Early Paleozoic (Cambrian - Ordovician):
* Dominant: Marine invertebrates
* Trilobites: Abundant, diverse, and often used as index fossils for this period.
* Brachiopods: Filter-feeding bivalve-like creatures.
* Cephalopods: Nautiloids, early relatives of squid and octopus.
* Graptolites: Colonial animals, mostly known from their fossilized skeletons.
* Corals: Early reef-building organisms.
* Emergence: First vertebrates: Jawless fish began evolving.
Middle Paleozoic (Silurian - Devonian):
* Dominant: Marine life diversifies:
* Jawed fish: Rapid evolution of diverse fish types, including sharks and bony fish.
* Coral reefs: More extensive and diverse reefs develop.
* Trilobites: Still abundant, but start to decline in diversity.
* Brachiopods: Remain abundant and diverse.
* Significant Event: First land plants appear in the Silurian.
* Emergence: First amphibians: Transition from water to land.
Late Paleozoic (Carboniferous - Permian):
* Dominant: Amphibians and reptiles
* Giant insects: Dragonflies and other insects reach enormous sizes due to a high oxygen atmosphere.
* Seed ferns: Dominant plants, forming vast forests.
* Amniotes: Reptiles evolve, adapting to dry land with eggs that have a protective membrane.
* Significant Event: Formation of supercontinent Pangaea.
* Extinction: The Permian-Triassic Extinction: The largest mass extinction in Earth's history wipes out over 90% of marine species and 70% of terrestrial vertebrate species.
Key Points:
* The Paleozoic Era saw a remarkable explosion of life forms, transitioning from simple marine life to diverse ecosystems on land.
* Each period is characterized by its own dominant species, with key events shaping the course of evolution.
* The late Paleozoic witnessed a significant shift in dominance from marine to terrestrial life, paving the way for the Mesozoic Era.
