eras & evolution

macroevolution

major changes in life above the species level in earth’s history

origin of first cells

~3.5 bya

oldest cell fossils

prokaryotes

stromatolite formations

mats of prokaryotes (fossils)

adaptive radiation

offspring from original organism get blown off to different islands/environments

how did major new forms arise?

1. “new” form results from change in function, then form

2. development & evolution

3. heterochrony

exaptation

adapted to different use

developmental genes

control development of multicellular organisms

regulatory genes

control when, where, & which genes are expressed

heterochrony

evolutionary charge in form due to change in rate or timing of developmental events

paedomorphosis

a sexually mature adult w/ juvenile feature due to one gene producing a change in timing

homeotic (Hox) genes

genes that tell the organism during development what the body plan is

hadean eon

planet formed 4.6 bya

archean eon

crust cooled, solidified 3.8 bya ago

eukaryotic life began

2.1 bya

oxygen revolution

~2.7-2.5 bya

how did the oxygen revolution come to be

photosynthesis by prokaryotes made seas & atmosphere O₂ - rich

proterozoic eon

2.5 bya

first multicellular life (algae & animals)

~600 mya

paleozoic era

535 mya

what happened during the paleozoic era

cambrian explosion of animal diversity

what ended the paleozoic era

permian mass extinction

mesozoic era

251 mya

mesozoic breakup of pangea & continental drift directly affected

• climate change

• allopatric speciation

• species distribution

what ended the mesozoic era

cretaceous mass extinction

when did the dinosaurs die

cenozoic era

cenozoic era

65 mya

first humans

~200,000 years ago