A jawless fish 12-17-20

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Fishing Season

On the Rocks – the Woodstock Times

Apr. 1, 1999

Updated by Robert and Johanna Titus


Wave your arm around in a wide arc. It is passing through air, but it is passing through history as well. Wherever you are, so many things have gone before. Your arm is passing through space that was once occupied by the core of a mountain range, the depths of a sea, dense jungles, a sandy beach and many other things. In the future the space your arm passed through will similarly have many more, equally different manifestations. The seas will return and also mountains will rise here again. Time passes, and times change, and the Earth evolves. You just have to wait long enough, and these things happen.

It’s the same with plants and animals. Wave your arm and it passes through space once occupied by dinosaurs and trilobites and saber-tooth tigers. We share space with these creatures; we just don’t share their time. Each creature, humble or proud, gets its moment in time, passes this way and then fades away, only to be replaced at another moment by another creature.

All this is, of course, an introduction to this week’s topic. It’s, once again, fishing season. If you enjoy fishing in the Catskills, maybe you would like to know about some of the forms that were here long ago. Wave your arm through the air; it is passing through space once occupied by some of those primitive fish. The Catskill region has yielded a very large number of fossil fish from a critical time in fish evolution. Let’s talk about one of them: Its name is Cephalaspis. When we say primitive we are not kidding. It belongs to a group of fish among the oldest and least evolved of all the fossil fish. These are referred to as the jawless fish. As we are sure that you can guess, jawless fish lacked a lower jaw. They had very simple mouths but no teeth. In a fish-eat-fish world the lack of jaws and teeth is a real disadvantage but that’s the way it was back when they first appeared. The jawless fish were rather un-endowed in other categories as well. They had only the most rudimentary of fins, just one set located towards the front. Modern fish have two sets of paired fins and others located bottom and top. Thanks to all these fins modern fish have a lot of control over their swimming. But poor Cephalaspis couldn’t have been a very effective swimmer.

So how did Cephalaspis get along if it couldn’t swim well and had little or no bite? It was certainly not a predator. More likely these creatures were scavengers. They would have swum the ponds and sluggish rivers of the old Catskill delta complex in search of food that was already dead.

Cephalaspis was not without any skills. These fish had large and sturdy head shields. Those were broad bones that covered the top of their skulls, giving the animal some pretty good defenses. Within these head shields are the sockets of eyes and these fish must have had reasonably good vision. There was also a third opening called a pineal opening which was also light sensitive although its exact function is unknown. Then there are strange areas of the head shield which are interpreted as “fields” of sensory functions. Again, the exact functions are unknown.

Cephalaspis is a very rare fossil in our area. Some specimens have been reported from local marine sandstones, probably between the villages of Veteran and Unionville. It is not uncommon elsewhere, nor is it unimportant. Bones are far more common in Europe and in Canada. There, the skulls are often very well preserved, and we have learned quite a bit about early fish from the studies of these. But you will not catch one of these this spring. Cephalaspis has been extinct for more than 300 million years.

Contact the authors at randjtitus@prodigy.net. Join their facebookpage “The Catskill Geologist.” 

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