?
What are the four eras of
geologic time?
* Which geologic era was the
“age of reptiles/dinosaurs”?
?
Which geologic era was by far
the longest?
* Which geologic era is the
“Age of mammals”?
Answer: precambrian era = longest (*cenozoic era = age of mammals) Answer: the 4 eras are precambrian, paleozoic, mesozoic, & cenozoic.
(*the mesozoic was the “age of dinosaurs/reptiles)
?
?
* Giant mosasaurs lived during which era?
570
0
65
225
Answer: Cincy fossils = paleozoic era (* mosasaurs = mesozoic era)
* C14 decays into what new element?
?
Answer: femur is upper leg bone, tibia is the bigger lower leg bone
What is the half-life of carbon-14 (C14) ?
Where is femur?
Where is tibia?
Millions of Years Ago (mya)
4600
Cincinnati fossils were formed
from animals that lived during
which era?
?
Which geologic era lasted from 4600 mya to 570 mya?
* Which geologic era lasted from 225 mya to 65 mya?
UNDECAYED ( % )
25
0
0
1
. . .
. .
2
3
4
HALF-LIVES
5
?
After 2 half-lives, what percent remains undecayed?
How many half-lives pass before 12% remain undecayed?
Why does Jack Hoerner think that
T-rex had a great sense of smell?
* What modern animal has an
“olfactory” very similar to T-rex’s?
?
?
* What is the half-life and the
decay product of Potassium-40?
Which two bones give clues about
T-rex’s running ability?
* Why does Jack Hoerner believe
T-rex was not a fast runner?
?
Answer: femur (upper leg) & tibia (lower leg) give clues about speed.
(* T-rex has longer femur than tibia....common in slower runners)
.
Answers:
2 half-lives = 25%
12% = 3 half-lives
50
What is the half-life and the
decay product of Uranium-238?
Answer: U-238 half-life = 4.6 by, decay product = Lead-206 (Pb206)
* K-40 half-life = 1.3 by, decay product = Argon 40 (Ar4 0)
Answer: C14 half-life = 5730 yrs (* C14 decays into Nitrogen-14)
75
Answers: precambrian = 4600 mya to 570mya
(* mesozoic era = 225 mya to 65 mya)
.
100
Answer: T-rex cat scan shows large olfactory (smell center of brain).
(* Vultures have similar very large olfactory...can smell 20+ miles)