Biodiversity and Evolution: Earth History Overview

Flashcards covering major geological periods, life origins, biological milestones, and the five major mass extinctions as detailed in the Earth History overview lecture.

Archaean

The geological eon spanning from $4.0-2.5$ billion years ago ($BYA$) involving the origin of life and the appearance of the first microfossils.

Microstromatolites

The first microfossils dating from $3.5$ billion years ago ($BYA$) which consist of photosynthetic bacteria.

Proterozoic

The eon from $2.5$ billion years ago ($BYA$) to $539$ million years ago ($MYA$) characterized by an oxidative atmosphere, glaciation periods, eukaryotes, and multicellularity.

Palaeoproterozoic

The era from $2.5-1.6$ billion years ago ($BYA$) that included the Great oxygenation event and the origin of eukaryotes around $2$ billion years ago ($BYA$).

Great oxygenation event

A massive increase in oxygen levels ($10^5$ fold) occurring roughly $2.5-1.6$ billion years ago ($BYA$), likely caused by photosynthesis from cyanobacteria.

Huronian glaciation

A mass extinction event triggered by the Great oxygenation event during the Palaeoproterozoic era.

Primary endosymbiosis

The process occurring around $2$ billion years ago ($BYA$) that led to the origin of eukaryotes.

Mesoproterozoic

The era from $1.6-1$ billion years ago ($BYA$) involving sexual reproduction, diversification of unicellular organisms, and secondary endosymbiosis.

Secondary endosymbiosis

An event in the Mesoproterozoic era that gave rise to the first glaucophytes, red algae, and green algae.

Neoproterozoic

The era from $1000-539$ million years ago ($MYA$) featuring major glaciation, the formation of the ozone layer, and the split of major animal lineages.

Snowball Earth

A condition during the Cryogenian period ($720$ million years ago) where Earth was probably almost fully covered by ice.

Ediacaran

A period around $635$ million years ago ($MYA$) providing clear fossil evidence of multicellular life forms.

Ozone layer

A protective layer formed in the Neoproterozoic that blocks UV radiation, enabling the colonisation of land.

Phanerozoic

The current eon from $539$ million years ago ($MYA$) to the present, divided into the Palaeozoic, Mesozoic, and Cenozoic eras.

Cambrian

The period from $539-487$ million years ago ($MYA$) where all modern animal phyla were represented and trilobites were abundant.

Burgess Shale

The source of many Cambrian fossils that show all major animal groups were already present during that period.

Ordovician

The period from $487-443$ million years ago ($MYA$) characterized by many invertebrates and armoured fishes.

Gnathostomes

The first jawed fishes, which appeared during the Silurian period between $443-419$ million years ago ($MYA$).

Devonian

The period from $419-359$ million years ago ($MYA$) involving the first terrestrial vertebrates (amphibians), teleosts (bony fishes), sharks, and insects.

Carboniferous

The period from $359-299$ million years ago ($MYA$) featuring the first reptiles with cleidoic eggs, winged insects, and a peak in oxygen levels.

Permian

The period from $299-252$ million years ago ($MYA$) involving the diversification of insects (the first beetles) and the separation of reptile lineages.

Triassic

The period from $252-201$ million years ago ($MYA$) characterized by the first dinosaurs, turtles, and flies.

Jurassic

The period from $201-143$ million years ago ($MYA$) where dinosaurs were the dominant terrestrial megafauna and the first mammals and birds appeared.

Cretaceous

The period from $143-66$ million years ago ($MYA$) characterized by the evolution of angiosperms and the first bees and ants.

Cenozoic

The era from $66$ million years ago ($MYA$) to now, known as the 'Age of mammals,' including the radiation of angiosperms and grasses.

Ordovician-Silurian Mass Extinction

An extinction occurring $445-440$ million years ago ($MYA$) caused by a massive ice age and sea level drop of $70-100m$.

Late Devonian Mass Extinction

An extinction occurring $375-359$ million years ago ($MYA$) caused by temperature drop and oxygen depletion in oceans.

Permian-Triassic Mass Extinction

A major extinction $252$ million years ago ($MYA$) resulting in the loss of $>90\%$ of species due to fast temperature rise.

Triassic-Jurassic Mass Extinction

An extinction $201$ million years ago ($MYA$) caused by volcanic eruptions and falling sea levels.

Cretaceous-Palaeogene Mass Extinction

An extinction occurring $66$ million years ago ($MYA$) caused by an asteroid impact, resulting in the loss of non-avian dinosaurs and ammonites.