Life on Earth has been around for billions of years and there are many theories on how it may have started. But first to the beginning of Earth. About 4.5 billion years ago Earth formed. In its earliest days, our planet looked very different. Instead of the blue,green and brown planet that we’re familiar with, Earth was a ball of magma, it was constantly bombarded with comets and meteors and was always exposed to harmful UV rays. About 4 billion years ago the Earth cooled down due to solidification of its outer layers, the reduction of greenhouse gases in Earth’s atmosphere and a stop to the constant bombardment of meteors.
As many know life first started in the ocean, likely around hydrothermal vents, because of the nutrient rich water that surrounded them. In the deep waters the life wasn’t very noticeable, the life forms that swam around were microscopic single celled organisms. Among those single cells was the F.U.C.A (the First Universal Common Ancestor) all life on earth evolved from this tiny organism that lived 4-3.7 billion years ago. For a few billion years these small organisms were the only life on Earth. Single celled organisms could carry out all life functions in one cell and had no need to be multicellular.
About 3 billion years later the first multicellular organisms appeared, called Ediacarans, they were flat and soft bodied. The first modern animal,well their fossils, were dated back 560 mya (million years ago). This animal is the Sea Sponge. After the Sea Sponge evolved there was an explosion of new life forms, called the Cambrian Explosion. This “Explosion” marks the start of the Paleozoic era (541-252 mya). The Paleozoic marked the first major period of life on Earth. Life was experimenting and some wacky animals evolved, some had 5 eyes (Opabinia Regalis), some looked like plants, and some had clawed proboscis. An exciting life form, Fish evolved in this time period with 2 main types, Jawed and Jawless. A very exciting life form were the Sea Scorpions that patrolled the seas, with their shelled body and large claws, their arthropod brethren the Trilobites scurried a long the seafloor. A large percentage of life were early Cnidarians and Mollusks. A much Larger percentage of mollusks had shells back then like the mighty Ednoceras with shells 20 feet in length. Even early shark-like animals could have been spotted back then. All of those amazing creatures lived in the Ocean, but what was happening on land?
During the Ordovician period the first land plants evolved, they were very similar to mosses today. Later in the Devonian period Arthropods and other vertebrates evolved to live on land. Some cool animals that evolved on land were: Dimetrodon, Gorgonops, Moschops and Anapsids. The Paleozoic was truly a time to be alive.
All good things must come to an end though, the mass extinction that ended the Paleozoic is the worst mass extinction event that life has ever seen. The Permian-Triassic extinction wiped out 90% of ocean life and 70% of land vertebrates. This event, Known as the Great Dying, was likely caused by massive volcanic eruptions in Siberia which caused ocean acidification, oxygen depletion, global warming and more. Many call Dinosaurs the coolest animals, and they are awesome, but the creatures of the Paleozoic should never be forgotten as life’s coolest creatures.
Related Stories:
https://news.uchicago.edu/explainer/origin-life-earth-explained
https://cneos.jpl.nasa.gov/about/life_on_earth.html
https://www.nationalgeographic.com/science/article/early-life-earth-theories
https://researchoutreach.org/articles/origin-life-conditions-sparked-life-earth/
Take Action:
How to volunteer to help preserve life on earth:
https://www.fws.gov/volunteer-opportunity
https://www.nature.org/en-us/get-involved/how-to-help/volunteer/
Learn about biodiversity and it’s importance:
https://www.worldwildlife.org/pages/what-is-biodiversity
Buy a beautifully illustrated book explaining many animals of the Paleozoic:
https://www.barnesandnoble.com/w/ocean-renegades-abby-howard/1127947289
