Page 109 - Science Course 3 (Book 1)
P. 109
Mo3-L1b: What is the Evidence for Evolution?
The fossil record contains evidence that five mass extinction events have occurred during the Phanerozoic Eon
Extinct Events
4,000
3,000
Late Permian
Late Ordovician (singular Genus) Number of Genera
Late Devonian Late Triassic 2,000
1,000
Late Cretaceous
500 400 300 200 100 0
Millions of Years Ago (mya)
The fossil record contains evidence of the appearance of many new species over time.
Biological evolution is the change over time in populations of related organisms.
The fossil record is evidence that horses descended from organisms
for which only fossils exist today.
Eohippus Mesohippus Merychippus Pliohippus Modern Horse
Front leg
and Foot
55 – 50 35 – 25 35 – 5 5 – 1
1 – Present
day
Millions of Years Ago(mya)
Key Concept
What is the Evidence for Evolution?
How are fossils evidence of biological evolution?
SUMMARY
What is the Evidence for Evolution?
Scientists use fossils as evidence that
species have changed over time.
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