Cambridge University researchers revealed three-dimensional reconstructions of some of the earliest animals on Earth.
The findings, reported in the journal Proceedings of the National Academy of Sciences of the United States of America, answers questions about the existence and extinction of these animals.
The animals, called rangeomorphs, were suited to ocean conditions 575 million years ago. They existed at a time when most life was microscopic. These animals were typically about ten centimeters high, but some were as tall as two meters.
"We know that rangeomorphs lived too deep in the ocean for them to get their energy through photosynthesis as plants do," study leader Doctor Jennifer Hoyal Cuthill, of Cambridge's Department of Earth Sciences.
They most likely absorbed nutrients from their surroundings directly through the surface of their bodies in a process that would be extremely difficult for modern day animals to live on.
"It would be difficult in the modern world for such large animals to survive only on dissolved nutrients," Cuthill said.
The researchers examined rangeomorph fossils from locations across the globe in order to gather enough information to perform the study.
"These creatures were remarkably well-adapted to their environment, as the oceans at the time were high in nutrients and low in competition," Cuthill said. "Mathematically speaking, they filled their space in a nearly perfect way."
About 545 million years ago the ocean's conditions changed dramatically after the Cambrian Explosion; this is when most major animal groups made their first appearances and participated in a rigorous competition for nutrients.
Rangeomorphs have been called the "failed experiment" of evolution because they died out so quickly following the Cambrian explosion, but this new experiment brings back some of their credibility by showing how successful they were in their prime.
