Day of the Hypostome

Recently I was out in the field with members of our research group, studying the Lexington Limestone in Kentucky. It was one of those rare days in January where the sun was shining and temperatures were at a remarkable 12oC (~55oF)! Well we couldn't let a day like that past so we shook off the cobwebs and went out rid ourselves of some cabin fever.

It was at our first stop near the Rt 127/355 Junction in Kentucky, that one of the undergraduate students brought this slab over to me.

The obvious feature that stands out of course is the light brown 1/2 ring shape outlining the cephalon (head) of an Isotelus trilobite. Isotelus parts are pretty common in the Ordovician of the Cincinnati Arch, sort of the local weed organism which shows up everywhere.We marveled for a moment at the size of the beastie, Isotelus is known to be quite large (largest species is Isotelus rex at ~70cm long - see Palaeocast interview with Dr. Rudkin or the Original Paper) and I was about to hand it back when the real interesting part of the specimen popped out at me, part of the hypostome was present in situ.

The hypostome is the hard mouthpart of a trilobite believed to be used in feeding. It is located on the underside or ventral side of the trilobite. I have a wonderful GIF generated of one of my committee members demonstrating how these hypotstomes may have been used to scoop up worms, but he holds the fate of my future graduation partially in his hands so I will have to refrain from sharing!

Now finding a hypostome is not uncommon by any means, I had found one just a few minutes earlier that was in even better condition. (See my tweet highlighting another hypostome)

The interesting thing is to see the hypostome in situ with all of the cephalon (minus the margin) removed. 

Anyways I thought it was a cool little specimen and I will be certainly adding it to my future teaching collection. Please keep checking here for more posts on interesting fossils/strata we've found and for thoughts on equally interesting papers!