Introduction 1 Middle Paleozoic Era a 85 Ma 444 359 Ma i Silurian 28 Ma 444 416 Ma ii Devonian 57 Ma 416 359 Ma b Major orogenic events occurring c Global eustatic changes i Unconformity formation d Time of firsts in biosphere 2 Silurian a Sea level rise fall i Flooding widespread marine rocks on cratons b Marine radiation post Ordovician ME c First jawed fishes d Colonization of land habitats i Early plants in Silurian e Acadian orogeny i Tilted deposits in England 3 Devonia a First ammonoids b Radiation of jawed fish c First insects d First trees forests e First amphibians f Antler orogeny W Laurentia g Global cooling Marine Diversification 1 Rediversification of marine life after the Ordovician ME a Brachiopods highly diversified b Bivalve mollusks spread to non marine habitats c Graptolites 5 times diversification of species 2 Reefs coral stromes re flourishes a Increasing size until end Devonian enormous i Rugose wrinkled horned outnumbered tabulate tabulae 3 New nektonic swimming invertebrates internal structure a Ammonoids i Most prominent new invert swimmers ii Evolved from coiled cephalopod mollusks nautiloids in the early Devonian iii Rapid diversification and dominance excellent index fossils 1 Devonian to late Mesozoic a Extinction at KT boundary b Eurypterids i Distant relative to modern scorpions ii Swimming predators iii Conspicuous evolved earlier in Ordovician iv Arthropods many with claws v Lived in brackish and freshwater 4 Jawless fish diversified greatly during the Silurian a Oldest fully preserved and diverse specimens of fish are in the Silurian Devonian rock b Fragments of skeletons found in early Paleo i Agnathans became conspicuous in mid Paleo c Marine d Freshwater e Diversification Jawless fish i ii Jawed fish iii Bony skin fish iv Cartilaginous fish v Bony fish 1 Ray finned 2 Lobe finned f Ostracoderms bony fish i Common 1 Few survived past the Devonian ii Paired eyes iii Lacked jaws iv Covered with bony armor v Various morphology 1 Curved belly elongated lower fin swimmers 2 Flattened belly elongated upper fin bottom dwellers 5 Jawed fish a Acanthodians i Elongated fish with numerous fins supported by sharp spines ii First fist group to possess several modern features 1 Paired fins 2 Covered by scales not bony plates a Major adaptive breakthrough for predators b Placoderm i Armor like bone ii Very large fish iii Predatory fish was at the top of the food chain iv Primarily freshwater v Marine known from late Devonian 1 Dunkleosteus a 7 m long armored fish skull 1 m long b Armor protected eyes c Possessed bony teeth d Possessed an unarmored tail for easy locomotion c Cartilaginous fish i Mid Devonian marine appearance ii Primitive sharks iii 1 m length iv An important fish group in Devonian seas d Ray finned fish i First appearance in Devonian 1 Dominate Mesozoic Cenozoic 2 Modern trout bass herring tuna ii Fin bones that radiate from body iii Major difference from modern fish 1 Asymmetrical tail 2 Non overlapping diamond shaped scales e Lobe finned fish i Fins are attached to the body by a single shaft ii Mainly freshwater fish iii Originated in Devonian but only 3 genera survive today iv Lungfish 1 Gulp air so they can survive in stagnant evaporating pools of water during the dry season v Ancestor of all terrestrial vertebrates Terrestrial Invasion 1 Early Paleozoic and Precambrian terrestrial environments were likely populated by simple life forms algae cyanobacteria fungi a Barren rock and soils b Little humus covered land c No forests no meadows 2 One of the most important biohistory events during the mid Paleozoic was the terrestrial invasion of plants 3 Early terrestrial plant invasion is in the Silurian a First definitive fossil evidence b Vascular plants required that algae protists experienced two special mutations i Evolution of a rigid stem 1 To stand upright in air ii Evolution of a root system 1 To anchor the plant 2 To collect water and nutrients 4 Lycopods Include tiny club mosses a b Some grew to the proportion of trees i Petrified remains supply coal c Water is essential within the spore reproductive cycle d Thus confined to aquatic habitats 5 Seed plants appeared in the Devonian a Evolved from vascular spore plants b The seed was an important adaptive evolutionary breakthrough c Freed land plants to invade further inland 6 Seed plants trees a Appeared abruptly and covered Earth b Formed world s first widespread inland forest 7 Animals colonized land after plants expanded a Delayed migration i Base of food web on land needed to be built ii Animals needed a suitable habitat 1 Protection from sun and heat 8 First land animals were invertebrates a Millipedes and flightless insects early Devonian i Fed on organic detritus b Scorpions centipedes and spiders mid Devonian i Carnivores 9 First terrestrial vertebrates amphibians a Evolutionary emergence of amphibians from lobe finned fish 10 Anatomical evidence indicates amphibians vertebrates are most closely related to fish Juvenile amphibians live in water Juveniles mm into air breathing adults but return to water to lay eggs a b c Complex tooth structures of the Devonian amphibian Labyrinthodonts similar to Devonian lobe finned fish d A group of Devonian lobe fin fish had lungs lungfish which adult amphibians also possess 11 Tikaalik a Late Devonian missing link between lobe fin fish and amphibians b Had traits from both lobe finned fish and amphibians i Fishlike fins and scales ii Fishlike lower jaw iii Amphibian like flat skull iv Lungs v Shoulder joints vi Flexible wrists on fins vii Finger like bones viii Flexible neck to raise head ix Eyes and nostrils on top of head 12 Ichthyostega was a common primitive amphibian during late Devonian a Possessed true legs b Likely fed on fish Earth System Shift 1 Plants a Altered landscapes i Before anchoring plants braided streams were abundant meanders once erosion subsided ii Late Devonian fossil root traces are abundant 1 Stabilized the soil against erosion b Provided habitat c Provided a land based food source d Paved the way for terrestrial faunal invasion e Most important adaptive breakthrough responsible for the increase in the size of land plants was the evolution of broad leaves i Captured sunlight higher rate of photosynthesis f The origin of seed plants permitted inland expansion of forests 2 Widespread expansion of land plants in Devonian caused CO2 to decline a Acceleration of weathering root acids b Photosynthesis c Resulted in a