Headless sea creatures that looked like leaves were living on Earth over half a billion years ago. Although they looked nothing like humans, some of the most important genes of humans may be old relics from these long-lost creatures from the Ediacaran era from 555 million years ago.

According to Live Science, these primitive animals carry genes that code for body symmetry, sensory organs, and the immune system that can still be found in modern humans today.

 Genes Of A Half-Billion-Year-Old Sea Monsters Were Surprisingly Similar to Humans
(Photo: Wikimedia Commons)
3D rendering of Fractofusus misrai - an orgaNism from the Ediacaran period that lived 570 MYA. It comes from the Avalon assemblage of Mistaken Point, Newfoundland, Canada. Fractofusus is depicted here being surrounded by its young and connected to them with stolon-like filaments.

Animals in the Ediacaran Era

Charles Darwin and most paleontologists believed that the oldest animal fossils were of trilobites and brachiopods of the Cambrian Period that can be traced back over half a billion years ago, according to UCMP Berkeley.

But many scientists believe that simpler life forms have existed even before this era but have left no fossils. Some even believed that the Cambrian fossils represent the time of God's creation or that it is the first deposits laid down after the great biblical flood.

But animals in the Ediacaran era were flat, bottom-feeding ocean dwellers that were truly out of this world in appearance. According to a previous report of Live Science, they look more like leaves that scientists debated for many years if they were, in fact, animals.

 Most of these creatures were two steps advance of sponges in which they had nerves and guts, and they represent a huge evolutionary leap as they were the first multicellular animals to exist.

Scientists find it challenging to classify them in the tree of life, so they examined fossils from four genera representing the diversity of over 40 known Ediacaran species from the fossil sites in the Australian Outback.

These four creatures from the Ediacaran era showed that they are not as different as modern animals, even though they do not have heads and legs. These animals had some of the basic features that still exist today, like being symmetrical from left to right and having segmented bodies.

The presence of these developmental genes in these creatures suggests that many of the most important genes present in modern animals were also found in ancient animals, such as symmetry and body segmentation.

Developmental biologists have long understood the genetic elements that are responsible for animals having a front and a back, or a left and a right. This means that Ediacaran animals have similar characteristics that are controlled by the same genes as those found in modern animals.

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Genetic Scaffolding in Animals With Symmetrical Bodies

The study, entitled "Developmental processes in Ediacaramacrofossils" and published in the journal Proceedings of the Royal Society B, predicted that several genes are responsible for more complex traits that were likely hidden as well in the genes of Ediacaran animals.

Animals and humans have regulatory genes that tell other genes what to do, such as dictating which body segments become heads and feet. This is the same genetic scaffolding that all animals with symmetrical bodies have.

"The fact that we can say these genes were operating in something that's been extinct for half a billion years is fascinating to me," Scott Evans, a post-doctoral researcher at Virginia Tech, said.

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