g 1402 lecture lab 12 life of the paleozoic
Post on 02-Jan-2017
213 Views
Preview:
TRANSCRIPT
Precambrian Life
Oldest fossils: 3,600
million years old
Dates are debated.
Possibly some older—
please watch the research
Stromatolites: algal mats
made by cyanobacteria
(the oldest fossils)
3
Precambrian Life
Stromatolites: algal mats
made by cyanobacteria
(the oldest fossils)
El Paso: Precambrian
stromatolites in the
Castner Marble in the
Franklin Mountains.
4
Cliff face of stromatolites
Precambrian Life
Australia:
Still living
cyanobacteria
creating
stromatolites
(Note the
shovel for
scale.)
5
6
Precambrian Life
Oldest fossils: 3,600 million years old
All Archean fossils are prokaryotes—one cell
without a nucleus
7
Precambrian Life
2,700 million years ago
First eukaryotes: one cell with a nucleus (a major evolutionary step)
Prokaryotes still dominate
Evidence of photosynthesizing cyanobacteria (start to release oxygen)
8
Precambrian Life
1,700 million years ago
Multicellular algae
900 million years ago
Multicellular worms (China) – metazoans – multicellular animals
Don’t bother to memorize these numbers.
9
Precambrian Life
Late Proterozoic animals
Ediacara Fauna (soft-bodied organisms)
Named after hills in Australia where first found
All soft-bodied animals: algae, jellyfish, worms,
strange stuff
10
Precambrian Life
Some shell fragments (580 mya)
The beginning of the Phanerozoic (from Greek for
visible life)
Cambrian—542 mya: Know this date!
hard-bodied organisms (shells)
The Cambrian Explosion! – invertebrate
fossils “suddenly” become abundant worldwide
11
Note:
Epeiric Sea -- Refers to shallow sea the covers
the continent (the mainland)
Also called epicontinental seas
12
The Paleozoic Seven Periods—Know these
Geologic Time Scale—inside front cover of lab book
Can Oscar See Down My Pants Pocket?
Cambrian (oldest)
Ordovician
Silurian
Devonian
Mississippian
Pennsylvanian
Permian (youngest)
Trichophycus Marks the base of the Cambrian
Trace fossil: a burrow
(Do NOT memorize)
13
http://www.envs.emory.edu/faculty/MARTIN/ichnology/Trichophycus.htm
14
At the beginning of the Paleozoic…
Major hard shell organisms appear—The
Cambrian Explosion
Marks the end of the Precambrian
Marks the beginning of the Phanerozoic (time scale)
Many, many soft shell organisms—these still
dominate
Marine invertebrates are dominant life forms
15
A Brief Overview of the
Paleozoic—The Sequence
Animals with skeletons appear abruptly and
widely (Exoskeletons—shells. The “Cambrian Explosion”)
Fish evolve (Cambrian—jawless fish)
Plants go ashore (Ordovician) before animals
From fish—first land animals: amphibians (give
birth in the water—e.g.: frogs) (Devonian)
16
A Brief Overview of the Paleozoic
From amphibians—reptiles (lay hard-shelled
eggs—no need to be near water to reproduce,
e.g.: alligators and crocodiles) (Pennsylvanian)
The ending—the greatest extinction in the
history of Earth (Note: This is not the
extinction of the dinosaurs.)
Paleozoic
Epeiric Seas
Do not memorize these
sea names.
Deposition.
What is going on with
the continents?
17
The Sauk Sequence
The Sauk Sea
•An epeiric sea—
covered El Paso
•A period of
deposition (Bliss
Sandstone and El
Paso Group—
limestone and
dolostone
19
The Tippecanoe
Sequence
•Late Ordovician
•Transgression—the
Tippecanoe Sea
(note mobile belts)
•More extensive
than the Sauk Sea
21
The Tippecanoe
Sequence
•Most of North
America was under
sea level
•Deposition in El
Paso of the
Montoya Group of
limestone and
dolostone (shallow
sea deposits)
22
The Kaskaskia Sequence
•Regression by late
Silurian—erosion—
unconformity
•Late Devonian to
Mississippian
•The Kaskaskia Sea
23
The Kaskaskia Sequence
•Mud rather than
limestone: black
shale deposits—the
Percha Shale
•Then limestone—
Las Cruces
Formation in El
Paso area
24
25
The Kaskaskian Regressed
Late Mississippian
Clastic deposition
El Paso: interbedded sandstone and limestone
Then: erosion and unconformity—obvious in North
America, absent in rest of the world (Rest of world
speaks of Carboniferous rather than Mississippian-
Pennsylvanian)
The Absaroka Sequence
•Late Mississippian & Early Pennsylvanian
•Small scale transgressions and regressions: cyclothems—many coal deposits
in the eastern U.S.
