AMONG MY TRILOBITES The Cambrian period, named for Cambria, an area in Wales, began 570 million years ago and lasted until 504 million years ago. During this time major modern phyla of multicellular organisms appeared. Probably descending from segmented worms, trilobites developed hard exoskeletons, eyes and the ability to grow by shedding their old shells. They diversified and become the dominant life-form in the oceans. Both the largest and the smallest trilobites lived during the Cambrian. There were more families of trilobites during this era than at any other time.THE CAMBRIAN PART 1
AGNOSTIDA AND REDLICHIIDA
TO LEARN MORE ABOUT EACH ORDER OF TRILOBITES, CLICK ON ITS NAME. THIS WILL TAKE YOU TO SAM GON'S WEBSITE FOR A DESCRIPTION. USE YOUR BROWSER'S BACK BUTTON TO RETURN TO THIS PAGE.
AGNOSTIDA ORDER Suborder: Agnostina
Family: Peronopsidae Family: Diplagnostidae 
7mm Wheeler Formation, Delta, Millard County, Utah
Family: Ptychagnostidae 
8mm Wheeler Formation; Millard County, Utah
REDLICHIIDA ORDER 
6mm Marjum Shale; House Range, Utah
Suborder: Olenellina
Family: Holmiidae 
10.7cm Morocco
Specimens of this species have appeared for years as "Andalusiana". When I first went to the Tucson Show I bought a somewhat larger specimen that was pretty heavily coated with some sort of resin and I am pretty sure that there were areas of outright reconstruction on the pleurae. It was surrounded by the fairly typical Moroccan-style grooved matrix, which makes hiding mix and match recombination of pieces from several different animals easier. I bought this one at the most recent 2006 Show . It has the negative counterpart and fine surface detail is very nice. The eyes are more easily seen on the counterpart. Many fossils are prepared by putting the parts back together and prepping down to reveal the trilobite with all of its parts intact. That is usually not done with Moroccan Cambrian material, at least partly because they display well without such efforts and partly because the quality of the shell preservation doesn't make it very easy. Anyhow, I spent a lot of time comparing this and another similarly sized and identically priced trilobite with better eyes. I ended up picking this one as the tail end of the other was tucked underneath and the axial spines on this one were much nicer. That is one of the advantages of shopping at a Show where a variety of specimens are available.
This is the fossil I referred to above. I removed the surface of the matrix and a lot of areas of resin are evident around the back half. The "before" image is below. The differences in surface texture of the fossil itself are pretty dramatic as well. The overall shape does fit with the description for this species in the Treatise
13.2 cm
Family: Olenellidae
2.4cm (including tailspine) Pioche Formation; Lincoln County, Nevada
3.5cm Pioche Formation; Lincoln County, Nevada
4cm Pioche formation; Lincoln County, Nevada
2.5 cm Pioche Shale; Lincoln County, Nevada
Suborder: Redlichiina
Family: Redlichiadae
Family: Paradoxididae 
2cm Hunan Province, China
7.8cm Morocco
Family: Dolerolenidae 
13.8cm Morocco
5cm Morocco
2.7cm Skreje shale, Jince formation; Bohemia, Czech Republic
7.5mm Hunan Province, China
To see the Home Page
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.
To see the Carboniferous Period, the Permian Period, some Trilo-trivia and Links
