The Trouble with Trilobites

 

 

DON’T STEP THERE!

Yikes! Look down where you stand. Walk with care. Trilobites are everywhere! Well, at least here in Kentucky.

Pick up a rock in your stream. Chances are that it contains trilobites. Or maybe just parts of them. That’s the problem. We want it all now. A big, beautiful, completely whole trilobite in three parts. The head (cephalon), thorax, and tail (pygidium).

But hunters must be disciplined and patient. That is also true for finders of fossils. Look for a sign. Look long. Hard. Sit in one place and look for tiny structures in rock. Maybe there you will find a trilobite.

I have searched for trilobites for most of my adult life. They are my golden fleece. I just wasn’t trained in paleontology. I don’t know how to look for their parts. I confuse their ridged tailpieces with the mollusk-like shells of the brachiopods. I see their hard trilobite mouth pieces (hypostomes) as smooth, broken clam shells. I look at gems, but see only pebbles.

WALK IN THE OCEAN

The ocean right here in Kentucky. Well, at one time it was here. And you might as well swim in it again! All the rocks below you once did. They swirled and settled into bottom detritus, complete with casts of those life forms once swimming or sitting above it. And what would you see if you could swim back in time? Trilobites, of course. And much more!

Let us take a look at the Devonian Geologic Period in which fossil reefs were growing 380 million years ago. Right here at the Falls of the Ohio at Louisville, Kentucky. The only natural navigational barrier on the Ohio River. The Devonian is called the “Age of Fishes,” but those were giant armored fish. Not many of their fossils at the Falls. If you find one, it might be part of Dunkleosteus, a 30-foot-long placoderm with monstrous jaws. But you will find fossils of all sorts of other diverse life forms: corals, moss animals (bryozoans), brachiopods, sea lilies (crinoids), sea buds (blastoids), giant sea scorpions (eurypterids), and other cool life forms. But they would soon be faced with one of the great extinction events in geologic history. There have been at least five such periods. Some argue that a sixth is occurring right now!

But go ahead. Snorkel lazily above in your mind and peer down below at the reef. Just like you do when you are swimming at Key Largo. And what can you see here but not there? Trilobites, of course. If you can find them.

SWIM IN THE SEAS

Trilobites flourished in Earth’s oceans for more than 250 million years. From the early Cambrian Geologic Period through the Ordovician, Silurian, Devonian,

Mississippian, Pennsylvanian, and Permian Periods. Kentucky was under water during this entire time, collecting rocks and fossils upon which you can live and look.

So trilobites are us; so to speak. We tread their waters. Swim their seas. Thanks to Continental Drift and the Cincinnati Arch, rock and strata of all of these Geologic Periods are exposed at the surface in Kentucky. That’s what you see in the creek bottoms and road cuts around here. So as you swim casually in your mind over these warm, ancient seas, you swim with the trilobites. Frustratingly fun to identify, these fossils. Some with long legs, some with long horns. Some very flat, some curled up like a bedroll. If you can find them!

And don’t forget to do your back exercises before you hunt for them. Those muscles are needed. As is a hand lens. You are not dreaming anymore. Be careful on road cuts. Don’t trespass on land. Hunt with a friend. Take a bag or a bucket. Enjoy the moment. The more you look and let go of your petulant self, the more life you will see in the rock. And tiny creatures will form up from the otherwise errant lines in the rock. They are not cracks in the stone. They are lives that once lived, like you, in this sea. Now concentrate your focus. Raise your hand and hammer. There is more to be found at your feet!

HORSESHOE CRABS

No, horseshoe crabs are not trilobites. And not crabs either! They are living fossils, however, their record in rock going back into the earliest stones exposed in Kentucky. They are probably related to those mysterious, extinct sea scorpions. Do you remember picking up a horseshoe crab by the tail on a Florida beach?

 

There are those out there who can help you find trilobites here. They know where, within our frozen seas, these trilobites hide. Check out the Kentucky Paleontological Society. Attend one of their meetings. Go on a field trip.

Swim again in our ancient seas!

 

045a7678Trilobite tracks!

(Photographs by Cheryl Van Stockum)