Early animal diversification produced trilobites, brachiopods, archaeocyaths, sponges, and unusual soft-bodied assemblages.
Approximate span539–485 million years ago
Best evidenceAnatomy + stratigraphy
Collector ruleKeep formation data
Common collector material
- trilobites
- brachiopods
- archaeocyaths
- small shelly fossils
Using the period in identification
The period provides a plausibility test. Compare the claimed organism’s known temporal range with the formation, locality, matrix, and associated fossils. A correct period cannot rescue incorrect anatomy, and a familiar-looking fossil can still be mislabeled when it comes from the wrong unit.
Marketplace cautions
- Rounded ages may differ by tens of millions of years.
- “Dinosaur age” is often applied broadly to any Mesozoic material.
- Reworked fossils can erode from older rocks and become deposited in younger sediments.
- Commercial formation names may be incomplete, outdated, or used as regional shorthand.
Collection record
Record both the seller’s stated age and the evidence supporting it. Preserve the original label even if later research changes the interpretation.
Build a comparison set
Use listings to compare morphology, matrix, preparation, locality claims, dimensions, repairs, and seller disclosure. Similar appearance alone does not establish identity or legality.
Compare collector listings