I’m so sore today. Took a long hike, 10-12 miles, over some rock formations that tend to break up into boulders. Up and down, boulder to boulder. Hard work. But we got to see some rock formations we haven’t seen before and we continue to make discoveries.
Our last day is tomorrow. We’ve had a relatively short season compared to our six other Arctic expeditions, but we really worked this area hard. We covered 35 square miles on foot and surveyed additional areas when flying in by helicopter. Logged 13 fossil sites, meaning there are enough fossils at these sites to log them, to take geographical information, and to collect fossils to bring back.
We’re finding an awful lot of the same creatures we found before: armored fish and lobe-finned fish, but nothing in the limbed realm. What’s interesting is these same rock formations further to the east produced large numbers of a fish called Psammosteus, but there are none here. This shows ecological differentiation. Maybe we’re too far out into the delta system, too far away from the prime area where that type of fish seemed to have lived.
The common thing we’ve seen across all the various environments and time periods is Bothriolepis, a small (about 12 inches long) heavily armored placoderm fish. It’s presumed that Bothriolepis spent most of its life in freshwater, but was probably able to enter salt water as well. Some hypothesize that they lived most of their lives in saltwater and returned to freshwater to breed, similar to salmon. It had a long pair of spine-like pectoral fins which may have been used to lift its body clear off the bottom, but its heavy armor (that protected against predators) would have made it sink quickly.
So we need to look at that common animal and see if there are patterns, where they are found, the great diversity of them. What does that tell us? This is all part of what we’ve been doing this trip: putting the final touches on the bigger project. Over our seven trips to the Arctic, we’ve systematically surveyed many rock formations through the Late Devonian Period and across a geographic transept.
Everything we find is new because no one has ever reported any of these fish from any of these locations. Some things are expected some are unexpected. The big picture has to wait a little. I’ll be thinking of some preliminary conclusions.
Lots of conclusions will come with time and looking at the big picture.