80
70
60
50
Millions of
40
years ago
30
20
10
opossum
devil
koala
kangaroo
Sequences from a ~100,000 year old marsupial fossil was compared to corresponding sequences
from opossums and devils with the results shown:
type I
↓
type I
↓
opposum: ...AGCATATAATGTAGA...
fossil: ...AGCTAATAATATAGA...
devils: ...AGCTTATCATATAGA...
↑↑
type II type III
type I: same in fossil and devil; different
in opposum (670,000)
type II: different in fossil only (44,220)
type III: different in devils only (44,667)
How long did the fossilized marsupial lineage evolve after it diverged from the devil lineage?
Assume the fossilized marsupial lineage went extinct at the time the bone started fossilizing and
that mutation rates are the same in all three species. Show your work for credit.