chapter 15 fossils

what are fossils

they are the preserved rains of once-living organisms (can also impressions)

how do fossils form

must be covered immediately after death by dust/material so that oxygen doesn’t reach the body and decompose it. the hard structure inside will mineralize and become a fossil.

what is a fossil record

is an assemblage of fossils in order of age, which provides evidence of change over time; it’s the entire collection of fossils found.

What can fossils tell us

they can help us understand descent with modification & evolution, provide evidence for evolution, different species emerged over time due to natural selections, changes overtime in a single family of organisms

what are the two ways fossils can be dated

radiometric dating and relative dating

what is relative dating

less accurate, dating something relative to the time around it. e.g. the rock above the fossil is 20 years old the rock below it is 25 so the fossil must be 20-25 years old.

what is radiometric dating

what state the carbon in the organism is. if we know the state and ratio of carbon we can figure out how old the fossil is, sues radioactive isotopes to measure the age of fossils in surrounding areas.

what is a trace fossil

indirect evidence of fossils (footprints, burrows,poop)

what is a body fossil

a physical body fossil

how does anatomy and dna support evolution

an organisms anatomy reflects adaptation to its environment. a changed environment provides opportunities for the selection of new adaptations. m

what is an example of anatomy and dna supporting evolution

tetrapods are vertebrae with four true limbs. jointed, bendy appendages with digits. All tetrapods share the same forelimb bones, which are arranged in the same order of 1-2, lots of littles. 

what are homology or homologous structures

similar structures due to inheritance from a common ancestor. biological structures that are shaped by different organisms because it was inherited from a common ancestor, even if those features have evolved to serve different functions. 

vestigial structures

structures that are inherited from ancestors that modern day versions don’t need. they lose the need and use for the structure, so they evolved it away. there can be remnants on organisms. 

true or false: the genetic code is nearly identical in all organisms 

true af