ELS-Q2-L1-Evolving Concept of Life Based on Emerging Pieces.pptx

Evolving Concept of Life

1. Evolving Concept of Life Based on Emerging Pieces of Evidence

2. Historical Development of the Concepts of Life

3. Have you been curious of when and where did life possibly start on Earth? During the 1800s, geologists and the naturalists found several forms of physical evidence that confirmed that Earth is very old. The evidence includes: fossils of ancient sea life on dry land far from oceans, this supported the idea that the Earth changed over time and some dry land today was once covered by oceans; the many layers of rock allowed the people to realize that rock layers represent the order in which rocks and fossils appeared, thus they were able to trace the history of Earth and life on Earth; lastly, the indications that volcanic eruptions, earthquakes and erosion that happened long ago shaped much of the Earth’s surface and supported the idea of an older Earth. This module will help you understand the historical development of the concept of life based on emerging pieces of evidence. This will trace back the events, processes, and living organisms existed on earth from the earliest time to present. Introduction

4. Evidence of Life Hadean (Early Earth Development) Archean (Period of Appearance of First Prokaryotes) Proterozoic Eon (Period of Appearance of the First Eukaryote) Paleozoic Era (Dominance of Appearance of Trilobites) Mesozoic Era ( Dominance of Dinosaurs) Cenozoic Era (Recent Life)

5. HADEAN (Early Earth Development) The Hadean was originally defined as the birth of the planet occurring 4.0 billion years ago and preceding the existence of many rocks and life forms.  However, geologists have dated minerals at 4.4 billion years, with evidence that liquid water was present. There is possibly even evidence of life existing over 4.0 billion years ago. However, the most reliable record for early life, the microfossil record, starts at 3.5 billion years ago.

6. HADEAN (Early Earth Development)

7. ARCHEAN (Period of Appearance of First Prokaryotes) Fossil evidence of the earliest primitive life-forms—prokaryotic microbes from the domain called Archaea and bacteria—appears in rocks about 3.5–3.7 billion years old; however, the presence of ancient fragments of graphite (which may have been produced by microbes) suggest that life could have emerged sometime before 3.95 billion years ago.

8. ARCHEAN (Period of Appearance of First Prokaryotes)

9. Proterozoic Eon (Period of Appearance of the First Eukaryote) The Proterozoic Eon extended from 2.5 billion to 541 million years ago and is often divided into the Paleoproterozoic (2.5 billion to 1.6 billion years ago), the Mesoproterozoic (1.6 billion to 1 billion years ago), and the Neoproterozoic (1 billion to 541 million years ago) eras. Organisms that lived during the Proterozoic eon include single-celled anaerobic prokaryotes, which were replaced by photosynthetic prokaryotes like cyanobacteria.

10. Proterozoic Eon (Period of Appearance of the First Eukaryote)

11. Paleozoic Era (Dominance of Appearance of Trilobites) Paleozoic Era, major interval of geologic time that began 538.8 million years ago with the Cambrian explosion, an extraordinary diversification of marine animals, and ended about 252 million years ago with the end-Permian extinction, the greatest extinction event in Earth history.

12. Paleozoic Era (Dominance of Appearance of Trilobites)

13. Major Divisions of the Paleozoic Era (oldest to youngest) Cambrian (538.8 million to 485.4 million years ago) Ordovician (485.4 million to 443.8 million years ago) Silurian (443.8 million to 419.2 million years ago) Devonian (419.2 million to 358.9 million years ago) Carboniferous (358.9 million to 298.9 million years ago) Permian (298.9 million to 252.2 million years ago) periods. * The Paleozoic takes its name from the Greek word for ancient life .

14. Mesozoic Era (Dominance of Dinosaurs)

15. Cenozoic Era (Recent Life) It is third of the major eras of Earth’s history, beginning about 66 million years ago and extending to the present. It is generally divided into three periods: the Paleogene (66 million to 23 million years ago), the Neogene (23 million to 2.6 million years ago), and the Quaternary (2.6 million years ago to the present); however, the era has been traditionally divided into the Tertiary and Quaternary periods.

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