Ancient Shape-Shifters: What the First Animals were Like

Fagjun | Published 2017-07-11 08:19

An artist's rendering of the shape-shifting rangeomorphs
[Photo by Jennifer Hoyal Cuthill]

If life on Earth began as microorganisms, then how did large animals like dinosaurs and blue whales come about? Scientists say that shape-shifters that appeared early in Earth's history may hold the answer.

These shape-shifting creatures are rangeomorphs. They are large organisms that can grow and change their shape by siphoning nutrients from their environment. At two meters tall, rangeomorphs can grow taller than modern humans. They lived in the ocean between 635 and 541 million years ago, during the Ediacaran period. Rangeomorphs are remarkable in that they existed during a time period in which other living things on Earth were microscopic in size.

How Shape-Shifters Thrived

Rangeomorph fossils and rendering
[Photo by Hoyal Cuthill and Conway Morris]

Scientists call the ability of rangeomorphs to shape-shift “ecophenotypic plasticity”. Organisms with ecophenotypic plasticity were able to change their size and shape through the nutrients they took from their surroundings. Their size and shape depended on what kinds of nutrients were available to them. Rangeomorphs in particular had a high degree of ecophenotypic plasticity, which enabled them to cope with the huge changes in their environment at the time.

Rangeomorphs were soft-bodied organisms that looked somewhat like ferns. They looked like they had branches that also had smaller branches, a shape that scientists call a fractal. Scientists believe there's a possibility that these shape-shifters were the very first animals on Earth. Now, scientists want to know how rangeomorphs came into existence at that point in time.

The Cambrian Explosion

Fossils are all we have left of rangeomorphs.
[Photo by Verisimilus]

There may have been sudden changes in the chemical makeup of the Earth's oceans during that period. Scientists aren't sure yet, but it's possible that an oxygen increase in the oceans may have taken place. This may be the reason behind the growth of rangeomorphs. Though the changes in their environment were dramatic, the ecophenotypic plasticity of rangeomorphs allowed them to thrive. Rangeomorphs were able to shape-shift and grow taller to reach the oxygen-rich waters just above them. Thus, their bodies shifted to an elongated shape.

Spoiler alert, though—rangeomorphs thrived only for a time. The rangeomorphs we have today are only those on fossil records. Eventually, rangeomorphs died out when the Earth underwent changes again and they were no longer able to cope. Being shape-shifters helped them survive certain changes, but not others. The so-called “Cambrian Explosion” began, during which major animal groups appeared.

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