From what little we know about them, they look so different. Mysterious creatures that lived in the ocean half a billion years ago – endless, boundless, seemingly alien to us in every way.
But they didn’t, new research suggests. In fact, the biota Ediacaran – a collection of ancient oceanic life forms that inhabited the Earth between 570 and 539 million years ago – would have shared several genetic similarities with modern day metazoans (multi- sexual) includes humans, scientists say.
Not that the reactions end on the uncanny, or anything.
“None of them had heads or skeletons,” explained palaeobiologist Mary Droser of the University of California, Riverside.
“Many of them may have looked like three-dimensional baths on the seabed, round discs that stood up.”
Droser has something special in studying strange organisms from Earth’s past.
A year ago, she led a study that named one Ediacaran as: Ikaria cosgotia, a strange, slow blob about the size of a rice grain, which may have been the earliest ancestor of all animals with bilateral symmetrical bodies.
But not all Ediacarans are as closely related to animals today, however.
More than 40 species have been identified since then – including the most famous, the ovoid Dickinsonia, and another named after President Obama – and it is not always easy to determine where their fossil forms should sit in the tree of life.
“These animals are so weird and so different, it’s hard to assign them to modern categories of organisms just by looking at them,” Droser says. “And it’s not how it can be. to extract their DNA – we can’t. “
Unable to personally analyze the genetic data of these creatures, researchers have to do it by finding as much as they can from the trace fossils left by these organisms. Fortunately, these old prints can largely appear.
In a new study co-authored by Droser and led by first author and palaeontologist Scott Evans of the Smithsonian National Museum of Natural History, researchers looked at four representatives from the Ediacaran biota: Dickinsonia, Ikaria, the snail Kimberella, and the hemispherical blob Tribrachidium.
Based on ideas about the fossils and what we can find out about how these creatures may have moved their bodies, sustained themselves, and usually lived their lives on the ancient seabed, the researchers suggest that the animals would have a basic form of nervous system, supported and governed by the same types of genetic regulatory elements that are still used by living animals. today, involving people.
“This analysis shows that the genetic pathways for heterosexuality, axial polarity, musculature, and nervous system tended to be present in some of these early animals,” the authors write.
“Together these symptoms help limit the phylogenetic situation of several major Ediacara taxa and inform our observations of early metazoan evolution.”
In particular, in the new study the team uncovers a wide range of genes that may have affected heterogeneity, immunity, nerves, apoptosis (programmed cell death), axial patterning (a differentiates body aspects, such as front or back and left or right), and more.
While much remains to be learned about these truly ancient creatures, the biology that unites us over millions of years shows that they may not be as strange as they used to be.
“The fact that we can say that these genes worked in something that has been extinct for half a billion years is interesting to me,” Evans says.
The results are reported in Proceedings of the Royal Society B..