Life of the Paleozoic ► Overview of expansions  Cambrian, Vast expansion of shelly marine life forms and jawless fish  Ordovician - most modern phyla established  Late Paleozoic- land plants and vertebrates (tetrapods and amniotes)

Invertebrates ► Marine environments  Nektic, planktic, benthic ► Adaptions:  Epifaunal- animals living on the sea floor  Infaunal – animals that burrow into the sea floor  Mobile  Review of Proterozoic fossils ► Cloudina ► Ediacaran

Early cambrian ► Small Shelly fossils  Rarely more than a few millimeters long ► A- Anabarella ► B- Camanella ► C- Aldanella ► D- Sponge Spicule ► E- Formitchella ► F- Lapworthella

Early Soft-body fossils ► The Burgess shale:  Most fossils reduced to shiny black impressions ► What type of fossilization is this?  Viewed as one of the most important finds of the fossil record ► Altogether, over 60,000 species have been collected

The Burgess shale ► Four Groups of Arthropods  Trilobites  Crustaceans  Scorpions  Insects ► Sponges ► Onycophorans ► Crinoids ► Sea Cucumbers ► Chordates ► Unknown species

Chordates ► Shows evolution of early notochord ► Notochord- dorsally situated nerve cord  Why is this important? ► Notochord is precursor to vertebral column ► Pikaia- small animal that has notochord and also shows evidence of v-shaped muscle bands (this indicated sinosoidal swimming motion ► THESE ANIMALS ARE ANCESTORS TO ALL MODERN VERTEBRATES

Other notable fossils ► Anomalocaris- fierce predator over 50cm long (~2ft) ► Opabinia- five eyes, flexible nozzle ► Hallucigenia- seven pairs of legs, seven dorsal spines, claws, cylindrical trunk. (Considered to be a onycophoran) ► Marrella- Four spines extended back from cephalon The most common arthropod found in the burgess shale

Protista (unicellular groups) ► Foraminifera (Calcerous Microfossils)  Range from Cambrian to present  More numerous and varied by Carboniferous  Global distribution during Pennsylvanian-Permian ► Radiolarians (Siliceous Microfossils)  Range early Paleozoic to present  Most abundant in Mesozoic rocks

Cup Animals : Archaeocyathids ► Conical of vase-shaped skeletons ► Extinct by the end of the Cambrian ► Earliest known reef builders  Found in N. America, Siberia, Antarctia, Australia

Porifera ► Pore-bearing animals ► Appear to evolved from colonial flagellated unicellular creatures ► Cambrian representatives of all but one modern class are known as fossils (Have not changed much)

Fossil Porifera Modern Sponges

Corals and Cnidarians ► Main Groups  Sea Anemonies  Sea Fans  Jelly Fish  Hydra  Reef-forming Corals

Body of Cnidarians ► Three main layers  Ectoderm: Outer layer or body wall  Endoderm: Inner layer ► Contains:  Primitive sensory cells  Digestive cells  Nutritive cells  Mesoglea: Thin intermediate layer

Body Form ► Polyp ► Medusa

Brachiopods ► Most abundant, diverse, and useful Paleozoic fossil group ► Braciopods are bivalves, however, each valve (shell) differs in shape and size. ► Unlike clam shell which can be considered right and left brachiopod shells are distinguished between dorsal and ventral. ► Most valves are made of Calcium Carbonate. ► Ornamented with radial ridges, grooves, spines, nodes and growth lines.

Groups of Brachiopod ► Articulate Brachiopods  Valves are hinged along the posterior margin and are prevented by sliding sideways by teeth and grooves ► Inarticulate Brachiopods  Lack a definite hinge structure  Valves held together by muscle ► Both are filter feeders attached to sea floor by fleshy stalk (pedicle) ► Lophophore: hair like structures that circulate water and food toward mouth

Fossil Brachiopods

Mollusks ► Gastropods (snails)  Earliest forms constructed small conical shells, by late Cambrian/early Ordovician most had developed the more recognizable coiled shell.  By Pennsylvanian gastropods extremely abundant and even air-breathing species had developed  Cephalopods- may be the most advanced and complex of all invertebrates

Cephalopods ► Represented today by:  Squid  Cuttlefish  Octopods  Chambered Nautilus

Ammonites ► Goniatites, the first ammonite, appears during the Devonian ► Other Ammonites

Arthropods ► Includes:  Lobsters  Spiders  Insects  All animals that have chitonous exterior skeletons, segmented bodies, and paired,jointed appendages

Trilobites

Trilobites

Eurypterids ► Scorpion like bodies ► Found in Marine and Brackish facies ► Ordovician-permian

Echinoderms ► Spiny-skinned animals ► Five way symmetry ► Exclusively marine- typically bottom dwelling, either attached or mobile  Group includes ► Starfish ► Sea Urchins ► Crinoids ► Crystoids

Echinoderms ► Appear to have developed during late proterozoic ► Ediacaran, Arkarua, also had five way symmetry  Stemmed or stalked echinoderms first occur in mid cambrian (not abundant until Ordovician)

Continental Invertebrates ► Fossil evidence is less complete  Why? ► However as plants begin to invade continent so do animals ► Record begins with possible Millipede tracks in Ordovician rocks. ► Body Fossils of Centipedes and Millipedes occur in Silurian rock ► In New York, Devonian rocks have yielded fossil centipedes, spiders and other wingless arthropods ► Insects do not become common until the late Missipian ► The Pennsylvanian witnessed the arrival of flying insects like the dragon fly ► Coal swamps from the Pennsylvanian yielded a dragon fly with a wingspan of over 2 ft.

