Trilobite Hypostome

[Bev]

So I have been playing Caleb's trilobite game and reading on trilobite hypostomes.

So, were trilobites like ticks? Latch onto something and suck the blood?

So, they were blood sucking sea cockroaches?

That seems to be the reason for hypostomes.

[Wendell Ricketts]

No, in a word. Though hypostome is the name given to the structure near the mouth of some parasites like ticks and mites, the structure of the same name in trilobites is not related to blood-sucking.

There's a decent description of hypostome structure and morphology on Sam Gon's site (http://www.trilobites.info/hypoterms.htm) and, at the risk of blowing my own horn, I recommend the Back to the Past Museum Guide to Trilobites by Enrico Bonino and Carlo Kier (translated by yours truly). It's hard to find, but it's got a great discussion of the purpose and function of the hypostome.

Richard Fortey’s paper is also helpful (http://tinyurl.com/ksr3jzl), as is Hegna’s “The Function of Forks” (http://www.academia.edu/213012/The_function_of_forks_Isotelus-type_hypostomes_and_trilobite_feeding).

Hope this is helpful.

W.

[Bev]

Thanks a lot for all of the great references!

[Wendell Ricketts]

P.S. Academia.edu makes you jump through too many hoops to get to the Hegna download, so I'm just going to attach it here.

W.

Hegna - The function of forks Isotelus-type hypostomes and trilobite feeding.pdf

[Wendell Ricketts]

Oops. Found this, too. http://www.trilobita.de/english/feeding.htm, which is interesting.

I'll stop now!

W.

[Auspex]

Sea Nettles are bad enough, let's not even think about Sea Ticks!

[John K]

have you found any Bev? I found this north of you ( around Zumbrota, I think ) in the Decorah Shale:

[FossilDAWG]

The "hypostome" refers to one of the mouthparts present in all chelicerate arthropods, but it (and the other mouthparts, such as chelicerae) are adapted to different food sources in different groups of chelicerates.

Here's an analogous example. Insects have mandibulate mouthparts, including mandibles (duh!), maxillae, labium, labrum, hypopharynx, and clypeus. In grasshoppers, mandibles are used to chew up leaves, the clypeus+labrum+hypopharynx function like our cheeks to keep the food confined so it doesn't fall out while the mandibles are chewing, and the maxillae and labium have finger-like palps that manipulate the food and have the taste sensillae on the tip. In blood-sucking insects such as mosquitoes, all the same elements are present, but rolled into a tube and stretched out to form a long slender "straw" that can be pushed into the skin to reach the blood. So in grasshoppers the mandibles are big jaw-like structures for chewing (oriented sideways instead of top-and-bottom like our jaws), and in mosquitoes the mandibles are long, slender, rolled together, and are used like a straw instead of chewing.

Similarly trilobites and ticks both have a hypostome, but the function differs.

Don

[Bev]

Thanks Don!