Late Paleozoic
Terrestrial Life (continued)
Significantly different from the Devonian
New insects and spore trees in the Mississippian, replaced by seed trees in the Permian
Coal deposits developed in lowland swamps, wetlands much more extensive than today
Dominant coal swamp flora:
Lycopods spore plants up to 30 m tall and 1 m diameter trunks
Lepidodendron
Sigillaria
Seed ferns were the undergrowth, difficult to distinguish from
spore ferns
Glossopteris
High dry ground Plants
Sphenopsids spore-bearing plants, characterized by a jointed
hollow stem
Cordaites seed plants up to 30 m high, gymnosperms (naked
seeds), related to conifers (cone-bearing)
Freshwater and Terrestrial Animals
Freshwater ray-finned fish and sharks flourished
Clams became important in freshwater and brackish environments
Insects, assumed an important ecological role
First insect was early Devonian and wingless
By Late carboniferous many kinds of insects had wings
Developed foldable wings, legs modified
Amphibians the only land vertebrates during the Early
Carboniferous
Variety of sizes and shapes and sizes, up to 3 m long, herbivores
and carnivores
Reptiles
Oldest are Pennsylvanian (Upper Carboniferous)
Biggest difference from amphibians is mode of reproduction
Ecothermic cold-blooded, rest frequently to absorb heat from the environment
Amniote Egg an egg that provides the embryo with: 1) a yolk for nutrition; 2) two sacs, one that holds the embryo (amnion) and one that holds waste products; 3) durable outer shell
Allowed vertebrates, for the first time, to live and reproduce
away from water
Reptiles also evolved advanced jaw structure permitting heavy
pressure with sharp teeth for puncturing and ripping food apart
Pelycosaurs fin-backed reptiles, top carnivores, Permian,
Dimetrodon
Therapsids evolved from these
Therapsids powerful jaws, legs positioned more vertically, differentiated teeth, hair, endothermic (maintained body temperature at constant level, but not as constant as mammals), enhanced predators capability to sustain activity
Paleogeography
Continents were merging to eventually form Pangea
Glaciation on Gondwanaland into the Permian
Early Carboniferous limestones and glaciers
Early Late Carboniferous Transition drop in sealevel and mass extinction
Later Carboniferous continental collision and latitudinal temperature gradients steepened (coal swamps not far from edges of continental glaciers) shown by tree ring growth, early greenhouse world followed by burial of C in coal reduced greenhouse effects, Continental glaciers to nearly 30 N-S latitude
Permian complex topography and steep climatic gradients,
most of Pangeo was too dry to support coal swamps, so most were
large deserts (Permian Coconino Sandstone, AZ)
Glossopteris dominated the landscape
Reef growth around the northern margin of the Delaware basin in west Texas
Mass Extinctions
1) end of the Guadalupian 70% of marine species died out, including most reef fauna and large fusilinids, onset of deep sea anoxia
2) terminal Permian extinction 80% of all species went extinct (C isotope curve), associated also with onset of global water column anoxia
proposed to be a meteor impact (Becker 2001)
Evidence: crater not yet found, buckeyballs filled with helium
(no Ir), sand dikes