Meet Our Oldest Common Ancestor: A 555 Million-Year-Old Worm-Like Creature
Scientists have discovered our earliest common ancestor — and the earliest ancestor of all animal life.
The honor goes to a minuscule worm-like creature that lived on the seafloor 555 million years ago. Researchers led by geologists at the University of California (UC) Riverside have identified it as the first known bilaterian, an organism with a front and back, symmetrical sides and front and back openings with a gut in between.
"It's the oldest fossil we get with this type of complexity," UC Riverside geology professor Mary Droser said in a press release.
Bilaterians are an important piece of the evolutionary tree that branches out to include the full diversity of animal life. The new body structure allowed creatures to move forward purposefully.
The fossil was dated to the Ediacaran Period 555 million years ago, when multi-celled, complex lifeforms began to emerge, BBC News explained. But other fossils found in the "Ediacaran Biota" are not directly related to today's animals. These include Dickinsonia, organisms shaped like lily pads that have no mouth or gut, according to UC Riverside.
Geologists thought that bilaterians must have been alive during this period, but direct fossil evidence was hard to find. Researchers had thought for 15 years that these creatures were the explanation for fossilized burrows found in Ediacaran deposits in Nilpena, South Australia, but there was no definitive proof.
Then, Droser and UC Riverside doctoral graduate Scott Evans honed in on barely discernible oval impressions near the ends of the burrows. They used a three-dimensional scanner to fill in the impression and a body emerged — a grain-of-rice sized cylindrical creature about 2-7 millimeters long and about 1-2.5 millimeters wide.
"Once we had the 3D scans, we knew that we had made an important discovery," Evans said in the press release.
Scientists called the creature Ikaria wariootia and introduced it to the world in an article published in Proceedings of the National Academy of Sciences Monday. The name comes from the language of the Adnyamathanha people, an aboriginal group who live in the part of Australia where the fossil was found, CNN reported. Ikaria means "meeting place" and Warioota is the name of a local creek.
But the creature didn't live by the riverside. Instead, it spent its life burrowing in sand on the ocean floor in search of food, BBC News described.
The creature is also important for another reason. Evolutionary biologists had long predicted early bilaterians would be small and simple like Ikaria wariootia, according to the press release.
"This is what evolutionary biologists predicted," Droser said. "It's really exciting that what we have found lines up so neatly with their prediction."
- Construction Begins on Keystone XL Pipeline in Montana - EcoWatch ›
- Trump Approves Keystone XL Pipeline, Groups Vow 'The Fight Is ... ›
- Keystone XL Pipeline Construction to Forge Ahead During ... ›
EcoWatch Daily Newsletter
By Monir Ghaedi
As the COVID-19 pandemic continues to keep most of Europe on pause, the EU aims for a breakthrough in its space program. The continent is seeking more than just a self-sufficient space industry competitive with China and the U.S.; the industry must also fit into the European Green Deal.
European satellites continue to provide data on climate change.
In 2018, a team of researchers went to West Africa's Nimba Mountains in search of one critically endangered species of bat. Along the way, they ended up discovering another.
- Eek! Bat Populations Are Shrinking. Here Are A Few Ways to Help ... ›
- First Bat Removed From U.S. Endangered Species List Helps ... ›
- What We've Lost: The Species Declared Extinct in 2020 - EcoWatch ›
By Jim Palardy
As 2021 dawns, people, ecosystems, and wildlife worldwide are facing a panoply of environmental issues. In an effort to help experts and policymakers determine where they might focus research, a panel of 25 scientists and practitioners — including me — from around the globe held discussions in the fall to identify emerging issues that deserve increased attention.
Ask a Scientist: What Should the Biden Administration and Congress Do to Address the Climate Crisis?
By Elliott Negin
What a difference an election makes. Thanks to the Biden-Harris victory in November, the next administration is poised to make a 180-degree turn to again address the climate crisis.
- Biden Reaffirms Commitment to Rejoining Paris Agreement ... ›
- Joe Biden Appoints Climate Crisis Team - EcoWatch ›
- Biden Plans to Fight Climate Change in a New Way - EcoWatch ›