Earth's Geological Timeline: Major Eras, Extinctions, and Evolutionary Milestones

What is the time frame of the Cenozoic Era?

From 65 million years ago (Mya) to the current day.

What significant event marked the end of the Cretaceous Period?

The Cretaceous Mass Extinction, which occurred 65 Mya.

What caused the Cretaceous Mass Extinction?

An asteroid impact that created the Chicxulub Crater, blocking sunlight and disrupting food webs.

When did the first birds appear in the fossil record?

150 million years ago (Mya) during the Jurassic Period.

What significant event occurred 250 million years ago at the end of the Permian Period?

The Permian Mass Extinction, which marked the end of the Paleozoic Era.

What was the primary cause of the Permian Mass Extinction?

Global warming due to hypervolcanic activity in Siberia.

What significant life forms appeared during the Triassic Period?

The first mammals appeared 225 million years ago.

What major evolutionary event is associated with the Cambrian Period?

The Cambrian Explosion, a rapid increase in species diversity.

What were the first multicellular animals to appear?

Phyla Porifera (sponges), Cnidaria (jellyfish), and Mollusca.

What is the significance of the Oxygen Revolution?

It allowed for the accumulation of oxygen in the atmosphere, enabling aerobic respiration and terrestrial life.

When did the first terrestrial life forms appear?

During the Ordovician Period, with the emergence of fungi, plants, and arthropods.

What does the term 'Snowball Earth' refer to?

A period when ice covered Earth from the poles to the equator, making it inhospitable.

What is the age of the first prokaryotic life forms?

Fossils of cyanobacteria date back to 3.5 billion years ago.

What is the significance of the Cambrian Explosion in evolutionary history?

It marked the first appearance of all modern animal phyla within a short geological time frame.

What are the three reasons for the Cambrian Explosion?

1. Melting of Snowball Earth, 2. Increase in oxygen levels, 3. Predator-prey interactions.

What was the first eukaryotic life form?

The simplest eukaryotes, which are protists like Amoeba and Paramecium.

What is the estimated time it took for life to evolve from single-celled to multicellular eukaryotes?

900 million years.

What is the approximate duration of each geological period?

About 50 million years, though some periods are longer or shorter.

What marked the end of the Paleozoic Era?

The Permian Mass Extinction.

What evidence supports the asteroid impact theory for the Cretaceous extinction?

The presence of the Chicxulub Crater and high levels of iridium in rocks dated to 65 Mya.

What is the significance of the first multicellular eukaryotes?

They represent the simplest forms of multicellular life on Earth.

What type of life dominated the Mesozoic Era?

Reptiles, including dinosaurs.

What major evolutionary development occurred during the Devonian Period?

The first amphibians appeared 365 million years ago.

What is the significance of the first terrestrial life forms?

They marked the transition of life from water to land.