Dating fossils
What is an index fossil?
Its a fossil that is used to identify geological age. Sometimes its too difficult to age a fossil so they use one found in a similar site and similar rock to compare. p388
Which one of these words would indicate a longer time ago - Mesozoic, Jurassic, Cambrain, Archaen?
Archaean - think of the english word archaic and go with these is only one thing older hadean, any other period, eon, era word is younger
Breakdown the word stromatolite
Stroma is the fluid in chloroplasts. Now known to contain materials that can be used in the light independent stage of photosynthesis
The -lite suffix refers to rocks, minerals and fossils.
Bats behavior is to be active at night, they are often known to feed of fruit and nectar of plants. Much like a bee bats can be pollinators. If a bat and flowering plant have a mutualism relationship and have adapted over a long time would this be an example of convergent, divergent, prallel or co-evolution?
Co-evolution
What features makes a good index fossil?
One that is found in only one layer (stratum) and one that is found at multiple sites (good geographic spread)
What is stratigraphy?
Its the layers of the rocks that can be used to age fossils found in them.
Which of these would promote the longevity of a species the most -
A - low competition for food, B - no predators, C - reproduction rates that produced lots of offspring, D - a stable environment with suitable adaption features
D - stable environment requires less adapting, but also if the population is adaptable then small changes such as sickness or slow changing climate allow time to adapt
Would carbon dating be suitable for aging a mummy?
Yes because a mummy is carbon based.
For something to be the same species what must it be able to do?
Produce fertile offspring.
If they can't then they are different species or hybrids
In stratigraphy is the highest ot the lowest stratum to the atmosphere older?
Lower down is older
What is a deficit or difficulty in relative dating?
Which spans the shortest length of time - eons, eras, periods or epochs?
epochs
What is hand axe?
It's not what you think from bunnings with wooden handle.
Its a prehistoric hand tool made of stone. Often quartz, but not carbon.
It can't be dated by Carbon 14 radiometics.
Song birds are named for a reason - suggest a mechanism that isolates related but separate species of song birds.
Behavioral isolation - such as singing/vocalisation, or even breeding times.
Is it possible to have a stratum with no fossils? How?
Yes stratums can have no fossils, maybe at the time the conditions did not allow for fossilisation/preservation.
What is used for absolute dating?
Radiometrics or known radioactive decay of isotopes such as Carbon 14 compare to Carbon 12.
The Cenozoic era is the most recent - within this era are named epochs. Why/How were scientists able to differentiate this era into not only periods but also epochs?
More understanding of the fossil record, ability to reach/excavate to a depth in this era, as other older eras are far deeper.
Think critically if asked to age something you have no idea about - think of key events
age these from oldest to youngest - adaptive radation of mammals, dinosaurs go extinct, angiosperms evolve, H sapiens evolve, first algae, great extinction
1. Nothing lived until there was some bacteria so first algae must be the start
2. Humans weren't around with dinosaurs
3. Angiosperms are flowering plants - what things ate fruits?
Based on these 3 ideas
first algae, then we know we had a great extinction and plants had to start again, which led to angiosperms, ________, ________, H sapiens evolve
The choice between dinosaurs and adaptive radiation is the last decision. Adaptive radiation is quick, so I put dinosaur extinction first followed by adaptive radiation
The wings of bats and birds are both homologous and analogous. How can they be both?
Homologous (common origin but lead to divergent species)- they are known to be forelimbs coming from tetrapods
Analogous (non common origin but lead to common purpose) - they are known to have formed independently as wings
If one stratum has shells and crustaceans and the one above it has tree leaves and land dwelling teeth as fossils what can this tell you about the environment at the times?
It may indicate a change in sea levels at that location from marine (with shells) to land (with terrestrial fossils)
What is a disadvantage of radiometric for dating?
Some half lives are not suitable to date very very old fossils as there is so little of the isotope left. Carbon 14 becomes unreliable after 60,000 years. **interesting graph in your book about C reducing and N increasing p390
In dating as Potassium 40 decreases what is produced?
In dating as Carbon 14 decreases what is produced?
Potassium 14 decreases and argon gas increases
Carbon 14 decreases and is compared to the amount of carbon 12 to age something. Nitrogen increase is also noted.