Chapter25 Flashcards
taxa
end of a tree thats not a species
derived trait
modified ancestral traits
Homoplasy
populations evolve similar traits but not from common ancestory, instead adaptations from environmental pressures
intact fossil
no decomposition
compression fossil
Forms when sediments accumulate on top of the organism and become cemented into rocks such as mudstone or shale. The sediments’ weight compresses the organic material below into a thin, carbonaceous film.
Cast fossil
Forms when organisms decompose after they are buried. The hole that remains fills with dissolved minerals, which create an accurate
cast of the remains.
Permineralized fossil
Forms when organisms decompose extremely slowly. Dissolved minerals gradually infiltrate the interior of cells and harden into stone
Trace fossil
Forms when sedimentation and mineralization preserve indirect evidence of an organism in the environment, including footprints, tracks, burrows, feeding marks, and feces.
habitat bias(fossil)
Organisms that live where sediment is actively being deposited (e.g., beaches, swamps) are more likely to fossilize than are organisms in other habitats
Taxonomic and tissue bias
Some organisms (e.g., those with hard parts such as bones or shells) are more likely to decay slowly and leave fossil evidence
Temporal bias
More recent fossils are more common than ancient fossils
Abundance bias
Organisms that are abundant, widespread, and present for a long time leave evidence much more often than do species that are rare, local, or ephemeral
Phanerozoic Eon
Paleozoic, Mesozoic, Cenozoic eras
Paleozoic Era
Ancient life
Begins major animal lineages
initial diversification
ended with 90% extinction
Mesozoic Era
Begins where Paleozoic extinction ended
ends with extinction of dinosaurs
dinos and gymnosperms
