1. 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

2. 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

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

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

5. 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

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

7. 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

8. EARLY PALEOZOIC LIFE
Phylum Porifera (sponges)
Metazoan Invertebrates

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

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

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

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

13. EARLY PALEOZOIC LIFE
Metazoan Invertebrates
Phylum Porifera (sponges)
Ordovician

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

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

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

17. 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

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

19. EARLY PALEOZOIC LIFE
Metazoan Invertebrates
Stromatoporoids
Top view

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

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

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

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

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

25. 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

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

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

28. EARLY PALEOZOIC LIFE
Metazoan Invertebrates
Rugose growth