New Fossil Organism Discovered
Paleontologists have discovered a fossil of newly discovered organism from the 'Ediacara Biota' - a group of organisms that occurred in the Ediacran period of geologic time.
The discovered organism is named Plexus ricie and resembles a curving tube. Researchers said the organism resided on the Ediacaran seafloor.
Plexus ricei individuals ranged in size from 5 to 80 centimeters long and 5 to 20 millimeters wide.
The organisms are believed to be evolved around 575 million years ago and disappeared from the fossil record around 540 million years ago.
"Plexus was unlike any other fossil that we know from the Precambrian," said Mary L. Droser, a professor of paleontology, whose lab led the research, in a press release. "It was bilaterally symmetrical at a time when bilaterians-all animals other than corals and sponges-were just appearing on this planet. It appears to have been very long and flat, much like a tapeworm or modern flatworm."
"Ediacaran fossils are extremely perplexing: they don't look like any animal that is alive today, and their interrelationships are very poorly understood," said Lucas V. Joel, a former graduate student at UC Riverside and the first author of the research paper. Joel worked in Droser's lab until June 2013.
He added that during the Ediacaran there was no life on land and all they knew about for the period was still in the oceans.
"Further, there was a complete lack of any bioturbation in the oceans at that time, meaning there were few marine organisms churning up marine sediments while looking for food," he added. "Then, starting in the Cambrian period, organisms began churning up and mixing the sediment."
Researchers also said the lack of bioturbators during the Ediacaran allowed thick films of photosynthetic algal mats to accumulate on ocean floors. The same is now considered to be a very rare environment in the oceans today.
"The lack of bioturbation also created a very unique fossil preservational regime," Joel added in the press release. "When an organism died and was buried, it formed a mold of its body in the overlying sediment. As the organism decayed, sediment from beneath moved in to form a cast of the mold the organism had made in the sediment above. What this means is that the fossils we see in the field are not the exact fossils of the original organism, but instead molds and casts of its body."
Study results have been published in the Journal of Paleontology.