An international team of paleontologists has discovered fossil organisms, which they believe are the first animals that lived on Earth.
Fossilized Otavia antique from northern Namibia (Dr. Bob Brain et al)
The paper, published in the South African Journal of Science, describes the newly discovered phosphatized fossils that the paleontologists interpret as ancient sponge-like organisms and call them Otavia antique. They were found in Namibia in rocks ranging in age between 760 and 550 million years.
This discovery places the origin of animals up to 150 million years earlier than it has previously been thought. It also supports the predictions based on genetic sequencing that the first animals were sponges.
Scanning electron microscopy image of Otavia antique (Dr. Bob Brain et al)
“We term the putative fossils Otavia, because they have been recovered most abundantly from black limestone units of the Otavi Group of Namibia,” wrote Dr. Bob Brain of the Northern Flagship Institution in Pretoria, South Africa, and Dr. Anthony Prave of the University of St Andrews, UK, and their co-authors.
“Otavia have also been found in the Nama Group of Namibia. Both Otavi and Nama Groups are several kilometres thick and comprised of siliciclastic and carbonate rocks deposited in shallow marine shelf and slope environments.”
The paleontologists said that the general shape of O. antique is elongate ovoid to globular measuring from as small as 0.3 mm to as large as 5 mm in the longest dimension.
The outer surface of fossilized organisms is perforated and pierced by numerous small holes, typically 5 mm – 20 mm across, as well as a number of larger openings that form raised turrets or mounds several to many tens of microns in diameter.
“The fossils demonstrate a complex rigid structure consistent with requirements for the feeding mechanism of sponges, suggesting the presence of animals of a high level of organization. The rocks of southern Africa have yet again yielded up key evidence regarding the history of life,” Dr. Robert Gess of University of the Witwatersrand, South Africa, wrote about this discovery in the separate paper published in the same issue of the South African Journal of Science.
