Last Friday we took a look at a nicely preserved fossil from the Pennsylvanian. Since this is Answer Monday, I will drop the cagey act and tell you now that it is clearly a plant. Here you can see the fossil with scale.
Regarding identification, while the UIowa fossil curator places this specimen definitely in the Equisetum genus, its species is not known. I figured many of you would identify this fossil as some kind of a horsetail, since extant members of the family closely preserve this body plan. However, I hoped I would lead you to believe that I had access to a GIANT horsetail. During the Pennsylvanian period there were species in the genus Equisetum that were both very large and quite common, with trunks around half a meter thick and heights of up to twenty meters. Did I manage to trick you? This week’s specimen, as you can now see, is more in the use-as-a-paperweight category than use-as-as-coffee-table category.
Regardless, it does give me a good opportunity to talk about these plants, for which I have a fondness. Horsetails are the first organisms that made the concept of deep time real to me as a small child. Of course I had learned about dinosaurs and other exciting prehistoric animals when I was growing up, but I think it’s easy for children to mix those creatures up with fantastic beasts and make-believe concepts. I mean, what self-respecting person hasn’t pretended to be a T. rex at some point or another?
When I was in fourth grade I had a teacher who often took us on nature hikes. I remember very vividly looking at a stand of horsetails with her, and asking why they were not like other plants. Take a good look at some Equisetum the next time you see them, they really aren’t put together like modern plants. The way light reflects off them is different due to their density of silicates, and their proportions are a little odd. Mrs. Durham told me that it was because these plants are different from the other plants we saw that day. That the horsetails were in some ways ancient, even though they were alive today. That millions and millions of years ago I could have seen plants very much like these horsetails, but that many of the other plants we had seen on our walk would not yet exist. She told me that horsetails have been around since before a flower ever bloomed on Earth.
How astonishing I found this concept! A world without flowers! A world before flowers! Really, I think this group of extant ancient plants is quite a good teaching tool. Horsetails are pretty common, they’re easy to identify, and they give you a really good intro to talk about the world before flowers. Nice and concrete. A handy way to blow a kid’s mind—or maybe even an adult’s.
The winner this week? Well, nobody said Equisetum, but GrizzlyD, John Macdonell, and Dan Coleman all said either horsetail or Annularia, so they can share the laurels (Laurus nobilis). Congratulations, and thanks for playing! If you have a fossil you want to share, send your pictures to me at schoerning at ncse.com.