The Mississipian and Pennsylvian periods which lasted from 365 to 315 and 315 to 290 million years ago are referred to as the Carboniferous, not a Welsh locale .  Life on land was getting interesting, but the trilobites were fading out.  It seems that trilobites did better in eras named after places in Wales.



Superfamily:  Proetoidea
Family:  Phillipsiidae

1.6cm  Missouri


1.2cm diameter  Wolf Mountain Shale; Wise County, Texas

1.4 cm  Staunton Formation; Coal Run, Indiana

 Trilobites were disappearing, but there were a lot of Crinoids.

4cm calyx Harrodsburg Limestone, Montgomery County,  Indiana

3.5cm calyx  (same as above specimen)




The Permian period closed out the Paleozoic and spelled THE END for trilobites.  It lasted from 290 to 245 million years ago.  By the way, it was named for Perm, a city in Russia, not Wales, which obviously was the problem for our segmented friends.



Superfamily:  Proetoidea
Family: Phillipsiidae

8 mm diameter  Pueblo Formation; Camp Colorado Shale, Brown Co, Texas



Trilobites are famous for their eyes.  They were the first organisms to show complex visual structures.  Many trilobites had schizoachroidal eyes, consisting of arrays of calcite lenses.  Pictured above is a mud's eye view of an oncoming Coltraenia oufatenensis, often called "Treveropyge".  They had nearly 360 degrees of vision.  Here are a few more; can you recognize which trilobite each came from?

*answers below

This is a holochroal eye.  It has a corneal covering over the array of lenses.

It is from a Paralejurus.  Some of my other scutellids have similar eyes, but these from the Paralejurus are much larger and easier to photograph.


Almost all trilobites after the Cambrian had the ability to roll up in a ball like a sleeping Chihuahua, probably as a means of defense.  Their cephalons and pygidiums fit tightly together. an ability facilitated by Isopygy, which means their lengths are the same.


Trilobites had to rest sometime.   This is a Rhusophycus pudicum, a resting place or "nest" associated with Flexicalymene trilobites.  This one was found in Kentucky and is covered with a variety of other trilobite parts, brachiopods and crinoid fragments.


This is an extremely small Elrathia kingi.

I found several of these tiny fossils while cleaning up the mud on some specimens I found at the U-Dig Trilobite Quarry near Delta , Utah.  It is mounted on the head of a pin, which can be seen extending beyond the edges of the fossil itself.


I have seen trilobite earrings, but my ears aren't pierced.  My wife understands my trilobite infatuation, but she won't wear bugs on her ears.  For those times when I absolutely have to wear a trilobite, I have found some pins.  If you want to track some down for yourself, check out the links below.

Previously, most of the close-up photographs in this site were taken with either a Minolta X-700 or SRT-101, using a Vivitar 55mm Macro lens, generally using natural sunlight for illumination.   The photographs were scanned and adjusted using PhotoShop to improve display, but absolutely no spines were added.   Although many of my previous photographs looked great in their original prints, there was an obvious loss of quality in the scanning process.  Furthermore, if the picture didn't come out exactly as I intended, I had to wait for another roll of film to see if I could get it right the next time around.  I am now using an Olympus C-765 digital camera with an amazing macro capability.  I can get immediate feedback and can keep shooting until I am reasonably satisfied with the result.  While the camera is capable of 4 megapixels, I am using it at 2 mp and the results still provide a lot more detail than the scanned images that they are replacing. 


Fossil preparation can be fun, if a bit nerve-wracking.  While I can't claim to have prepared most of my specimens, I have done a great deal of preparation on a number of them.  Several, including the Ceratarges type A and Cyphaspis still had a lot of matrix when I bought them.  I liberated them using dental tools, a #11 scalpel and a Dremel Mototool with a series of diamond bits.  While I have really enjoyed watching them emerge from their stony tombs after hundreds of millions of years, I must admit that this can be an anxiety provoking experience, especially when working with small spines, hard matrix and an expensive fossil.  I certainly felt it prudent to buy a Comura rather than trying to prep one myself.  Even when I don't do much to the fossil, its display is often enhanced by some extra work to clean up the matrix.  Many Moroccan trilobites are prepared with rather distinctive grooves in the matrix.  I find them rather distracting and prefer the smoother and higher contrast appearance resulting from taking them down with a grinder and Dremel.  



