Silurian and Devonian

Chapter 11 Historical Geology

the Silurian and Devonian should be interepreted as a

widespread, uniform environment

reef core

interlocking skeletal material of dominant species - today corals and calcareous algae, in past architeuthids, stromatoporoids and other sponges, bryozoans, crinoids, brachiopods

fore-reef facies

material broken off by wave action accumulates as coarse debris (frequently breccia) on a talus slope forming an apron of coarse, poorly sorted angular debris on a deeper water side

back water facies

lagoon; low energy deposits - stratified apron of sand-sized overwash

barrier reef facies

long, linear masses w/ shallow platform on one side and deep marine basin on the other; steep front absorbs incoming wave energy

reefs show what

ecological succession

the pioneer stage of a reefs are dominated by

crinoids, small corals, and brachiopods that stabilized sea bottom

the intermediate stage of reefs are dominated by

corals and stromatoporoid sponges

the mature stage of reels description:

the core of the reef is entirely massive corals and sponges of climax community that can stand wave pounding flanks are crinoids, brachiopods, and bryozoans that prefer quiet water

the earliest fishes were

jawless

two basic body types of fish during paleozoic

flat bodies with upward facing eyes or round bodies w/ simple slit-like mouths, bony armor, and tails to propel their heads upward

when did fish rapidly diversify

in late silurian

anatomy and embryology suggest jaws evolved from

gill arches

why were jaws likely evolved

to develop hinge for respiration (pump more water over gills)

what were the first jawed fish

acanthodians

what was the dominant fish in the devonian

placoderms

what was the “age of fishes”

devonian

what is the ancestor to land vertebrates

osteolepiforms

what is the new group that is ancestors to land vertebrates (most successful in coastal and inland waterways)

Tetrapodomorpha

what ancestor did land plants evolve from

green algae

to have the first unequivocal land plants, they must overcome

desiccation, fluid transport, and reproduction

how did plants overcome dessication

created a cuticle to help retain water

how did plants overcome fluid transport

created a vascular system

what is one of the best known vascular plants from the devonian

rhynia

lycophytes

living club mosses and “ground pine” - separate male and female cones allow cross-pollination

archaeopteris

known as seed fern, evolved in late devonian, produced first modern-looking forest w/ dense leaves; EXTINCT AT END OF DEVONIAN

we see an increase or decrease in plant diversity to late devonian

increase

changes due to land plants in late devonian:

we see first coals, wildfires, stabilization of stream habitats (used to be braided) and first black shales

plant extinctions are different from animal extinctions bc

they are more vulnerable to climate change, mass mortality, and extinction due to competition

first land animal to exploit the decaying fauna is

millipede

what fish developed jaws that rose up instead of down to allow feeding in shallow water

tetropodmorpha

what were reasons for fish to move onto land

basking (to raise body temp), which causes digestion faster, grow and mature faster, and reproduce more successfully

what was the first amphibian

tiktaalik

the 4-5th largest extinction occurred in the

late devonian

how many of the marine species died out during the devonian

70%

the first wave of extinction hit the

trilobites, brachiopods, armored jawless fish, most lobe-finned fish, and jawed placoderms

the second wave the extinction hit was the

algal community, and placoderma

the only fish left after devonian extinction were

jawless fish, bony fish, and sharks