26
The Absaroka Sequence
•Regressed during the Permian
•Guadalupe Mountains: Permian reef deposits
•Late Permian rocks missing or redbeds (exposed to oxygen)
27
31
The Paleozoic (Cambrian)
The Earliest Organisms
with Hard Parts Appear
Proterozoic animals with calcareous tubes (define
calcareous)
Microscopic fossils with shells
Large animals (we can see them with our eyes)
with shells (exoskeletons) during Cambrian
Explosion
32
A Quick Look at Today’s
Marine Invertebrates
Pelagic—organisms that live above the sea
floor
Plankton: floaters
Nekton: swimmers
Benthonic—organisms that live on or in the sea
floor
Sessile: stay in one place
Mobile: move about
(6 words to know)
33
The Cambrian Explosion
Animals with skeletons suddenly appear (mostly
external skeletons--shells) Note: “suddenly”
occurred over millions of years
Why this occurred: still hotly debated
34
The Major Players in the Early
Paleozoic—the Cambrian
Trilobites—extinct by end of Paleozoic
Brachiopods
Archaeocyathids—reef builders
(See next slides for examples.)
Life
Trilobites
•Most common
Cambrian fossil
•Extinct by end
of Paleozoic
•Declined during
the Silurian
35
Brachiopods Still alive today.
37
Invertebrates
Bilateral symmetry
Two part shell
Top
Bottom
Example: oysters
41
Ordovician: World-wide epeiric seas—rapid radiation
and diversification of marine invertebrates
Brachiopods--First appear during the
Cambrian——bilateral symmetry
Bryozoans—twig-like fossils
Graptolites—extinct plankton (Which means?)
Arthopods (jointed foot)—lobsters, etc.
Mollusks—Clams, snails, squid, etc.
Gastropods (stomach-foot)
Cephalopods (head-foot)—straight cone or coiled in
a plane (nautilus, etc.)
45
More Invertebrates
Tabulate corals-extinct after Permian
Rugose corals—extinct after Permian
Sponges
Echinoderms (five-way radial symmetry)—
starfish, etc.
47
Paleozoic Marine Vertebrates
Chordate Phylum: all animals with full spinal
cord
Oldest chordates date from beginning of
Cambrian (invertebrates dominated, but
vertebrates present): Jawless fish
50
More Fish
Devonian (the age of fish): two groups
Bony fish
Ray finned bony fish
Lobe finned bony fish
Cartilaginous fish (discuss)—primitive sharks
60
Paleozoic Plants
Oldest plants: Middle Ordovician fossil spores (Algae are not plants.)
Land organisms first appeared late Ordovician
Plants were first on land (Why plants before
animals?)
Lots of land plants by late Paleozoic
Took a while—needed ozone layer (Why?)
61
Life Evolved
Silurian: small multicellular plants on land
First: rigid stems without roots or vascular system
Then: vascular plants with roots and leaves
Devonian: creepers, restricted to damp areas
Late Devonian: seed plants—freedom!
(no flowers until the late Mesozoic)
62
Pennsylvanian
Gymnosperms (naked seed) plants evolved (pine
trees—pine cones)
Forests develop
Glossopteris—a fern in Gondwana that Wegener
used to determine the extent of Gondwana
63
Paleozoic Land Animals
Lungs, shoulder and hip bones: crosspterygians
could crawl on land. (Remember Tiktaalik)
These fish evolved into amphibians (Late
Devonian—abundant in the Mississippian and
Pennsylvanian)
Amphibians: restricted to land/water habitat
(frogs, for example)—lay there eggs in water (no
egg shell)
Early
Pennsylvanian
One group of
amphibians
developed the
amniotic egg:
hard shell and
liquid sac for
food 64
65
These are reptiles
Lay eggs on dry land
Move away from water
Colonize land and become dominant
terrestrial vertebrates
Pelycosaurs—(Not dinosaurs)
•Pennsylvanian:
pelycosaurs
evolved
•Fin-back reptiles
(not dinosaurs)
•Go extinct by
end of Permian
66
Pely…--pelvis
This is Dimetrodon
67
More evolution
Therapsids—replaced pelycosaurs—”mammal-
like” reptiles with some temperature regulation
(these dominated)—ancestors of mammals
Root words: wild beast + arch of the skull
Thecodonts—”reptile-like” reptiles
Root words: case & teeth set in sockets
(More when we look at the Mesozoic)
68
More evolution
End of Paleozoic: 90% of all reptiles are
therapsids (ancestors of mammals)
Decline at end of Paleozoic—survivors evolve
into mammals
69
Invertebrates on Land
Arthopods (jointed foot)
Eurypterids evolve into scorpions and spiders
Insects (Devonian)
Late Paleozoic: dragonflies and cockroaches
71
The Really, Really Big Extinction (Not when the dinosaurs went extinct)
End of Paleozoic (end of Permian)
Land organisms suffered most (Why land?)
75% of amphibians extinct
80% of reptiles extinct
Land plants change significantly
50% of marine invertebrates go extinct
72
The End of the Paleozoic
Pangea forms
Biggest mass extinction ever
Lose a lot of marine life
Trilobites
Fusilinids
Graptolites
Tabulate corals
Rugose corals
73
A Key Point!!
Extinctions happen due to a change in the
environment
Late Permian—Pangea formed: only one land
mass on earth—connected: no ocean barriers
Mountains uplifted, eroded, shed clastic
material—major regressions of epeiric seas
74
The Reason for Extinction
(maybe…)
Meteorite impact (ancient crater off of Australia – much debate!)
Environmental changes occurring with the formation of Pangea
Diverse habitat disappeared
Weather patterns changed
Volcanic eruptions—A widely held view
Oxygen decrease (down to ~10%?)
(cutting edge research!—we need to watch this one)
top related