UNIVERSITY OF SOUTH ALABAMA
GY 112: Earth History
Lecture 34:
The Cenozoic: Overview
Instructor: Dr. Douglas W. Haywick
Last Time
The Mesozoic
A) Triassic Sedimentation
B) Jurassic Sedimentation
C) Cretaceous Sedimentation
Mesozoic Sedimentation
Triassic
•Initial opening of
Gulf of Mexico
Mesozoic Sedimentation
Early Jurassic
•Initial flooding of
Gulf of Mexico and
Northern Atlantic
Ocean
Mesozoic Sedimentation
Late Jurassic
…major transgression
and flooding of the craton
begins
•Sundance Sea
Mesozoic Sedimentation
Cretaceous
•Southern rifting in
the Atlantic Ocean
•Gulf of Mexico
stops opening
Mesozoic Sedimentation
Cretaceous
•Southern rifting in
the Atlantic Ocean
•Gulf of Mexico
stops opening
•AL Coastal Plain
sedimentation
Mesozoic Sedimentation
North
South
Only key formations are labeled
(those discussed in GY 112)
Mesozoic Sedimentation
North
South
Only key formations are labeled
(those discussed in GY 112)
Today’s Agenda
The Cenozoic
A) Cenozoic time frame
B) Climatic change (Mesozoic-Cenozoic)
C) Key Evolutionary Events
D) Deep Oceanic Currents
(Web notes 34)
Cenozoic Time Frame
Phanerozoic
Era
Years
Cenozoic
(0 to 65 MA)
Mesozoic
(65 to 245 MA)
Paleozoic
(245 to 550 MA)
Cenozoic
Cenozoic Time Frame
Period
Years
Quaternary
(1.6 to 0 MA)
Tertiary
(65 to 1.6 MA)
The Tertiary and Quaternary
periods are relicts of an early
geological classification of
time (Primary, Secondary,
Tertiary, Quaternary).
The former divisions were
soon abandoned. The latter
divisions are dropping out of
favor.
Cenozoic
Cenozoic Time Frame
Period
Years
Neogene
(24 to 0 MA)
Paleogene
(65 to 24 MA)
Some divide the Cenozoic
into two other periods
(Paleogene, Neogene).
Their time spans are more
equal in duration
Cenozoic
Cenozoic Time Frame
Period
Years
Quaternary
(1.6 to 0 MA)
Tertiary
(65 to 1.6 MA)
In GY 112, we’ll stick with
the old classification scheme,
but it isn’t going to be quite
as easy as this chart suggests
Cenozoic Time Frame
Cenozoic
Period
Epoch
Quaternary
Holocene (10,000 – 0 years)
(1.6 - 0 MA)
Pleistocene (1,600,000 – 10,000 years)
Pliocene (5.0 – 1.6 MA)
Tertiary
Miocene (24-5.0 MA)
(65-1.6
MA)
Oligocene (37 - 24 MA)
Eocene (58- 37 MA)
Paleocene (65-58 MA)
Introducing the Epochs (the
smallest common divisions
of geological time)
Mesozoic Paleogeography
• Most continents were
isolated
• Seas opened:
– South Atlantic; Gulf of
Mexico; Caribbean Sea
• Mid-Cretaceous sea
level high
– Tethys Seaway
Mesozoic Climate
• Wind belt
– Evaporite deposition
Mesozoic Climate
• High latitudes were
warm
– 50°F / 10°C
– Dinosaurs near south
pole
Mesozoic Climate
• Period of high sea
level
– Associated with rapid
sea floor spreading
– Long period without
reversal
Mesozoic Climate
• Oceans stagnated
– Epicontinental black
muds when seas spilled
over
– Normally thin oxygen
poor zone expanded
This will change in the
early Cenozoic (Late
Eocene)
Cenozoic Climate
• Oxygen isotopes
– Late Eocene cooling
• Deep sea foraminifera
Cenozoic Climate
• Temperature inferred
from leaf margins
Cenozoic Climate
Paleocene-Middle Eocene:
•No circumpolar current
Late Eocene-today:
•Circumpolar current
–Permitted development of glaciers
on Antarctica
Cenozoic Climate
Key Cenozoic Evolutionary Events
Cenozoic Life
• Recovery from
Cretaceous extinctions
– Modern life forms
– New animals
• Sharks (Megaladons in
Plio-Pleistocene)
Cenozoic Life
• Marine life
– Miocene ancestral
whales
• Sperm whale
• Baleen whales
• Dolphin
– Miocene recovery of
planktonic foraminifera
Cenozoic Life
• Sandy coasts offer
new niches
– Sand dollars evolved
from sea biscuits
• Flowering plants
expanded
– Grasses originated
Cenozoic Life
• Mammals diversified
– Most modern orders present by Early Eocene
Cenozoic Life
• Bats present by early
Eocene
Cenozoic Life
• Primates evolved in
Paleocene
– Climbing by Early
Eocene
Cenozoic Life
• Primates modernized
in Oligocene
– Monkeys
– Apelike primates
• Aegyptopithecus
Cenozoic Life
• Mammalian carnivores
evolved by midPaleogene
Cenozoic Life
• And diversified soon
after...
– Saber tooth tiger
– Bearlike dogs
– Wolflike animals
Cenozoic Life
• Earliest horses by end
of Paleocene
– Size of small dogs
Cenozoic Life
• Early Eocene
elephants
– Moeritherium
• Earliest
• Pig sized
Cenozoic Life
• Mesonychids
– Doglike
– Size of small bears
• Diatrymas
– Huge flightless birds
– Clawed feet and slicing
beaks
Cenozoic Life
• Few birds with flight
– Most waded
– No songbirds
Cenozoic Life
• Oligocene mammals
– A few horses in North
America
– Rhinoceroses
• Paraceratherium
• Largest land mammal
of all time
Cenozoic Life
• Terrestrial Life
– Grasses
– Herbs and weeds
– Requires arid climate
• Cooler climate linked to Antarctic glaciation
Cenozoic Life
• Spread of C4 grasses
– C4 plants
• Incorporate more
carbon 13 than C3
grasses
• Five times more silica
– Wears down teeth of
grazers
Cenozoic Life
• Why the spread of C4
grasses?
– Global climate change
• Aridity, not CO2, drop
• Alkenones indicate
CO2 rise
Deep Ocean
Currents
Paleocene-Middle Eocene:
•No circumpolar current
Late Eocene-today:
•Circumpolar current
–Permitted development of glaciers
on Antarctica
Cenozoic Deep Ocean Currents
Chalk Board
Messianian Salinity “Crisis”
• Geophysical analysis of the Mediterranean Sea
yielded surprising results
Messianian Salinity “Crisis”
• Geophysical analysis of the Mediterranean Sea
yielded surprising results
Salt diapirs
Messianian Salinity “Crisis”
• Geophysical analysis of the Mediterranean Sea
yielded surprising results
Today’s Homework
1. Quiz 13 (bonus 3) Thursday
2. Time Chart 3 due Thursday April 30th
Next Time
1. Cenozoic tectonics
GY 112: Earth History
Lectures 34: The Cenozoic Part 1
Instructor: Dr. Doug Haywick
dhaywick@southalabama.edu
This is a free open access lecture, but not for commercial purposes.
For personal use only.