Trilobite

Remains of creatures that lived long ago are sometimes preserved in stone and called fossils. Technically speaking, any preserved remains are called fossils, even if it is bone, hair, shells, etc. But, most of the fossils which are readily available to the amateur collector (and affordably priced) are stone-based remains of one sort or another.

Of the "Big Three" first items in my collection of stones, crystals, rocks, and fossils, the above fossil of a trilobite (pronounced: /ˈtraɪləˌbaɪt, ˈtrɪ-, -loʊ-/) is the third specimen. I've already shared the arrowhead and black meteorite. All three of these pieces, acquired in the late-1970s and 1980s, were given to me as gifts. The trilobite was given to me by my brother, who remembered that I was fascinated by photos of trilobites as a child and always wanted one. I think they are cute! LOL! He bought this particular specimen in the US state of Arizona at the Petrified Forest National Park.

^{• PHOTO BY ME •}

This fossil that I have is actually the exoskeleton of a trilobite. The soft tissues of the animal decayed before the exoskeleton became trapped in the rock. Please see one of my recent posts for an explanation of what an exoskeleton is. Isn't it wonderful how little tidbits in one post can help provide a clear picture of something in another post...?!?!? 😁

The trilobites were a group of many genera and species within the arthropod phylum. Although they somewhat resemble Wood Lice (a.k.a.: pillbugs, or rolypoly bugs), the two are only distantly related. Trilobites were marine creatures, living in the oceans and seas of the ancient world, and more related to modern crustaceans than anything else. The image at right is an artist's conception of how one species of trilobite (Triarthrus eatoni) might have looked, based on scientific evidence.

Trilobites got their names because of the prefix tri-, meaning "three," and "lobes," as their bodies are divided into three lobes. In the animation at left by me, there are the left- and right-pleural lobes (1) and (2), and the axial lobe (3) in the middle.

Based on fossil evidence, the trilobites lived during the Paleozoic Era, especially during the Cambrian through Permian periods of that Era. If it had not been for the Permian Mass Extinction event (q.v.), we might still have these little critters swimming in our oceans today.

It is thought that some of the trilobite species may have swum and eaten plankton, but many of the species likely stayed on, or near, the bottom of the seas and scavenged for food there. Because of their relatively small size, various species developed unique characteristics, such as the "trident" like horn of the fascinating Walliserops trifurcatus species. Scientists are not certain if this appendage was a sensory organ, a defense mechanism, or something to attract a mate.

Trilobites appear to have first appeared in what is now Siberia, and spread to other parts of the globe as they diversified into further species. They are generally found worldwide, but with high concentrations in North America, the British Isles, Western Europe, and Morocco. These fossil records support the idea of paleocontinents in the developmental history of the Earth.

Lastly, here is a photo of the "Big Three" items that began my collection of rocks, crystals, minerals, and fossils — the trilobite, the arrowhead, and the black meteorite.