Geological eras

the precambric eon was caracterized by

• the presence of early reptiles

• the presence of cianobacterias

• the presence of early eukaryotes such as corals, jellyfish

• the early formation of a oxidizing atmosphere

the precambric Eon was divided in 3 eras:

• Hadean era

• Arcaic era

• Jurassic era

era caracterized by heavy vocanic activity and the formation of the first continents

• Hadean era

• Arcaic era

• Proterozoic era

stromatolites are

• fossils of eukaryotes

• fossils of fish

• fossils of reptiles

• fossils of cianobacterias

Arcaic era was characterized by:

• the presence of gases such as N2, H2, CO2, SO2

• presence of cianobacterias changing the atmosphere into oxidizing atmosphere

• the formacion of oceanic basins (cuencas oceanicas)

• the early presence of trilobites

era characterized by the formation of the first continents such as Laurentia, the longest era of the precambric eon, first appereance of eukaryotes and multicellular organism such as algae, formation of the supercontinet Rodinia and a massive extinction

• Hadean era

• Arcaic era

• Proterozoic era

• Cambric era

Eon responsible of the most important changes on the planet, divided in 3 eras: era of fishes, era of reptiles and era of mammals

the phanerozoic era is composed of _____ periods, at the end of the period the formation of the supercontinent ______ took place and most of the animals at the beginning of the era were ______

• 3 -- Pannotia -- terrestrial

• 6 -- Pangea -- acuatic

a mega explosion in diversity took place in

• Devonian period

• Ordovicic period

• Pre-cambric period

what is this

• trilobites

• stromatolites

• exoskeleton