Paleozoic LifePaleozoic Life

Vertebrates & Plants

Paleozoic VertebratePaleozoic VertebrateIntroductionIntroduction

• Vertebrate evolution

• Transition from H2O to land

• Time of major extinctions (end of Paleozoic Era)

– Fish amphibian reptile

– Plants preceded animals

– Method of reproduction Evolution of the seed = plants Amniote egg = animals

– Marine invertebrates

– Many amphibians and reptiles

Paleozoic VertebratePaleozoic VertebrateFish EvolutionFish Evolution• Ancestors– Similar to amphibians – May have evolved from sessile suspension feeders

• Class Agnatha – Jawless fish• Class Acanthodians – 1st Jawed fish

Jawless fish

• Most primitive vertebrate -- fish

Paleozoic VertebratePaleozoic VertebrateFish EvolutionFish Evolution

– Oldest fish Upper Cambrian

– Phosphatic; Jawless fish, class Agnatha

– Earliest non-marine Silurian

– Shallow near-shore marine deposits

Anatolepis piece, U. CambrianOstracoderm

Paleozoic VertebratePaleozoic VertebrateDevonian SeafloorDevonian Seafloor

Paleozoic VertebratePaleozoic VertebrateEvolution of JawsEvolution of Jaws

• Major Advancement– Active predators – Eat plants – New niches

• “Evolutionary Opportunism”– Early jaws for respiration

– Open mouth wider; more O2 – Led to ↑ food consumption

Placoderms

• Class Acanthodians– L. Silurian– Extinct Permian

Paleozoic VertebratePaleozoic VertebrateLate Devonian SeafloorLate Devonian Seafloor

Paleozoic VertebratePaleozoic VertebrateCartilaginous & Bony FishCartilaginous & Bony Fish

• Class Chondrichthyes (cartilaginous)

– Related to sharks, rays, skates – Primitive sharks – L.

Devonian

– Devonian

• Class Osteichthyes (bony fish)– Devonian

– Two groups Ray finned Lobe finned

Paleozoic VertebratePaleozoic VertebrateBony FishBony Fish

• Ray finned • Lobe finned– Thin bone spread from body

– Fresh-H2O beginning

– Trout, bass

– Muscular fins; no radiating fins

– Articulating bones

– 2 types of lobe-finned

• Lobe-Finned Types

Paleozoic VertebratePaleozoic Vertebrate2 Types of Lobe-Finned2 Types of Lobe-Finned

– Lung Fish

– Crossopterygians

Lungs evolved from sac-like bodies

Adapted for H2O variations

Amphibian evolution

Most important

Rhipidistian

Lung fish

Paleozoic VertebratePaleozoic VertebrateLobe-finned & Amphibian SimilaritiesLobe-finned & Amphibian Similarities

• 1st Vertebrates on land – L. Devonian

Paleozoic VertebratePaleozoic VertebrateAmphibiansAmphibians

– Plants 1st land organisms

– Spiders and insects before vertebrates

Crossopterygians

• Major Barriers

Paleozoic VertebratePaleozoic VertebrateTransition from HTransition from H22O to LandO to Land

– Dessication

– Reproduction (need H2O)

– Effects of gravity

– Extraction of O2 from atmos.

• Crossopterygians overcame Barriers– Backbone– Limbs

– Lungs

• Amphibians exploit new niches

• Amphibians limited to colonizing land

Paleozoic VertebratePaleozoic VertebrateEvolution of ReptilesEvolution of Reptiles

– Gelatinous egg laid in H2O

• Amniote egg

• Led to colonization all parts of land

– Embryo surrounded by liquid

– Miniature adult

– “Anion” provided yolk (food sac)

Bypass larval stage

– No need to return to H2ORecent gelatinous egg

Paleozoic VertebratesPaleozoic VertebratesReptilesReptiles

Pennsylvanian reptile, HylonomusEvolution

Reptiles evolve in Late Mississippian•Protorothyrids = earliest reptiles•Diversified in Permian—displaced amphibians—more successful•Pelycosaurs evolve from protorothyrids

•Extinct in Permian•Pelycosaurs succeeded by therapsids

•Mammal-like reptile•Both carniverous and herbivorous•Endothermic—warm-bloooded

•Could occupy both cold and warm niches—high and low latitudes

•2/3 reptiles and aphibians extinct at close of Permian.

• Marine fresh H2O land

Paleozoic VertebratePaleozoic VertebratePlant EvolutionPlant Evolution

• Problems to solve– Dessication– Support– Effects of gravity

• Vascular (seedless)

• Non-Vascular– Earliest plants mid-late Ord

– No specialized cells– Live in low, moist areas

– Specialized cells

– Movement of H2O

– Earliest middle Silurian

– Reproduction (needs H2O)

• Gymnosperms (flowerless seed plants)

Paleozoic VertebratePaleozoic VertebrateSeed EvolutionSeed Evolution

– Late Devonian

– Seed plants no longer restricted to wet areas

– Male and female cones

• Major source of world’s coal

Paleozoic VertebratePaleozoic VertebratePermian FlorasPermian Floras

– Results from alteration of plants living in low, swampy areas