Precambrian Eukaryotes
Acritarchs
Ediacaran
Vendian
Acritarchs
Cysts of unicellular eukaroytes,
perhaps algae or egg cases of
multicellular orgs.
1800 my through Devonian
Ediacaran
• 600 my-545 my
• Soft-bodied
• Many organisms of
uncertain affinity
Possible annelids,
cnidarians (coral
relatives)
Probable cnidarian
Possible mollusc?
Total mysteries
Vendian
• “little shellies”
• Right at Cambrian
boundary
Cambrian
Trilobites:
Extinct arthropods
(like lobsters or
shrimp but with
calcite skeleton)
Lingulate brachiopods
Strange
echinoderms
Sponge reef
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•
•
•
•
Middle Cambrian
Excellent preservation of soft-bodied orgs.
5 kinds of arthropods (only 3 kinds today)
First vertebrate
Mysterious critters
Burgess
Shale
Cambrian
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•
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•
Smallish
Skeletons (if any) of phosphate or thin CaCO3
Live on or near ocean floor
Sponges, trilobites, early molluscs, echinoderms, lingulate
brachiopods
Ordovician
Brachiopods
(articulate)
Bryozoans
Crinoids (echinoderms)
Cephalopods
Corals
Graptolites
Ordovician invertebrates
• More robust skeletons
• Calcite skeletons
• Taller, deeper (take up more ecological
space)
• The Paleozoic fauna appears:
rhynchenelliform brachiopods, bryozoans,
crinoids/blastoids, primitive cephalopods,
graptolites, rugose/tabulate corals
Middle-Late
Paleozoic
Middle-Late Paleozoic
• Increasing height, increasing depth
• Increasing diversity
• New organisms
– Eurypterids (giant sea scorpions)
• Fish/amphibians
Eurypterid
Fish
Jawless (bony plates on outside)
Ostracoderms
Armored:
Acanthodians & Placoderms
Chondrichthyes:
Osteichthyes:
Sarcopterygian: Lobe-finned fish
Forerunners of quadrapeds
Paleozoic What if…
• You were at a
Paleozoic banquet and
were offered these
creatures to eat:
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–
–
–
Brachiopod
Bryozoan
Crinoid
Trilobite
Which one would you
rather eat? Why?
• You were running the
Paleozoic Ultimate Fighter
show, and you had to
design matchups between
different Paleozoic
creatures. Organize at
least two matchups
between two different
kinds of creatures off the
list. Who would be good
opponents to match up? In
each case, who would win
and why?
Mesozoic Life
• Oceans - a whole new crew
• The Modern Fauna
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Mollusks
Crustaceans
Echinoids
Fish
Bivalves
Molluscs
Gastropods
Crustaceans
Echinoids
Mesozoic Life
• Oceans - a whole new crew
• The Modern Fauna
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–
–
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Mollusks
Crustaceans
Echinoids
Fish
• Plus marine reptiles and ammonites
Marine reptiles
Ammonites
Cenozoic Oceans
• Like Mesozoic: Modern Fauna
• Minus marine reptiles and ammonites
• Plus whales and marine mammals
Evolution of Tetrapods
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•
•
•
Arise from sarcopterygians (lobe-finned fish)
Amphibianish creatures
Reptiles (to birds)
Mammals
Tiktaalik - recent
transitional find
Amphibians
Adaptations for life on land
•
•
•
•
Breathe!
Locomotion
Avoid dessication
Reproduction - amniotic egg allows longer
development (no swimming larvae)
– Leathery covering or eggshell
– Larger size of egg
– Larger yolk
Adaptations for life on land:
plants
• Avoid dessication – thicker outsides
• Reproduction –
– Fancy fertilization methods, seeds
– Marine plants release gametes into water
• More complicated dispersal mechanisms for
young
Reptiles
• Anapsids: turtles and their ancestors
• Synapsids: pre-mammals & mammals
Synapsids
Therapsids:
immediate
forerunners of
mammals
Reptiles
• Anapsids: turtles and their ancestors
• Synapsids: pre-mammals & mammals
• Diapsids: Rest of reptiles
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Marine reptiles
Snakes, lizards
Pterosaurs
Crocodilians
Dinosaurs and birds
Diapsids
Pterosaurs
Crocodiles
Marine reptiles
Marine reptiles
Dinosaurs
Diapsids
Birds
What were dinosaurs like?
• At your table, address one of these
questions:
– How did dinosaurs stand? Were they capable
of fast movement?
– Were dinosaurs social animals?
– Were dinos warm-blooded?
• How do you know?
What were dinosaurs like?
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Stood erect, not sprawling
Some fast-moving
Social behavior
Maybe warm blooded
Brontosaurus, 1953
Apatosaurus, 2007
Bone strength of ceratopsians could sustain a 35mph gallop
T. rex had weak leg bones, delicate skull:
Probably walking, not running
Maybe scavenger?
Maternal care
Maiasaurs built nests in a large nesting colony, each a mom’s
length apart.
Nests have no broken egg shells in them, so mom cleaned them out.
Babies may have been incapable of walking, like baby birds, so
required care
Herding
Bone beds may represent mass mortality of a herd for example, trying to ford a river in flood, just like
caribou and wildebeest disasters of recent years.
Trackways
Some trackways have little footprints on the inside,
suggesting a herd structure like elephants, where the
babies are protected by the adults on the outside
Pack Hunting
Popular idea, not much evidence:
•One specimen of multiple raptors with prey
•Large optic lobes, used in reptiles for higher brain functions
Warm-bloodedness
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Predator-prey ratios
Thermal inertia
Haversian canals
O-18 isotopic ratio
Dino bone
Tortoise bone
O-18 to O-16 ratio varies
with:
•Season
•Internal temperature
Cold blooded animals have
growth rings and large O-18
variability.
Warm-blooded animals have
no growth rings, uniform O18 levels