I hope that you have learned something new about something old.  There are a lot of books on fossils.  The Eyewitness Handbook, FOSSILS has around twenty different kinds depicted with some basic information on their classification.  Volume O of the updated TREATISE ON INVETEBRATE PALEONTOLOGY has been released by the Geological Society of America.  This is the primary reference on Trilobites.  It covers the anatomy and classification of Trilobites, but only goes into depth about two orders, Agnostida and Redlichia.  Additional volumes are coming in the next few years.  There are over 200 pictures of trilobites in Dr. Riccardo Levi-Setti's book TRILOBITES, along with interesting chapters on their anatomy, their amazing eyes, their ability to roll up, and their classification.  This book was never intended to be an encyclopediac compilation of trilobitia, but it is often  frustrating  to try to find information on a particular species without a real index.  The approach in the atlas is often very anecdotal, leading me to feel its true title should be "Trilobites I Have Known."  I always put it down wanting to know more...  for a science book, that's a good thing! Fossils of the Burgess Shale, by Briggs, Erwin and Collier, has a section on the trilobites found at this important site along with pictures of many of the other fascinating creatures found there.   Richard Fortey, who has described many trilobite species, and has written extensively on natural history, has a new book: TRILOBITE! Eyewitness to Evolution.   He describes his leifelong fascination with trilobites and discusses their anatomy, evolution and the history of their role in our exploration of the past.  He humanizes some of the famous personalities in paleontology, and tells us how we know what we think we know about geology and evolution.

I am sure you would agree that non-functional links are very exasperating.  Since I first started this site I have already run into websites that have moved,  busting their links.  So far I have managed to track them down and repair them, but I don't check every link all that frequently.  I try not to keep too many for just that reason, but I do think the ones I have are worthwhile. If you hit a dead one, please let me know and I'll either fix it or remove it.



Eye images above:  Top Row Left to Right:  Comura, Eldredgeia venustus, Hollardops
                              Bottom Row L to R:      Phacops, Drotops megalomanicus, Odontocephalus

Here is a bonus eye.  It is from the Drotops armatus.

Sometimes trilobites can be exasperating.  A Drotops is a Phacops, but an Asaphiscus is not an Asaphus.  However, a Neoasaphus is.  Olenellus is not an Ollenoides, Otarion became Cyphaspis, but  appparently not every Comura became a PhilonyxOgygiopsis and Ogygiocarella aren't even close.  We don't really know what they ate or how they lived.  Oh well...

 A final thought for your consideration.  What if trilobites were still around?  What if humans indulged in selective breeding to develop freaks of nature, as has been done with dogs?  Would they look like this?????


To see the  Home Page

To see the   Cambrian Period Part 1: Agnostida and Redlichiida

To see the   Cambrian Period Part 2: Ptychopariida

To see the   Cambrian Period Part 3:  Asaphida, Corynexochida and Friends
To see the   Ordovician Period Part 1 Asaphida
To see the    Ordovician Period Part 2  Lichida, Phacopida, Corynexochida,  Ptychoparidia and Proetida
To see the   Silurian Period
To see the   Devonian Period Part 1 : Lichida, Corynexochida, Proetida and Harpetida
To see the   Devonian Period Part 2:  Phacopida.


 Thanks for coming!  If you want to know a little bit more about me and find out whose face is on the Machocranus, go to my .Galef Oceanside Asylum Homepage
If you are interested in Dinosaurs, check out my website at  Where the Dinosaurs Are



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