deep time

____ are evidence of past life and provide direct evolutionary history of life on Earth

fossils

what fossilizes?

hard body parts

trace fossils

chemical fossils

hard body parts

bones, teeth, shells, wood

trace fossils

remnants of the activity of a living creature

chemical fossils

biological molecules formed by the organisms that are released by the organism in life or left behind after the organism dies

sedimentation

the accumulation of small particles that are transported by wind and water and that eventually settle on the bottom of bodies of water

over time, layers build up and become sedimentary rock

sedimentary rocks

one kind of rock carried by water and wind is swept somewhere else

most recent on the top

create layers over time (oldest on bottom)

deposits of rocks and minerals gradual layering and compaction over time

power of fossils

geologists can correlate sedimentary rocks by comparing the fossils found within the rocks

index fossils

species  that existed for a relatively short period of geologic time and found over large geographic areas are the best for precise correlations

radiometric dating

absolute dating with radioactive isotopess

radioactive isotopes

decay at a very predictable rate (measured in half lives). comparing the ratios of parent and daughter isotopes allows us to estimate the age of a rock

half life

time required for the amount of radionuclides to reduce to half

parent vs daughter isotope

practice 2 kinds of half life questions

probability of becoming a fossil

hard body parts > soft body parts

live in sediment under wtaer > live in water column > live in sediment out of water > fly > walk around on surface

how are fossils maintained/destroyed?

compaction

preservation

exposure

destruction

compaction

the compression and possible distortion of the fossil from the pressure of layers on top of it

• turns sediment and fossils into rock

preservation

chemical substitution of hard parts by soluble minerals from the surrounding stone, especially calcium carbonate (limestone)

exposure

erosion, geological uplifting, human/biotic activities

destruction

from exposure, geological subduction/metamorphosis, etc

older fossils have more…

opportunities to be moved and/or damaged

some continents are being ripped apart

because of movement of plates

subduction

one goes underneath the other

mountains are often formed due to this

plate tectonics over geologic time

1. difficult for fossils to be formed

2. many fossils are destroyed

3. difficult to find

and if a fossil makes it through all of these things, we still need to find it (very rare)

false: gaps in the fossil record disprove evolution

MISCONCEPTION

we dont know all fossils because not found

hard for fossils to be formed and found

fossil record

fossils are evidence of past life and provide a direct evolutionary history of life on earth

what can we learn from different types of fossils

• teeth/jaw

• limbs

• skull

fossils can reveal more than just age, anatomy, and identity

can tell diet, locomotion, senses, physiology, habitat, and more

C4: plants- grasses, savannahs

transitionary fossils

linking 2 major groups

represent “intermediate” forms of life during an evolutionary transition

• remeber evolution has no goal

if we fossilize when we die, we will all be transitionary fossils for human descendants 10 milion years from now

Tiktaalik (375 Mya)

evolutionary transition between fish and tetrapod amphibian

fish-like: gills, scales, fins…

tetrapod-like: shoulder, elbow, wrist, mobile neck

Archaeopteryx (150 Mya, Jurassic)

evolutionary transition from dinosaur to birddinosaur like: teeth, claws, abdominal ribs, bony tail

Brid like: feathers, wings

Hoatzin- bird in south america

Ambulocetus (45Mya)

transition from land tetraploids to cetaceans (whales, dolphins)

modern sperm whale: only a small bony remnant of pelvic bone remains

transition from land tetraploids to cetaceans

1. pelvis- reduction of the hind pelvis and limbs, and adapted for swimming

2. changes in eye position from dorsal to more lateral and nasal opening from snout tip to single blowhole

3. changes to mandibular foramen- from little space to an enlarged space with oil used forhearing in modern toothed whales

4. dental anatomy- shift from variety of teeth, some complex, to all simple and prong-like

evolution is ___ a great chain of being

NOT

evolution does not imply “progress”

both species can continue existing after evolution

evolutionary success

microevolution

• lots of offspring

• population lasts

macroevolution

• not going extinct

• passing on new species

morphological stasis

little to no change over long periods of geologic time

“living fossils”- species showing morphological stasis that are still alive today

rate of ____ change does not always match rate of ___ change

morphological, genetic