The Palaeozoic fauna

1. Sepkoski’s Curves

2. The Palaeozoic fauna

3. Brachiopods

4. Corals

5. Graptolites

6. Predators

7. Ecological overview

1. Sepkoski’s Curves

Family diversity

End Permian extinctionOrdovician radiation

Palaeozoic diversity plateau

Palaeozoic fauna

2. Palaeozoic fauna

Corals and other barrier builders

Lie-in-waitpredators

Brachiopods andother filter feeders

Graptolites and other plankton

3. Brachiopods

Pedicle - used to attach theanimal to the sea floor

Diductor muscle –muscles which contractto open the shell

Lophophore – food gatheringand respiratory mechanism.Two arms (brachia) fringedwith cilia generate currents thatbring in food and oxygen

AnteriorPosterior

Adductor muscle –muscles which contractto close the valves Stomach

MouthMantle – sheets oftissue which line theshell

Dorsal

Ventral

Muscle scars – canbe used to identifycertain species

TeethCardinal process –diductor muscleattachment site

Brachidium –lophophore support

Ventral valve

Dorsal valve

B.

A.

4. Corals

Calcareousskeleton

Outer cell layer, with stingingcells on tentacles

Inner cellwall,responsiblefor digestion

Corals are cnidarianslike jellyfish and seaanemones

Basic coralmorphology

Coral diversity through time

5. GraptolitesC

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Benthicdiversity Planktonic diversity Faunal description

Maximum diversity of graptolites,around 200 species worldwide.High degree of faunal provinciality withtwo major provinces, a low latitude Pacificprovince and a higher, southern hemisphereAtlantic province. Four and two stipedgraptoloids common.

Dendroid graptolites move from thebenthos into the plankton. Different thecaltypes are lost. Number of stipes reduces,but degree of regularity of the rhabdosomeincreases rapidly. True graptoloids,dominated by forms with a virgella, quicklyappear.

Fauna dominated by graptoloids with two thecaearranged back-to back. These diplograptidspecies showed more variety of thecal shape thanhad been seen before, with boxy thecae andcurved thecal walls becoming common. V- andY- shaped graptoloids evolve.

Only one genus of diplograptids survives the end-Ordovician extinction event. Thisgroup evolves into monograptids, which have a single stipe.

Monograptids radiate into a variety of forms with curved or spiral stipesand complicated thecae. Thecae become isolated, asymmetrical, hooked,spinose. Cyrtograptids evolve; monograptids that produce branches fromspines on their thecae and have a spiral form.

Saetograptids, robust monograptids, often withspines on their early thecae, radiate. Retiolitids,unusual graptoloids with a skeletal frameworkaround the rhabdosome, become common.

Morphologically simple monograptids undergo aseries of minor radiations and extinctions.

Benthic graptolites evolve from a common ancestorof graptolites and pterobranchs. Maximumdiversity of benthic forms in the late Cambrian andearly Ordovician.

Dendroid graptolites become extinct.

First planktonicgraptolites are dendroidsQ. Rhaphidonema

Diplograptid faunaI.’Climacograptus’J. DicellograptusK. Dicranograptus

Dichograptid faunaL. DidymograptusM. ‘Isograptus’N. Phyllograptus

Anisograptid faunaO. ClonograptusP. Staurograptus

Monograptid fauna - LowerSilurianF. NormalograptusG. SpirograptusH. ‘Monograptus’E. Cyrtograptus

Monograptid fauna - UpperSilurianC. RetiolitesD. Saetograptus

Monograptid fauna -DevonianA., B., simple ‘Monograptus’

Pterobranch

Planktonicgraptoloid

Benthicdendroid

6. Predators

Trilobites

Nautiloids

Conodonts

7. Ecological overview

1. Palaeozoic fauna takes over slowly

2. Fauna reaches higher diversity than before

3. Includes mud grubbers like trilobites from Cambrian fauna

4. Includes filter feeders and macrozooplankton

5. Increased niche space above seafloor

6. Includes greater predator pressure

7. Survives mass extinctions at end Ordovician and end Devonian

8. Wiped out at end Permian