ch10

Perserved remains of organisms or traces of their existence

• biogeographic distribution comparative • anatomy - structural morphology • embryology - developmental biology • molecular homology - DNA and amino acid sequences

Minerals in sediment seep into the bone to produce the fossil

Bone decomposes, leaving cavity of the bone

Duplicate of the original fossil remains

Geological records of the activites/behaviours like footprints, nest, etc

• Die in water • Be rapidly buried in sediment with no oxygen • Left undisturbed for a long time • Contain hard body parts

Assigning a fossil a relative age in relation to other fossils and rock strata Strata = layers

Fossils with a known date of origin, used to compare newly found fossils. - Abundant - Distinct - Short lived - Wide geographically distrubition

Fossils that shows traits that are common to both its ancestral group and its descendant group

Comparing the ratio of radioactive isotopes found in fossils to the relatively stable amount found in the atmosphere

Carbon14 to Nitrogen14 Half life of 5730 years Used for Organic material up to 50,000 years old

A structure within a group of species that performs a different function yet has the same structure with a common ancestor

Features of organisms with the same functions but different structures, coming from different ancestors