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 3
ASAPHIDA, CORYNEXOCHIDA AND FRIENDS
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.
ASAPHIDA ORDER
Superfamily Anomocaroidea
Family: Pterocephaliidae
2cm McKay Group; Radium, British Columbia
CORYNEXOCHIDA ORDERSuborder: Corynexochina
Family: Dorypygidae
4.8cm Pierson Cove Formation; Millard County, Utah
Family: OryctocephalidaeFamily: Zacanthoididae
9mm Lower Spence Shale; Oneida Narrows, Idaho
8mm Chisholm Shale; Caselton, Lincoln County, Nevada
3cm, including pygidial spines
This specimen was sold as A. longwelli, and I have been told that it is more likely to be A. schenki. On longwelli, the pygidial spines are splayed outward, rather than pointed straight back and curved inward as seen on this one. More recently I was told that it is neither as both of those species have seven thoracic segments and this one has six. Ergo, it is an undescribed species of Albertella.
SOME OTHER INTERESTING CAMBRIAN FOSSILS
Gogia was an early echinoderm that somewhat resembled a crinoid and is sometimes called a "Dawn Crinoid".
Chancelloria looks like a sponge and is often called a "Glass Sponge", but the spines are hollow instead of solid as they are in sponges. It is classified in the extinct phylum Coeloscleritophora.
THE BURGESS SHALE
This is me, using my laser finger pointer Close-up of the
to show the location of the famous Walcott Quarry
Burgess Shale in Yoho National Park, B.C.
(No, I didn't feel like a six mile hike, up 3000
feet to see it closer. Maybe next year.)I have included several links to Burgess Shale Websites on the last page of this site.
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 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
