history of life part 3. proterozoic eon 2.5 bya – 543 mya stable continents first appear most life...
TRANSCRIPT
History of Life Part 3
Proterozoic Eon2.5 bya – 543 mya
stable continents first appear
Most life are Bacteria and Archaeans
first evidence of oxygen build-up in the atmosphere
This global catastrophe spelled doom for many bacterial groups &
made possible the explosion of eukaryotic forms.
EndosymbiosisWhat does it mean?
The rise of Eukarya 1.8 bya
Endo = withinsym = togetherbiosis = lifeEndosymbiosis = organisms of a different species living together, with one of the organisms living within the other
Symbiosis between different species of eubacteria&
between archeabacteria and eubacteria
Prokaryotes lead to Eukaryotes
Endosymbiosis Increases Organism Complexity
Croanoflagelado:-last unicellular ancestor of all eukaryotes-Characteristics similar to modern protista
800 mya: 1st-multicellular organism Sphaeroeca, a colony of choanoflagellates ~230 individuals cooperatively linked protists
850 MYA First Fungi
the fossil on right are fungal filaments resemble living filaments of common Candida species.
the fossil at right has preserved the perithecium with spores used for reproduction.
Amber fossils
760 MYA-First Animal
Otavia antiqua
-a sea spongue
Typical day in a late PreCambrian sea…
Trilobites: the 1st exoskeletons.
Finally the ocean is full of animals with hard parts… by the early Paleozoic there are lots of animals that can form fossils.
Cambrian Explosion:
~570mya- 500mya
Cambrian Explosion: A sudden explosion of complex, multicellular life at the beginning of the Paleozoic
Many of these early animals looked very strange, unlike any animals we find on Earth today.
Opibinia… 1st macroscopic predator
Most of the major phyla originated over several million years during the early Paleozoic…
520 mya Pikaia: 1st Chordate
Typical day in late PreCambrian sea…
Jawless Fish•Earliest Fish 500 mya
Armored Fish
Lobed Finned Fish
Plants Move Onto Land
480 MYA- First Land Plant
The cryptospores are the oldest land plant fossils found.
Petrified fossils
Animals Move Onto Land
Fish to Amphibian
Tiktaalik: fish-amphibian transition fossil
370 mya: Amphibians
~310 mya 1st REPTILES
first animals with backbones able to live on dry land
Ex Thecodont
Earliest DinosaurEoraptor
•230 mya
•Argentina
•3 ft long
•10 lbs
•Carnivor
•Bipedial
“dawn theif”
How is a dinosaur different from a reptile?
Flying ReptilesAppeared ~ 230mya, around the same time as dinosaurs.
They were the first vertebrates to fly.
Georgia
Eoraptor site
Reptiles to Mammals
Earliest MammalMegazostrodon
• found in Africa
•~ 220 mya
•4-5 inches long
•Carnivore
•Laid eggs
mega-large, zostros-girdle odon-tooth
Reptiles to Birds
Feathers ?…
most small theropod dinosaurs were covered in feathers.
Earliest BirdArchaeopteryx
“Ancient wing”
~150 mya
The late Cretaceous was a time of intense volcanic activity.
For many millions of years the atmosphere was modified by the release of volcanic gases and ash.
Major Extinction Event•65 mya
•65% all species become extinct, including all non-avian dinosaurs
•Worse for large animals
•Marked the end of the Mesozoic
Impact at Chixulub in Yuccatan Peninsula
Post Ice Age: Large Mammals
Ground Sloth: 20 mya
175,000 yr ago- Homo sapiens
1.8 MYA- Home erectus
first to travel long distances & use fire
2.5 MYA- Homo habilisFirst tool user
3.9 MYA- Australopithecus
afarensis
First bipedalism