EARLY PALEOZOIC LIFE Cambrian Explosion Evolution’s “big bang” lasted about 10 million years All principal animal phyla except Bryozoa appeared between 535 to 520 myBP The Cambrian Explosion

EARLY PALEOZOIC LIFE By the Ordovician, global biodiversity tripled Included trilobites, brachiopods, bivalve molluscs, gastropods and coralline animals Ordovician mountain building may have created new habitats The number of infaunal organisms increased Continuing Diversification

EARLY PALEOZOIC LIFE Foraminifera First appeared in the Cambrian Survive to present Unicellular Organisms (Protistans) Platysolenites, a Cambrian foram Agglutinated form Calcareous skeleton

EARLY PALEOZOIC LIFE Radiolaria First appeared in the Cambrian, more abundant in mid-Paleozoic Survive to present Have a siliceous skeleton Unicellular Organisms (Protistans)

EARLY PALEOZOIC LIFE Archeocyathids (“ancient cup”) Early Cambrian phylum Have similarities to both corals and sponges Associated with stromatolites Reef-builders of Early to Middle Cambrian 60 m thick, 200 km long Extinct at end of Cambrian Metazoan Invertebrates

EARLY PALEOZOIC LIFE Archeocyathids (“ancient cup”) Metazoan Invertebrates

EARLY PALEOZOIC LIFE Phylum Porifera (sponges) Early Cambrian phylum Evolved from colonial flagellated, unicellular organisms Conservative evolutionary history All but one modern class of sponges were present in Cambrian Exist to present Metazoan Invertebrates

EARLY PALEOZOIC LIFE Phylum Porifera (sponges) Metazoan Invertebrates

EARLY PALEOZOIC LIFE Phylum Porifera (sponges) SPICULES Metazoan Invertebrates Spicules – Composed of Calcium carbonate

EARLY PALEOZOIC LIFE Phylum Porifera (sponges) SPICULES Metazoan Invertebrates Spicules – Composed of Silica

EARLY PALEOZOIC LIFE Phylum Porifera (sponges) SPICULES Metazoan Invertebrates Spicules – Composed of Spongin

EARLY PALEOZOIC LIFE Metazoan Invertebrates Phylum Porifera (sponges) Cambrian Protospongia

EARLY PALEOZOIC LIFE Metazoan Invertebrates Phylum Porifera (sponges) Ordovician

EARLY PALEOZOIC LIFE Metazoan Invertebrates Phylum Porifera (sponges) Silurian Astylospongia Caryospongia

EARLY PALEOZOIC LIFE Metazoan Invertebrates Phylum Porifera (sponges) Silurian Palaeomanon

EARLY PALEOZOIC LIFE Metazoan Invertebrates Phylum Porifera (sponges) Silurian Astraeospongia Star-shaped spicules

EARLY PALEOZOIC LIFE Metazoan Invertebrates Stromatoporoids Calcareous sponges Geologic range: Ordovician to Present Built reefs in the Silurian (Michigan Basin) Found in Caribbean Sea, Mediterranean Sea and Pacific Ocean

EARLY PALEOZOIC LIFE Metazoan Invertebrates Stromatoporoids Side view Laminae and Pillar Structure

EARLY PALEOZOIC LIFE Metazoan Invertebrates Stromatoporoids Top view

EARLY PALEOZOIC LIFE Metazoan Invertebrates Cnidaria (Coelenterata or Corals) Includes Sea fans Jellyfish Anemones Corals Very diverse group Stinging cells – cnidocytes Radially symmetrical

EARLY PALEOZOIC LIFE Metazoan Invertebrates Cnidaria (Coelenterata or Corals) Jellyfish Fire coral Sea fans, gorgonian Horn corals Tabulate corals Modern corals

EARLY PALEOZOIC LIFE Metazoan Invertebrates Cnidaria (Coelenterata or Corals) Two forms: Polyps and Medusa Polyps – asexual Medusa - sexual

EARLY PALEOZOIC LIFE Metazoan Invertebrates Cnidaria (Coelenterata or Corals) Stinging cells Cnidocytes

EARLY PALEOZOIC LIFE Metazoan Invertebrates Cnidaria (Coelenterata or Corals) Stinging cells or Cnidocytes

EARLY PALEOZOIC LIFE Metazoan Invertebrates Rugosa (Rugose or Horn Corals) Ranged from Ordovician to Permian Not major reef formers, colonizers Usually solitary Abundant in Silurian and Devonian reefs

EARLY PALEOZOIC LIFE Metazoan Invertebrates Rugosa (Rugose or Horn Corals)

EARLY PALEOZOIC LIFE Metazoan Invertebrates Rugosa (Rugose or Horn Corals)

EARLY PALEOZOIC LIFE Metazoan Invertebrates Rugose growth