Wednesday, January 6, 2010

Cryptolithus Trilobite Information

Creature existed in the Ordovician Period (about 488 to 443 million years ago) defined by the English geologist Charles Lapworth in 1879 after the Welsh tribe called Ordovices.  This period occurred in the Paleozoic Era (consists of: Cambrian, Ordovician, Silurian, Devonian, Carboniferous (in U.S. Mississippian/Pennsylvanian), and Permian Periods).

The taxonomy of the Cryptolithus tessellatus
Domain: Eukaryota
Kingdom: Animalia
Subkingdom: Bilateria
Branch: Protostomia
Phylum: Arthropoda
Class: Trilobita
Order: Asaphida
Family: Trinucleideae
Genus: Cryptolithus

I found two papers North American Biogeography and Taxonomy of Cryptolithus(Trilobita, Ordovician) by Fredrick C. Shaw and Pierre J. Lespérance, Journal of Paleontology 68(4), 1994, pp. 808-823 and Viola Group (Ordovician Oklahoma) Cryptolithinid Trilobites: Biogeography and Taxonomy by Fredrick C. Shaw, Journal of Paleontology 65(6), 1991, pp. 919-935 that describe the Cryptolithus in more scientific detail.

They describe the habitat as being water of at least 30 meters (approximately 98 feet) in depth with muddy sediment.  The trilobite was thought to be blind and a bottom feeder.  In addition, it was isolated for millions of years in a cool water shelf like environment.

The Cryptolithus (Green, 1832) trilobite remains I find east of the Louisville, Kentucky area are in what is called the Kope Formation.  I find small brachiopods, cepholopods, and crinoid stems with the Cryptolithus fossils.

One might also check out the website: for more information.

Pleurodictyum Coral

These coral pictures were sent to me by Dave in Pennsylvania. He found these fossils in the Mahantango Formation formed in the Devonian Period.  The corals are Pleurodictyum.

He pointed out in his message to me, "The interesting thing about the molds is you can see what the coral colony originally started to grow on. One grew on a worm tube and the other looks like it grew on a Modimorpha pelecypod. The latter mode is much more common in the thick mudstones found at Seven Stars where I've found many pelecypod shells encrusted with Pleurodictyum colonies. Kind of like the Aulopora colonies that are common on the Paraspirifer et. al. brachiopods found in the Silica Shale. It gives you insight into the environment they lived in. Since there was no solid substrate to colonize, they grew on exposed or washed in shells."

Nicely researched and very good finds.

These first two pictures are of the Pleurodictyum styloporum.

These last three images are of Pleurodictyum lenticulare or Pleurodictyum americanum.