Transcript Fossil Record - Ramsey Public School District

Origins of Biological Diversity
Chapter 15
Fossil Record
• Found in sedimentary rock
• Show clear relationship for
many species over time
example: horse
• Two methods of dating:
1. Relative Dating
2. Radioactive Dating
Relative Dating
• Determine age of fossils
relative to other fossils
in different layers of
rock
• Rock superpositionyounger rock on top of
older rock
• Index fossils- fossils
which we know when
they lived
*determines relative age
Radioactive Dating
• Elements such as 14C
decay/breakdown at steady
rate into another element
• half life- length of time for
half the radioactive atoms
in sample to decay
• # of radioactive atoms in
bodies constant through
time
• Example carbon-14 decays
to nitrogen-14, half life
5,730 years
• Uranium-238 decays into
Lead-206, 4.5 billion years
* Determine actual age
Geologic Time
Scale
• Based on relative and
radioactive dating
• Displays evolution of
life and geologic events
• Divided into eras:
Precambrian
Paleozoic
Mesozoic
Cenozoic
• Eras divided into
periods, periods into
epochs
Precambrian Era
• ~4.6 bya to 580 mya
• 1st prokaryotic cell
• Stromatolites- mats of
photosynthetic bacteria
• 1st eukaryotic cell
• 87% of Earth’s history
Paleozoic Era
• 579 mya to 245 mya
• Age of the Invertebrates
(marine)
• Jawless Fish then Jawed (1st
vertebrates)
• First forests (coal forming)
• Amphibians and reptiles
• Pangea exists
Agnaths
Mesozoic Era
• 244 mya to 65 mya
• Triassic- Age of the
Reptiles, mammal appear
• Jurassic- dinosaurs
flourish
• Cretaceous- first flowering
plants, mass extinction;
climate change
• 135 mya Pangea splits into
Laurasia and Gondwana
Cenzoic Era
•
•
•
•
64 mya to present
Age of the Mammals
Primates evolve
Modern humans 200,000
years ago
• Plate tectonics, present
day positions
Comparative Embryology
• Similar developmental stages in vertebrate
embryos
• Example, gill pouches and bony tails
Comparative Anatomy
VESTIGIAL
STRUCTURES
HOMOLOGOUS STRUCTURES
Comparative Biochemistry
• Same four bases in DNA
• Same 20 amino acids
• Produce similar proteins
(order of amino acids)
• Example, human’s DNA
98.2% similar to chimpanzee
• Example, Cytachrome C 104
aa’s, same in human and
chimp, dog 13 differences,
rattlesnakes 20
• Populations evolve,
individuals do not