New Model Reveals Life and Death of One of Earth's Earliest Animals

A new 3-D model created by researchers at the University of Cambridge reveals how some of Earth's earliest animals lived and died, a new study describes.

A bizarre group of uniquely-shaped organisms called rangeomorphs may have been some of the earliest animals to appear on Earth, living in the oceans around 575 million years ago. Until now, not much was known about the evolution and extinction of these mysterious "proto animals."

These creatures are described in the journal Proceedings of the National Academy of Sciences.

Rangeomorphs - typically 10 centimeters high - lived during the Ediacaran period that ended 541 million years ago. It was during this time that the Cambrian Explosion began - a period of rapid evolution when most major animal groups first emerged and competition for nutrients increased dramatically.

Rangeomorphs have often been considered a "failed experiment" of evolution since they died out so quickly after the start of the Cambrian Explosion, but researchers show with their new model that these strange ocean dwellers were once very successful.

"These creatures were remarkably well-adapted to their environment, as the oceans at the time were high in nutrients and low in competition," lead author Dr. Jennifer Hoyal Cuthill of Cambridge's Department of Earth Sciences, said in a university news release. "Mathematically speaking, they filled their space in a nearly perfect way."

These early Earth inhabitant also almost completely filled the space surrounding them, with a massive total surface area. This made them very efficient feeders that were able to extract the maximum amount of nutrients from the ocean water.

Cuthill and her team examined rangeomorph fossils from a number of locations worldwide, and used them to create the first computer reconstructions of the development and 3-D structure of these organisms.

Rangeomorphs were unlike any modern organism, which has made it difficult to determine how they fed, grew or reproduced, and therefore difficult to link them to any particular modern group. And despite the fact that they look like plants, researchers confirm that they are actually just rather odd-looking animals.

Unfortunately for rangeomorphs, as the Earth moved farther into the Cambrian period, they became "sitting ducks." They couldn't defend themselves against predators that were starting to evolve, and the oceans' changing chemical composition meant that they could no longer get the nutrients they required to feed - wiping them out completely.