First Animals on Earth?

As a kid, you might’ve thought that dinosaurs were the first animals on Earth. Even though they existed millions of eons ago, they were far from the first animals. In fact, some of the earliest known animals go back way earlier — to the Vendian biota of about 560 million years ago. Even though these may not be the first animals, their fossils give us a key insight of the early beginnings of animal life, and a window into millions of years before the Cambrian Explosion. Some scientists actually say, by analyzing DNA, that the first animal life may have sprouted around 610 million years ago, although this is simply an indecisive estimate. Some fossils have withstood 560 million years of tectonic activity, erosion, weathering, and other geologic phenomena to show their details today. These are known as the Ediacaran fauna, named after the Hills of Ediacara in Australia where they are found.

THE EARTH – 560 M.Y.A.

Think of the Earth today. Animals inhabit the sea, as well as land. Animals have diversified to a great extent. To get a picture of this diversification, compare yourself to our Cnidarian friend, the jellyfish (vaguely enough for general audiences). Can you think of anything similar between yourself and the jellyfish? There’s not much in common. Symmetry? Scratch that. We’re bilaterally symmetrical, while jellyfish are radially symettrical. Pneumatophores? Eh… I don’t think I have too many stinging cells on my body. But, you get the point. Now, I must tell you, most biologists believe that all animals have a common ancestor, or an ancestor that all animals share. Scientists do not know when this theoretical common ancestor existed, or what it even is. All we know is that by 560 million years ago, animal life had already diversified into a collection of soft-bodied invertibrates. There would be no such thing as land-going life for some millions of years from that point, so all life resided in the sea. Here is a list of 10 Ediacaran fossils:

Cyclomedusa – Probably the most commonly found Ediacaran fossil. Cyclomedusa also comes in various shapes and sizes, ranging from a few millimeters up to approximately a meter in diameter. Originally thought to be a planktonic Cnidarian, it is now considered to have been a benthic, or bottom dwelling animal, similar to an anemone or sea pen (although probably not a Hydroid).

Charnia – Reaching a maximum size of 1 meter in length, Charnia is a giant of Vendian life. Charnia almost has the appearance of a type of long algae with a disc-shaped anchor at its bottom, but most researchers place Charnia with the Sea Pens, a type of colonial Hydroids.