Fossils

I need to clear something up. Geology is the study of rocks, not fossils. The study of fossils is paleontology. People are always confused by that. It's understandable I suppose, because pretty much all geologists really like fossils, and the rocks they are found in are really quite interesting to paleontologists. Quite a lot of overlap, very confusing.

Acrocanthosaurus at the beach.

Over thanksgiving break we dragged the kids around to see and collect some fossils. Our first stop was Dinosaur Valley State Park in Glen Rose Texas. Here you can see some of the best preserved dinosaur tracks in the world sitting on the riverbed of the Paluxy River. It's a cool place. About 113 million years ago the area was the edge of a shallow sea. The beach wasn't like we normally think of a beach, it was gooey calcareous mud. One day, a herd of Pleorocoelus (like a brontosaurus but with a shorter neck and tail) walked down the beach. They were followed by a couple of Acrocanthosaurus (like a t-rex but a bit smaller) who were presumably trying to catch up and eat them. This probably happened a lot, but the tracks from this particular day were covered and preserved. When the Paluxy river wore away limey shales over this old beach, the tracks were exposed. They've been extensively studied and a large section of them has been cut out of the rock and placed on display at the American Museum of Natural History in New York. This was really a good thing to do as the action of the river naturally erodes the tracks and something that is 113 million years old can degrade within one human lifetime. I don't know if they are still on display there but I'd love it if someone would stop by and let me know. Luckily there are several tracks that are still visible and in great shape at the park. We had a great time hiking around and seeing the tracks and exploring and talking about dinosaurs.

Fantastic ammonite cast.

Our second fossil stop of the trip was to Lake Benbrook outside Fort Worth Texas. This is the one time when the drought in Texas is working to our advantage. The lake level is really really low so much of the shore that you can walk on and explore now is usually under water. This was easily the best fossil hunting day I've ever had. We found dozens of partial ammonites, tons of clams of various sorts, quite a few snail shells and one small sand dollar. All of the kids could easily find fossils and we ended up hauling quite a lot of them back to the truck. The recommended place to fossil hunt isn't actually on the shore where we were (because it's usually under water) but in the rock cut for the dam spillway. This is probably a great spot to find fossils and we did find a few, including a couple of incredible ammonite casts. If we hadn't already found such easy and abundant fossils on the lake bed we would have loved it, but we were spoiled. These fossils are from a younger rock, only 70-85 million years old, and were formed by a shallow sea. We had a good time discussing the fact that ammonites, which are like a squid in a shell, not a snail, are extinct but snails and clams and sand dollars are not. Extinctions happen, but life itself lives on. So far.
 We had a great trip, found some of the best fossils of our lives and got to see real dinosaur tracks. Can't beat that.