Late Neoproterozoic (Early Proterozoic ~ 1 0.5 BYA)
The beginnings of modern life took place in the late Neoproterozoic
Explosive animal evolution in the last 30 MYA of the Neoproterozoic
trace fossils
imprints of soft bodied animals most related to jellyfish
(Phylum Cnidaria) Ediacaran Fauna but also included annelid
worms and arthropods (crabs, lobsters, insects)
skeletal fossils calcium carbonate vase- and tube-shaped
skeletons
The Cambrian Explosion (0.5 BYA)
Early Paleozoic life fossil record is all from marine deposits, but it is assumed that protests and fungi inhabited freshwater terrestrial environments by this time
First time that modern fauna occurred
Early Cambrian tube or vase-shaped, or teeth (Fig. 13.1)
Tommotian Fauna (Fig. 13.2) lasted 3 or 4 million years,
Small animals including the first sponges and first mollusks with
skeletons were composed of calcium carbonate and calcium phosphate
skeletons support tissue and permit locomotion
Large Animals with Skeletons last few million years of the Late Cambrian, larger animals that belong to phyla that have lived into the modern
Large predators may have lead to the demise of the Ediacara
fauna
Anomalocarids large predatory arthropods (Fig. 13.6)
Trilobites (Fig. 13.3) arthropods with segmented skeletons that survived to the end of the Paleozoic, most were benthic epifauna, but some were planktonic
Mollusks - monoplacophorans
Brachiopods (Fig. 13.5)
Eocrinoids (Fig. 13.7)
Stromatolites much less abundant in the Cambrian than in the Proterozoic, probably due animal grazing
Reefs early mounds formed by archeocyathids (sponge-like suspension feeders; Fig. 13.8)
Middle and Late Cambrian spanned ~ 15 MYA
Marked by expansion of several pre-existing groups, especially the trilobites, echinoderms and brachiopods
Conodonts (Fig. 13.00) earliest vertebrates with abundant teeth
Fish evolved at this time fossil record of tiny bone plates (13.10)
Burgess Shale Fauna (Fig. 13.11) spectacular fauna of
soft-bodied animals, best preserved in the Rocky Mountains of
British Columbia