Evolutionary Faunas
• The expansion and decline of these faunas
– changes in dominance & changes in diversity through time
• Marine Evolutionary Faunas
• 1) Cambrian, 2) Paleozoic, and 3) Modern
diversify together
diversifies more slowly but has higher diversity
step-like pattern in increasing diversity
associated with decline of previous fauna
similar rates of taxonomic turnover – response to mass extinction
Ecologic Characteristics
• Cambrian Fauna – broadly integrated communities dominated by generalized
deposit feeder and grazers and low tiering (epifaunal and infaunal)
– What is tiering?
• Paleozoic Fauna – dominated by epifaunal suspension feeders with
complex tiering and more guilds
– Occupied more ecospace
• Modern Fauna – more guilds and large numbers of durophagous predators
and mobile deep infauna, and epifaunal tiering is reduced
Trends
• (Sepkoski and Miller, 1985) – evolutionary faunas form coherent
assemblages within shelf environments
• Cambrian Fauna – spread across the entire shelf in early Paleozoic
but restricted to deeper water environments later in Paleozoic
• Paleozoic Fauna – established in shelf environments at expense
of earlier faunas.
• At same time (later in Paleozoic), early forms of the Modern Fauna become
established in shallow shelf and more hostile environments
• Permian mass extinction ends dominance of Paleozoic Faunas on shelf
Compositon and History
• Cambrian Fauna
- trilobites, inarticulate brachs., hyoliths, eocrinoids
- diversified rapidly from Vendian to Middle Cambrian – Cambrian Explosion
- Max. diversity in early Late Cambrian
- Cambrian Fauna began to decline as Paleozoic Fauna diversified and decline
helped by end Ashgil and Frasnian mass extinctions
Composition and History
- Paleozoic Fauna
- dominated by articulate brachiopods with crinoids, corals, ostracodes, cephalopods,
and bryozoans
- Ordovician Radiation – global diversity tripled
- Max. diversity from Late Ordovician to Devonian
- Long slow decline
- Major reduction at the end of the Permian – mass extinction
Composition and History
• Modern Fauna
- dominated by gastropods and bivalves, bony and cartilage fish, bryozoans,
and echinoids.
- Long slow diversification
• Terrestrial Biotas
• Plants
• Silurian – Devonian
• Pteridophte – Late Devonian – Early Carb.
• Gymnosperm – Early Carb. – Mesozoic
• Angiosperm – Early Cretaceous – Present
Composition and History
• Tetrapods
• labrinthodonts, anaspsids, synapsids – Middle – Late Paleozoic
• diapsids, dinosaurs, pterosaurs – Mesozoic
• everything else - Cenozoic