 |
| A scanning electronic microscope image of the 600 million-year-old sponge-like animal fossil [Credit: Zongjun Yin] |
Sponges, also known as Porifera, are multicellular organisms that have bodies covered with pores and channels that allow water to circulate through them.
Scientists have still to confirm when they first appeared on Earth.
Estimates range from 700 million years ago to a time known as the Cambrian period, which took place 541 million to 485 million years ago.
The latest finding would place the sponge around 60 million years before the Cambrian started.
Researchers want to pin down the date because they believe it is key to understanding early animal evolution.
The split between sponges and most other animals was a major event in the early history of life on our planet.
The sponge, found in the Doushantuo Formation, is just over one millimetre in height and width, according to researchers from the Nanjing Institute of Geology and Palaeontology.
To get a good look, scientists used scanning electron microscopy and X-ray technology.
The team has named it Eocyathispongia qiania and say that it is made up of hundreds of thousands of cells.
Its structure is formed in three tube-like chambers that are fixed to a common base, with cell structures that resemble those in modern sponges.
Scientists also found surface cells that indicate pores, like modern sponges, which control water flowing into the organism.
There was an area inside one of the tubes with pits surrounded by raised collars - a possible precursor to choanocyte cells which modern sponges use to move water through their bodies.
As well as being one of the oldest of the really old sponge fossils found, the find also represents one of the most pristine.
The researchers say they have more material from the site where the sponge was found, and will be sifting through it looking for more tiny sponges and perhaps other organisms.
Lead author of the paper published in Proceedings of the National Academy of Sciences, Maoyan Zhu said that the find suggests that animals on Earth began diversifying 600 million years ago.
'Discovery of additional specimens would confirm that the fossil represents a Precambrian sponge,' he said.
'But features of the fossil are consistent with sponge anatomy… fossils of similarly advanced eumetazoans [all major animal groups except sponges] may yet lie in the fossil record.'
Author: Ellie Zolfagharifard | Source: Dailymail [March 11, 2015]