Dinosaur paleontology of the Hell Creek Formation
Got back yesterday from six days out in eastern Montana, at Makoshika State Park. I was there on one of my four MSSE classes this summer, and I learned a lot. As many of you know, I'm trained as a structural geologist, not a sedimentologist. Though I use a lot of sedimentology (and fossils) in my Historical Geology course, there is much I have left to learn. Some of those gaps got filled in this week during "Dino Camp," though. Plus we had a lot of non-geologic fun!
The Hell Creek Formation is well exposed in Makoshika, as well as the overlying Fort Union Formation. The Hell Creek is latest Cretaceous, while the Fort Union is earliest Paleocene. The boundary formerly known as "K/T" is therefore between the two, and it records the changing of the eras: from Mesozoic to Cenozoic. I say "formerly known as K/T," since Tertiary is an archaic term that has been replaced (sort of) with Paleogene. The Paleocene is the first epoch in the Paleogene period. The sedimentologically-defined boundary between the two formations is the lowermost "significant" coal layer. We found this coal, the so-called "Z Coal," and you'd think that would be the K/Pg boundary, but it ain't that simple. True, there are dinosaurs below and no dinosaurs above, and it's also true that the Z Coal has been shown (rather shoddily, by the description we got) to have an iridium anomaly at its base. But there aren't any dinosaur fossils at all for 3 meters below the Z Coal, so the dinosaurs could have gone extinct well before the Z Coal was deposited (and before the iridium-rich clay layer was deposited). And of course, there's nothing in the deposition of a layer of coal that indicates it should be contemporaneous with a mass extinction -- it's just coal. Furthermore, the coal is lake coal, and the lake wasn't necessarily regionally extensive. It's a funny way of defining a critical geochronologic boundary: by the lowermost layer of lake coal in an area -- a criterion which could vary temporally from one place to another. Tricky business!
Anyhow, we prospected for dinosaur fossils. The course had two instructors, Jim Schmitt and Frankie Jackson. Frankie is a paleontologist, and she had a permit for collecting fossils on behalf of the Museum of the Rockies here in Bozeman. We found a lot of vertebrae, some five or six inches across. Plus, we found a bunch of leg bones, some rib fragments, and one of our team actually found the top of the frill on the back of a Triceratops skull! It was all pretty impressive.
In the evenings, we discussed scientific papers about field technique, the Hell Creek Formation, taphonomy, and the extinction of the dinosaurs. All our meals were cooked for us by Frankie's cool husband Bob, and so it was really ideal: Go out and learn all day, come back to camp to a hot meal, a cold beer, and a discussion of big picture ideas. My fellow teachers and I also played a lot of horseshoes and frisbee. To top it all off, when we got back to Bozeman yesterday, a group of us rented Jurassic Park and watched it over pizza and ale.
Next up: tomorrow I begin my Wildlife Ecology of Yellowstone course. Ought to be a similar high-octane experiential blast! More at the end of the week...
The Hell Creek Formation is well exposed in Makoshika, as well as the overlying Fort Union Formation. The Hell Creek is latest Cretaceous, while the Fort Union is earliest Paleocene. The boundary formerly known as "K/T" is therefore between the two, and it records the changing of the eras: from Mesozoic to Cenozoic. I say "formerly known as K/T," since Tertiary is an archaic term that has been replaced (sort of) with Paleogene. The Paleocene is the first epoch in the Paleogene period. The sedimentologically-defined boundary between the two formations is the lowermost "significant" coal layer. We found this coal, the so-called "Z Coal," and you'd think that would be the K/Pg boundary, but it ain't that simple. True, there are dinosaurs below and no dinosaurs above, and it's also true that the Z Coal has been shown (rather shoddily, by the description we got) to have an iridium anomaly at its base. But there aren't any dinosaur fossils at all for 3 meters below the Z Coal, so the dinosaurs could have gone extinct well before the Z Coal was deposited (and before the iridium-rich clay layer was deposited). And of course, there's nothing in the deposition of a layer of coal that indicates it should be contemporaneous with a mass extinction -- it's just coal. Furthermore, the coal is lake coal, and the lake wasn't necessarily regionally extensive. It's a funny way of defining a critical geochronologic boundary: by the lowermost layer of lake coal in an area -- a criterion which could vary temporally from one place to another. Tricky business!
Anyhow, we prospected for dinosaur fossils. The course had two instructors, Jim Schmitt and Frankie Jackson. Frankie is a paleontologist, and she had a permit for collecting fossils on behalf of the Museum of the Rockies here in Bozeman. We found a lot of vertebrae, some five or six inches across. Plus, we found a bunch of leg bones, some rib fragments, and one of our team actually found the top of the frill on the back of a Triceratops skull! It was all pretty impressive.
In the evenings, we discussed scientific papers about field technique, the Hell Creek Formation, taphonomy, and the extinction of the dinosaurs. All our meals were cooked for us by Frankie's cool husband Bob, and so it was really ideal: Go out and learn all day, come back to camp to a hot meal, a cold beer, and a discussion of big picture ideas. My fellow teachers and I also played a lot of horseshoes and frisbee. To top it all off, when we got back to Bozeman yesterday, a group of us rented Jurassic Park and watched it over pizza and ale.
Next up: tomorrow I begin my Wildlife Ecology of Yellowstone course. Ought to be a similar high-octane experiential blast! More at the end of the week...
Labels: dinosaurs, fossils, montana, msse, yellowstone
0 Comments:
Post a Comment
<< Home