Sponges Around Before End Of "snowball Earth"

[Guest solius symbiosus]

Evidence of sponges are present in rocks that pre-date the end of the Marinoan glaciation. Many assumed the that multi-cellular life evolved after the end of the "Snowball Earth" period. Too, it is unlikely that Porifera would have thrived if the planet was covered in ice.

Ancient sponges leave their mark

By Jonathan Amos

Science reporter, BBC News

The rocks date to a time of dramatic glaciation on Earth

Traces of animal life have been found in rocks dating back 635 million years.

The evidence takes the form of chemical markers that are highly distinctive of sponges when they die and their bodies break down in rock-forming sediments.

The discovery in Oman pushes back the earliest accepted date for animal life on Earth by tens of millions of years.

Scientists tell Nature magazine that the creatures' existence will help them understand better what the planet looked like all that time ago.

"The fact that we can detect these signals shows that sponges were ecologically important on the seafloor at that time," said lead author Gordon Love, from the University of California, Riverside.

"We're not saying we captured the first animal; we're saying they're an early animal phylum and we're capturing them when their biomass was significant."

...

The discovery is fascinating because it pre-dates the end of the Marinoan glaciation, a deep freeze in Earth history that some argue shrouded the entire planet in ice.

Scientists often refer to the term "snowball Earth" to describe conditions at this time.

So to find animal life apparently thriving during this glaciation seems remarkable, commented Jochen Brochs, from the Australian National University, Canberra.

"If there really was a snowball Earth, how did those sponges survive? The full snowball Earth hypothesis would predict that the oceans were frozen over by 2km, even at the equator," he told BBC News.

...

Dr Love's view is that the presence of these animals puts limits on the scale of the ice coverage.

"I believe there were areas of what we might call refugia - areas of open ocean where biology could go on. And in this case, it could be evidence that we had some sort of evolutionary stimulation of new grades of organisms as well."

http://news.bbc.co.uk/2/hi/science/nature/7871099.stm

-------------------------------

Abstract:

Fossil steroids record the appearance of Demospongiae during the Cryogenian period

Gordon D. Love, et al.

The Neoproterozoic era (1,000–542 Myr ago) was an era of climatic extremes and biological evolutionary developments culminating in the emergence of animals (Metazoa) and new ecosystems1. Here we show that abundant sedimentary 24-isopropylcholestanes, the hydrocarbon remains of C30 sterols produced by marine demosponges, record the presence of Metazoa in the geological record before the end of the Marinoan glaciation (635 Myr ago). These sterane biomarkers are abundant in all formations of the Huqf Supergroup, South Oman Salt Basin, and, based on a new high-precision geochronology2, constitute a continuous 100-Myr-long chemical fossil record of demosponges through the terminal Neoproterozoic and into the Early Cambrian epoch. The demosponge steranes occur in strata that underlie the Marinoan cap carbonate (>635 Myr ago). They currently represent the oldest evidence for animals in the fossil record, and are evidence for animals pre-dating the termination of the Marinoan glaciation. This suggests that shallow shelf waters in some late Cryogenian ocean basins (>635 Myr ago) contained dissolved oxygen in concentrations sufficient to support basal metazoan life at least 100 Myr before the rapid diversification of bilaterians during the Cambrian explosion. Biomarker analysis has yet to reveal any convincing evidence for ancient sponges pre-dating the first globally extensive Neoproterozoic glacial episode (the Sturtian, 713 Myr ago in Oman2).

http://www.nature.com/nature/journal/v457/...ature07673.html

[Auspex]

One phrase in the abstract boggled my mind: "chemical fossil record".

[Guest solius symbiosus]

^^If you think about it, kerogen is essentially a "chemical fossil record".

[PaleoPutz]

I believe this research was funded by fuel companies looking for oil or something. I think the sponge stuff happened by coincidence.. that maybe why it reads a bit funny.

[grampa dino]

Where any of the sponges called Square Pants

[Guest solius symbiosus]

I believe this research was funded by fuel companies looking for oil or something.

Probably not looking for oil as life was too scarce in the Pre-Cambrian to produce viable fields.

[PaleoPutz]

Probably not looking for oil as life was too scarce in the Pre-Cambrian to produce viable fields.

I just guessed because the company that paid for it is called Petroleum Development Oman which is a hydrocarbon production and research company.

[Guest Nicholas]

ScienceDaily (Feb. 5, 2009) — An international research team of scientists from UC Riverside, the Massachusetts Institute of Technology and other institutions has found the oldest evidence for animals in the fossil record.

Find the article HERE!