Vertebrates ► Fishes  Dermal Plates (Upper Cambrian)  Scales and Plates (Ordovician)  Five Taxonomic classes: ► Agnatha (jawless fish) ► Acanthodii (Archaic jawed fish) ► Chondrichthyes (cartilaginous fish) ► Osteichthyes (Bony fish)

Agnatha ► Earliest known (early Cambrian)  Myllokunminga  Haikouichthys Other species include Theolodus, Jamoytius, Pteraspis (armored) and Hemicyclapsis Other species include Theolodus, Jamoytius, Pteraspis (armored) and Hemicyclapsis

Acanthodii ► Arose during Silurian ► Most numerous during Devonian ► Extinct during Permian

Chondrichthyes ► Late Devonian to Present ► Represent shark, rays, and skates ► Cladoselache- late paleozoic shark

Osteichthyes ► Bony Fish can be divided into two groups  Actinoptergians ► Lack a muscular base to their paired fins ► Also lack nasal passage to the throat  Sarcoptergians ► Had sturdy, fleshy lobe-fins ► A pair of openings in upper mouth that led to external nostrils ► Were able to rise to surface to take in air that was passed onto functional lungs (Lung Fish)

Sarcoptergians ► Two major roups lived during the Devonian  Dipnoans ► Dipnoans- track does not lead to evolution of tetrapods but does include some present day freshwater living species of lungfish in Australia and Africa  Crossopterygians ► Because of the pattern of skull elements, arrangement of bones in their fins, and the structure of their teeth, Crossopterygians are considered to be the ancestor of the earliest land inhabitants

Crossopterygians & Tetrapods

Tetrapods ► Tetrapods are four- footed vertebrates  Amphibia, Reptilia, Mammalia

Tetrapods ► First to come ashore did not leave the water completely  Amphibians ► Return to water to lay eggs ► From eggs come fish-like larvae that develop in water ► Number of changes had to accompany the shift to land

Shift to land ► A three chambered heart developed ► Limb and girdle bones had to be modified to overcome gravity ► Spinal column became more sturdy but yet flexible ► To better assist hearing the Hyomandibular (fish) transformed into an ear ossicle-the stapes ► The fish spiracle (a vestigial gill slit) became eustacian tube and middle ear

Fossil Record of Basal Tetrapods ► Late Devonian  Ichthyostegids ► Retained many features of their fish ancestor  Tail fin  Bony gill covers  Fish-like vertrbae  Skull bones similar to crossopterygians  Labyrinthic folding of enamel ► Due to this following species are referred to as Labyrinthodonts ► During the Carboniferous large numbers of these Labyrinthodonts wallowed in swamps and streams

Evolution of the Tetrapods ► Among some of the tetrapods were some vertebrates that evolved a way of reproducing without having to return to water  Development of the amniotic egg ► These animals are referred to as Amniotes  During the Carboniferous Amniotes diverged into two groups ► Reptilia: anapsids, diapsids, and archosaurs ► Synapsids- Mammal-like reptiles

Synapsids ► Although the synapsids are called “mammal- like reptiles, cladistic analysis shows that they should not be termed reptiles  Most spectacular synapsids, Pelycosaurs ► Some sported big sail-like structures ► Varied group  Carnivores: Dimetrodon  Herbivores: Edaphosaurus

Plants of the Paleozoic ► Overview  Cambrian: Stomatolites and stromatolitic reefs  Ordovician to Silurian- ► Receptaculids (Green Algae) ► Four-spore tracheophytes (vascular plants) and Bryophytes (mosses)  Silurian: Three spore tracheophytes  Early Paleozoic: Chlorophytes and fungi formed lichens

Effects of Plants ► Roots slowed erosion ► Transpiration changes atmospheric conditions ► Provide shelter and food for land animals ► Leaf litter and decay form early soils

Vascular Plants ► First unquestionable vascular structures appear during Middle Silurian  Some fossils show plants up to 30cm tall  Horizontal stalks (Rhizones)  Vertical stems and spore sacs

Vascular Plants ► Although early vascular plants were small, evolution would soon lead to the development of wood. ► By late Devonian lofty, well-rooted trees appear  One such forest stood near Gilboa, New York ► Some of these trees stood over 7m tall (21 ft)  Another covered the Sahara

Plants of the Carboniferous ► Lycopsids: Scale trees.  Present day Lycopsids consist of the Club Mosses, such as Lycopodium  Not so small during the carboniferous  Lepideodendron reached 30 meters tall

Sphenopsids ► Lived side by side with Lepidodenrons  Living relatives include horse tails ► Fossil Sphenopsids posses slender, unbranching, longitudinally ribbed stems with thick cores and leaves at each joint.

Seedplants ► Seed plants arrive in the late Paleozoic  Most likely evolved from Devonian fern-like plants, however, reproduced purely through seeds  Become the dominant plant type by the late Paleozoic. ► Most widely known: Glossopteris ► Ginkgo only modern day survivor

Mass Extinctions ► Ordovician  Two Phases ► 1 st Phase – Planktonic and Nektonic organisms  Graptolites, acritarchs, nautiloids and some trilobites, bryozoa, coral and brachiopods ► 2 nd Phase- several of the remaining trilobites perish and corals and bryozoans severely reduced  Most likely caused by global cooling associated with the growth of the Gondwana Ice Caps

Mass Extinctions ► Devonian  In the late Devonian we see huge decrease in Trilobite numbers and varieties. Also large decrease in reef building corals, brachiopods, and placoderms.  These extinctions occur over a 20 million yr period so probably not due to catastrophic event (meteor) ► What other events are occurring that may lead to this?

Mass Extinctions ► Late Permian  Referred to as “the mother of mass extinctions”  90% of all pre-existing marine species disappear  On land, spore bearing plant give way to conifers, cyads and othe gymnosperms. ► Vegetative change causes chain reaction in land animals ► Many families of basal tetrapods, primitive reptiles and synapsids disappear.