From what little we know about them, they seem so different. Mysterious creatures that lived in the ocean half a billion years ago – headless, limbless things, seemingly foreign to us in every way.
Except they weren’t, new research suggests. In fact, the Ediacaran biota – a collection of ancient oceanic life forms that lived on Earth between 570 and 539 million years ago – is said to have shared a number of genetic similarities to modern metazoans (multicellular animals), including humans, people say. of science.
Not that the similarities border on the unusual or something.
“None of them had heads or skeletons,” says paleobiologist Mary Droser of the University of California, Riverside.
“Many of them probably looked like three-dimensional carpets on the seabed, round disks sticking together.”
Droser has something specialized in investigating strange organisms from Earth’s distant past.
A year ago, she conducted a study that identified such an Ediacaran: Ikaria wariootia, a strange, slow spot the size of a grain of rice, which could have been the oldest ancestor of all animals with symmetrical bilateral bodies.
However, not all Ediacarans necessarily have such close ties to animals today.
There are over 40 recognized species from the period – including the most famous, the ovoid Dickinsonia, and another named after President Obama – and it’s not always easy to determine where their fossilized forms should stand in the tree of life.
“These animals are so strange and so different that it’s hard to attribute them to modern categories of living organisms just by looking at them,” says Droser. “And it’s not like we can extract their DNA – we can’t.”
Without being able to directly analyze the genetic data of these creatures, researchers must manage to deduce what they can from the fossil traces that these organisms have left behind. Fortunately, those ancient prints can reveal quite a bit.
In a new study co-authored by Droser and led by first author and paleontologist Scott Evans of the Smithsonian National Museum of Natural History, the researchers looked at four representatives of the Ediacaran biota: Dickinsonia, Ikaria, in the form of a servant Kimberellaand the hemispherical blob Tribrachidium.
Based on fossil observations and what we can deduce about how these creatures moved their bodies, maintained themselves, and generally lived their lives on the ancient seabed, the researchers propose that the animals most likely contain a rudimentary form of the nervous system, supported and regulated by the same types of genetic regulatory elements still used by living animals today, including humans.
“This analysis demonstrates that genetic pathways for multicellularity, axial polarity, musculature, and a nervous system were probably present in some of these early animals,” the authors write.
“Together these traits help to better constrain the phylogenetic position of several key Ediacara taxa and inform our views on the early evolution of metazoans.”
Specifically, in the new study, the team presents a wide range of genes that could have influenced multicellularity, immunity, nerves, apoptosis (programmed cell death), axial modeling (which differentiates the sides of the body, such as the face or back and left or right), and others.
Although there is much more to learn about these truly ancient creatures, the biology that unites us over millions of years shows that they may not be as strange as they seem.
“The fact that we can say that these genes worked in something that has been missing for half a billion years is fascinating to me,” says Evans.
The findings are reported in The works of the Royal Society B.