GEOL 008 Lecture 9: 09 - Cambrian Explosion
Document Summary
First appeared 3. 5 ga (or 3. 5 ga) Eventually, single celled organisms joined up into multicellular organisms. Multicellularity arose independently in many lineages, many time (plant, animal fungi) Loosely defined as all the unknown weirdos right before the cambrian. Over 100 species arose during the explosion few of which seem related to later organisms. Largely extinct by the start of the cambrian, probably due to the evolution of predators. Cloudina - tube-like animal possibly related to corals or worms. Hard parts give an organism protection and allow for sturdier bodies. The first known hard part organism was already victim to predators. Most major animal groups (phyla) appear in the fossil record. Large bodied, visible things with hard parts. Sudden appearance of animal phyla in the fossil record could mean two. Animals evolved into many diverse forms at the start of the. Animals diversified earlier but all developed hard parts at the start of the cambrian.
