Image courtesy Anthony Prave, University of St. Andrews
Published February 7, 2012
Microscopic, sponge-like African fossils could be the earliest known animals—and possibly our earliest evolutionary ancestors, scientists say.
(Related: "Earliest Animals Were Sea Sponges, Fossils Hint.")
The creature, Otavia antiqua, was found in 760-million-year-old rock in Namibia and was as tiny as it may be important.
"The fossils are small, about the size of a grain of sand, and we have found many hundreds of them," said study leader Anthony Prave, a geologist at the University of St. Andrews in the U.K.
"In fact, when we look at thin sections of the rocks, certain samples would likely yield thousands of specimens. Thus, it is possible that the organisms were very abundant."
From these tiny "sponges" sprang very big things, the authors suggest. As possibly the first muticellular animals, Otavia could well be the forerunner of dinosaurs, humans-basically everything we think of as "animal."
(Related: "405-Year-Old Clam Called Longest-Lived Animal.")
Oldest Animal Built to Last?
Prior to the new discovery, the previous earliest known "metazoan"—animals with cells differentiated into tissues and organs—was another primitive sponge, dated to about 650 million years ago.
Based on where the new fossils were found, Prave and his colleagues think Otavia lived in calm waters, including lagoons and other shallow environments.
The team thinks Otavia fed on algae and bacteria, which the animal drew through pores on its tubelike body into a central space. There the food was digested and absorbed directly into Otavia's cells.
(Also see "Was The Humble Sponge Earth's First Animal?")
The simple setup seems to have worked.
The fossil record indicates Otavia survived at least two long-term, severe cold snaps known as "snowball Earth" events, when the planet was almost completely covered in ice.
Despite such wild environmental swings, "the oldest and youngest Otavia fossils all have the same quasi-ovid form, with large openings leading from the exterior," Prave said in an email.
In short, the animals didn't evolve much, he said—suggesting that, at least for its roughly 200 million years of existence, Otavia was built to last.
The new oldest-animal study is detailed in the current issue of the South African Journal of Science.
Latest News
Trending News
-
Mystery of Deadly Volcanic Eruption Solved?
Using ice cores, geochemistry, tree rings, and ancient texts, scientists discover which volcano erupted in the 13th century with worldwide effects.
-
First Cloud Map of Exoplanet
For the first time, astronomers can forecast cloudy skies on a distant exoplanet.
-
First Face Found—On a Fish
The extinct animal's face structure could help explain how vertebrates, including people, evolved our distinctive look.
Advertisement
Celebrating 125 Years
-
Explorer Moment: America by Night
Annie Agnone discovers that when the sun sets, the monks rise.
-
From the Stacks: Meow Mix, 1938
Not all the animals National Geographic has covered have been wild ones.
News Blogs
- Will the Big Cats Survive the Free-Roaming Domestic Cats in the Sundarbans & Elsewhere?
- Of Kangaroos and Caribou
- ‘Purrfect’ Match: ‘Cat Whisperer’ Mieshelle Nagelschneider & ‘Cat Daddy’ Jackson Galaxy Join Forces for Stray Cat Alliance
- Despite Shutdown NASA Planetary Probes On the Job
- Beaver Butts Emit Goo Used for Vanilla Flavoring
Connect With Nat Geo
