New research shows, the earliest multicellular organisms may have lacked arms, heads, or legs, yet pieces of them remain inside of us today.
As per UC Riverside research, 555-million-year-old oceanic animals from the Ediacaran period share genes with today’s animals, including human beings
Mary Droser, a geology professor at UC Riverside said, “None of them had heads or skeletons. Many of them probably looked like three-dimensional bathmats on the seafloor, round discs that stuck up.”
“These animals are so different and so weird, it is difficult to assign them to modern categories of living organisms just by looking at them, & it is not like we can extract their DNA — we can’t.”
Although, well-preserved fossil records have permitted Droser and the study’s first author, recent UC Riverside doctoral graduate Scott Evans, to link the animals’ appearance & likely behaviors to genetic analysis of presently living things.
Their study on these links has been recently published — in the journal Proceedings of the Royal Society B.
For their analysis, the scientists considered 4 animals representative of the more than 40 recognized species that have been distinguished from the Ediacaran era. These animals ranged in size from a couple of millimeters to almost a meter in length.
Kimberella was teardrop-shaped animals with one broad, rounded end and one narrow end that probably scraped the seafloor for food with a proboscis. Further, they could move around utilizing a “muscular foot” like snails today.
The research included flat, oval-shaped Dickinsonia with a series of raised bands on their surface, and Tribrachidium, who spent their lives immobilized at the lower part of the ocean.
Likewise analyzed were Ikaria, animals recently found by a team including Evans and Droser. They were about the size and shape of a grain of rice, and represent the first bilaterians organisms with a front, back, and openings at either end connected by a gut.
Evans said it is likely Ikaria had mouths, however, those were not preserved in the fossil records, and they crawled through organic matter “eating as they went.”
Each of the 4 animals was multicellular, with cells of various types. Most had symmetry on their left and right sides, as well as noncentralized nervous systems and musculature.
Moreover, they seem to have been able to repair damaged body parts through a process known as apoptosis. Similar, genes involved are key elements of human immune systems, which help to eliminate virus-infected and pre-cancerous cells.
These animals probably had the genetic parts responsible for heads and the sensory organs typically discovered there. Although, the complexity of interaction between these genes that would give rise to such features hadn’t yet been accomplished.
“The fact that we can say these genes were operating in something that is been extinct for half a billion years is fascinating to me,” Evans said.
Going ahead, the team is planning to explore muscle development and functional studies to further understand early animal evolution.
“Our work is a way to put these animals on the tree of life, in some respects,” Droser said. “And show they’re genetically linked to modern animals, and to us.”