Test II Review Sheet handed out.

Late Paleozoic marine life:

Marine life of the Devonian:
Tabulate-stromatoporoid reefs continue to flourish, supporting large and diverse ecosystem

Eurypterids begin to decline, but still present

Ammonoids:

• Descendants of nautiloid-grade cephalopods
• Also shelled, and mostly coiled
• More complex sutures
• Very common, very diverse, very short-lived species: excellent index fossils
• Beaks modified into pumps: probably planktonivores

MAJOR fish radiation: Devonian sometimes called “age of fish”
Advanced fish begin with bony exoskeleton and partly bony endoskeleton.
Some major groups:

• "Ostracoderms":
  • Armored jawless fish
  • A grade, not a clade)
  • Front ends generally heavily mineralized, rears covered with smaller scales
  • Mostly sediment feeders
• Acanthodians
  • Generally considered a clade, but possibly a grade
  • Most primitive known jawed fish
  • Probably actively pursued prey
• Placoderms:
  • More complex jawed fish
  • Did not have teeth, but instead a ridge of bone for cutting
  • Some bottom feeders, others major predators
  • Fronts heavily armored; body skeleton less mineralized
• Chondrichthyians:
  • "Cartilaginous fish"
  • Sharks and their ancestors
  • Bony tooth-like scales, but cartiligenous skeletons
  • Diverse in Devonian, although none resembling the modern mako/great white/etc. type
  • Included various predators, shellfish eaters, etc.
• Actinopterygians
  • "Ray-finned fish"
  • Clade including most modern fish
  • Rare in Paleozoic, become more common in Mesozoic
• Sarcopterygians
  • "Lobe-fins": paired fins have long bones down the main axis
  • Important clade from Devonian onward
  • Sarcopterygians include:
    • Coelacanths: become more common in later Paleozoic and Mesozoic
    • Lungfish : once very widespread in both marine and terrestrial environment, adapted for surviving periods of ponds drying up
    • Stegocephalians: terrestrial vertebrates and their ancestors (more about them later)

With expansion of swimming predators (eurypterids in Silurian, ammonoids and jawed fish in Devonian), major shift in prey species: trilobites and jawless fish decline in diversity.

Late Devonian mass extinction:

• Not at end of Period, but between last two Ages
• More than 40 percent of marine genera die out
• Associated with pulses of anoxic water onto epeiric seas, possibly glacially driven
• Victims include acritarchs, "ostracoderms", placoderms (a few survive into Mississippian), tabulate-stromatoporoid reef complexes

Marine life of the Mississippian:
Many groups (tabulates, stromatoporoids, trilobites, placoderms) never recover in diversity from Late Devonian mass extinctions.

Others flourish: crinoids and blastoids do amazingly well, as do lacy bryozoans, brachiopods, ammonoids, sharks and actinopterygians.

Crinoid meadows: huge fields of crinoids and associated organisms.

Fusulinids: a type of foraminferan (armored single-celled eukaryote) appear: more important in Pennsylvanian.

Marine life of the Pennsylvanian:
Much as in Mississippian.

Fusulinids highly diverse, become important index fossils.

Marine life of the Permian:
Permian reef community: sponges and bryozoans as primary framework builders.

Brachiopods are extremely abundant, particularly large sediment sitters.

End of Permian: largest extinction in history of the marine realm: see next lecture

Late Paleozoic terrestrial life: Plants
Plants continue the "conquest" of land started in the Ordovician.

Devonian flora:
Rhynia:

• Spore-bearing vascular plant with spore organs at tops of upright stalks
• Common in Early Devonian
• Named after the Rhynie Chert, which contains the remains of many early terrestrial plants and arthropods
• Development of various tougher vascular tissue for support: wood or wood-analogues.

Other Devonian plant developments:

• Development of leaves:
  • Increase surface area for more photosynthesizing, allowing for more energy (i.e., faster growth)
  • Increase surface area for stomata, allowing for more "breathing" (good for faster growth and in response to decreased CO₂ in atmosphere
• Plant activity helps hold soil together
• Plant activity tends to bind carbon (in soils, coals, and the plants themselves), contributing to decrease in global CO₂ levels

New groups of plants in Devonian:

• Lycopods:
  • Club mosses and their relatives
  • Grow by shoots just underneath soil
  • Become trees during Mississippian; important trees of the Coal Swamps
• Ferns
• Sphenopsids (horsetails and their relatives, recently discovered to be a type of fern)
• Archaeopteris:
  • A Late Devonian spore plant with wood = a "progymnosperm"
    • True wood is otherwise only present in seed plants
  • Up to 20 m tall, one of the oldest known trees
• Seed plants
  • Internal fertilization of plant, so do not need external moisture to reproduce
  • Pollen lands on sex organ of plant, is bundled into a seed that can fall off and sprout when conditions are favorable
  • Early seed plants include so-called seed ferns, so-called because grossly resembled ferns

Carboniferous flora:
Convergent evolution of the tree among many sorts of vascular plants. Diverse forests.

Major groups:

• Scale trees:
  • Arborescent (tree form) lycopods
  • Mississippian through Pennsylvanian
  • Most important genera are Lepidodendron and Sigillaria of the Pennsylvanian
  • The main trees of the swampy lowlands: need moisture to reproduce
• Calamites:
  • Arborescent sphenopsids
  • Segmented trunks, grow by underground shoots
  • Most important genus is Calamites
  • Better adapted to drier conditions than scale trees, but still needed moisture to reproduce: lived along river banks and floodplains
• Cycads:
  • Seed plants, appear in Pennsylvanian, but unimportant until Mesozoic
• Cordaites:
  • Seed plants, close relatives of the conifers
  • Reached up to 30 m (as did Lepidodedron) or more, possibly as high as 50 m!
  • Major tree former in the upland regions
• Conifers:
  • Cone-bearing seed plants (today includes spruces, pines, redwoods, etc.)
  • More important in Mesozoic and Cenozoic than in Paleozoic

As the world began to dry out during the Late Pennsylvanian, scale tree and calamite forests decline as seed plant forests rise. Scale trees and cordaites die out at end of Pennsylvanian.

Permian flora:
Calamites die off in Early Permian.

Coal swamps decline over most of the world (not in China and in high latitudes of Pangaea).

Glossopteris: a "seed-fern" which was the most important member of the Glossopteris Flora of Gondwana. Adapted to upland, drier, cold environments.

Also, first ginkgos (not important until Triassic).

Conifers also diversity in Permian.

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Last modified: 10 January 2008