EARLY PALEOZOIC LIFE

Cambrian Explosion

Evolution’s “big bang”

lasted about 10 million years

All principal animal phyla except Bryozoaappeared 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 CambrianSurvive to present

Unicellular Organisms (Protistans)

Platysolenites, a Cambrian foramAgglutinated form

Calcareous skeleton

EARLY PALEOZOIC LIFE

Radiolaria

First appeared in the Cambrian, more abundant inmid-Paleozoic

Survive to presentHave 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 Cambrian60 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 inCambrian

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 LIFEMetazoan Invertebrates

Phylum Porifera (sponges)Cambrian

Protospongia

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Phylum Porifera (sponges)Ordovician

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Phylum Porifera (sponges)Silurian

Astylospongia

Caryospongia

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Phylum Porifera (sponges)Silurian

Palaeomanon

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Phylum Porifera (sponges)Silurian

AstraeospongiaStar-shaped spicules

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Stromatoporoids

Calcareous sponges

Geologic range: Ordovician to Present

Built reefs in the Silurian (Michigan Basin)

Found in Caribbean Sea, Mediterranean Seaand Pacific Ocean

EARLY PALEOZOIC LIFEMetazoan Invertebrates

StromatoporoidsSide view

Laminae and Pillar Structure

EARLY PALEOZOIC LIFEMetazoan Invertebrates

StromatoporoidsTop view

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Cnidaria (Coelenterata or Corals)

Includes

Sea fansJellyfishAnemonesCorals

Very diverse groupStinging cells – cnidocytesRadially symmetrical

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Cnidaria (Coelenterata or Corals)

Jellyfish

Fire coral

Sea fans, gorgonian

Horn corals

Tabulate corals

Modern corals

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Cnidaria (Coelenterata or Corals)

Two forms:

Polyps and Medusa

Polyps – asexual

Medusa - sexual

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Cnidaria (Coelenterata or Corals)

Stinging cellsCnidocytes

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Cnidaria (Coelenterata or Corals)

Stinging cells or Cnidocytes

EARLY PALEOZOIC LIFEMetazoan 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 LIFEMetazoan Invertebrates

Rugosa (Rugose or Horn Corals)

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Rugosa (Rugose or Horn Corals)

EARLY PALEOZOIC LIFEMetazoan Invertebrates

Rugose growth