’s not a lot of shade around here, and it’s curious to me because we’re standing next to what is obviously and evidently evidence of a palm frond, which indicates that this climate is much different today than it was millions of years ago. – This high mountain desert is a real contrast to the subtropical environment that existed here 52 million years ago. We not only have these palms, that the bulldozer pried up yesterday, there was a crocodile found right over there. It was about 12 feet long. And you have chunks like this, which represent volcanic ash. There were active volcanoes around the lake. Remember, we’re talking about geologic time, so when we look at this quarry here and go all the way up to the top of the highest quarry here, we may be talking about 50,000 years or more. And if you think in ecological time how much can happen in even a hundred years or a thousand years, the fact that we find volcanic eruptions and maybe signs of earthquakes, that is just common and it’s compressed time because we’re
looking at geologic time. – So, in addition to finding random fishes, you’ll find little
schools of mini fishes and that sort of thing, but we’re also finding and discovering behaviors of animals that were previously unknown. – This site is so amazing and there was this flash preservation of things almost. And so I can come out and I can find fishes that are in the process of choking to death on other fishes. Fishes with stomach contents of other animals that they’ve swallowed… I can find leaves with insect chew marks and the insects
that made the chew marks. There’s even a stingray, a rare stingray here, called Asterotrygon. We have a mated pair that are actually clasped together. And then a pregnant female, and then another slab with a female that had just given birth with two young beside it. – A lot of the stuff that we’re finding here too—yes they’re extinct, but they’re not totally unknown or unrecognizable species. – Just the other day there were two 6 foot turtles found
in the quarry next to us. There’s a three-toed horse that comes out of this quarry, which is about 24 inches high at the shoulders as an adult. This place has been mined for fossils for more than 150 years, and there have probably been 3 million fishes excavated in that time. And there’s still a fish that’s only known by one specimen: a pike. In 3 million fishes, only one pike, and what that tells me is there’s so many things here that we haven’t found yet. It’s just this—you know, you need almost an infinite sample size to know what actually existed then. – We have a very pieced-together map of life on Earth as we know it, and by looking at places like this kind of locality, we’re able to find the puzzle pieces that fit into the timeline, essentially. – Well that’s exactly right. The evolutionary pattern’s a network, and we find pieces of it in almost every group. We have the bird that is a missing link between the swifts and the hummingbirds. We have fishes that link different families. We have all kinds of things here that literally answer questions about evolutionary trees that were previously unable to put together. – Do you think we’ll ever exhaust this area? Do you think we’ll ever get to a point where people
think we’ve found everything there is to find here? – No. It would be impossible.