Cambrian Gastropod from Ben Suardal
The Cambrian period lasted from about 545 up to about 495 million years ago. The start of the Cambrian period was more active than at the end. Mountains were still being created but only in a few parts of the world. By the end everything had quietened down somewhat and was much calmer. Land was being gently eroded by shallow seas, leaving most of what is now the British Isles, under water. Certain types of sponges that are now found in the rocks all around the world, seem to suggest that the climate was very likely quite warm.
Animals and plants were still confined to the water so no life existed on dry land. At the beginning of the Cambrian period, many types of invertebrates were existing in the waters and seas. Brachiopods and trilobites evolved. The trilobites took over the seas and developed into many forms and soon began to outnumber the over invertebrates. Sponges, worms and jellyfish evolved along with molluscs and early echinoderms. Plant life was probably a lot slower to evolve, but this is difficult to know with any certainty as the only recorded plant remains found in rocks from this period today are of calcareous algae (a type of seaweed).
GEOGRAPHY AND CLIMATE: Sea level rise, sandstone and limestone deposited,
Atmospheric levels of oxygen rise, North America and Eurasia separate.
TERRESTRIAL ANIMAL LIFE: No life on land.
PLANT LIFE: No plant life.
SEA LIFE: Primitive algae and seaweeds, Jellyfish, Sponges, Starfish
Worms, Velvet worms, Shelled animals appear, Trilobites and
Brachiopods dominant, Reefs built archaeocyathids.
