 | Fossils of the Burgess Shale - Cambrian |
Phylum Arthropoda: Trilobite Olenellus,Early Cambrian, Denver Museum of Natural History |
Phylum Arthropoda: Trilobite Alokistocare harrisi, Middle Cambrian,Length of trilobite 1.9 inches |
Trilobite Acadoparadoxides briareus,Early Cambrian, Length of trilobite 18 inches |
Trails: Climactichnites, 505 million years old, Late Cambrian,New York |
Phylum Porifera: Eiffelia |
Polychaete Worms: Canadia |
Polychaete Worms:Burgessochaeta |
Phylum Priapulida:Ottoia |
Phylum Onychophora: |
Hallucigenia Sparsa |
Olenoides serratus |
Artropoda: Canadaspis perfecta |
Phylum Echinodermata: Echmatocrinus |
Phylum Chordata:Pikaia |
Unknown Phyla: Opabinia regalis |
Unknown Phyla:Wiwaxia |
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Cambrian trilobites = most conspicuous, easy to identify.
rapid evolution. approx 90 families. good index fossils for dating (biostratigraphy)
brachiopods - abundant, small, limited diversity
molluscs - small
echinoderms - unusual types now extinct
archaeocyathids - primitive sponge relatives
Most Cambrian animals were herbivores that fed on algae.
A few worm-like animals and arthropods had specialized adaptations for feeding and may have been carnivores.
One of the largest animals to live during the Cambrian was Anomalocaris, about a half-meter long. It had a pair of segmented, spiny appendages near its mouth. Its mouth was encircled by a ring of 32 radiating plates, resembling a slice of pineapple, with inward-facing spines, functioning like teeth in a unique "jaw-like" apparatus. Its size and anatomy suggest that it was a predator. In addition, trilobites seem to have "bites" taken out of them that appear to have been inflicted by Anomalocaris. (Briggs, 1991, American Scientist).
The Cambrian was a time of "evolutionary experimentation" and adaptive radiation. Many body plans were tested, but only a few succeeded during natural selection (predation, competition, etc.).
Many groups of animals appeared, but few succeeded.
The Burgess Shale
530 my (Lower to Middle Cambrian)
University of Calgary Burgess Shale Page
Science Web Burgess Shale Page
Yoho National Park, Canada Burgess Shale site
Wierd creatures of the Cambrian - nice 3D pictures
Paleomod Burgess Shale site
Three dimensional pictures and QuickTime movies of Burgess Shale creatures (from Japan)
MIDDLE CEMBRIOAN
Phylum Porifera: This is a complex globular sponge with a body supported by six-rayed calcareous spicules in various sizes.
Phylum Annelida: Class Polychaeta - Polychaete Worms
This segmented marine worm has bristle-like appendages on each segment which resemble feathers. The head has a pair of appendages which are curved backwards. The digestive tract can be seen passing along the mid-line of the body.Note the pair of appendages on the head, and the segmented body with paired bristle-like biramous (branching into two) appendages.
Phylum Priapulida:Priapulid worm. Note the anterior proboscis (on the left) and the dark trace of the interior digestive tract. Ottoia was carnivorous.
Phylum Onychophora:Aysheaia - a lobe-limbed, segmented animal. Also note the spines on the legs. The head end has a pair of tapering limbs with spines, and three small projections near the mouth. Traces of the digestive tract can also be seen.Note the paired spines (now interpreted to stick up on the dorsal side - or back), and the slightly curved legs. Caterpillar-like
Phylum Arthropoda:
Marrella splendens
Called the "lace crab" by Walcott, Marrella is the most abundant type of animal in the Burgess Shale. More than 15,000 have been collected.
Phylum Echinodermata:The earliest known crinoid. Note the difference between the stem of this specimen and that of later crinoids.
Phylum Chordata: The earliest representative of Phylum Chordata. See the notochord near the dorsal surface. It was a swimmer, but it is not a vertebrate. The rib-like features are muscles.
Unknown Phyla: Opabinia regalis
Note the eyes and the proboscis on the head. Note the paddle-like projections at the posterior end of the body.
