Re: News: Signs point to sponges as earliest animal life

On Feb 5, 12:17=A0pm, "Robert Karl Stonjek" <rston...@xxxxxxxxxxxxxx>
wrote:
Signs point to sponges as earliest animal life
February 4th, 2009 in General Science / Biology

(PhysOrg.com) -- Even Charles Darwin was puzzled by the apparently sudden
appearance in the fossil record of a great variety of multicellular
creatures - a rapid blossoming known as the Cambrian explosion. Since the=
n,
the origin of animals was found to extend back earlier, through a period
known as the Ediacarian. Now, evidence found by researchers at MIT, UC
Riverside and other institutions shows that the first complex life forms =
may
in fact have appeared much earlier still.

Our earliest animal ancestors, it appears, were sponges - multicellular
animals that feed by passing seawater though a complex system of internal
channels. And these earliest sponges may predate the Ediacarian period by=
as
much as 80 million years, this new evidence shows.

Soft-bodied animals such as sponges are very rarely preserved as fossils,=
so
finding evidence of their early appearance required some clever detective
work. The key turned out to be an examination of unusual chemicals: stero=
ids
of a particular type produced abundantly by sponges but virtually never b=
y
simpler organisms.

Studying an unusually well preserved long sequence of strata found in Oma=
n,
the research team was able to extract these "chemical fossils" from a lar=
ge
number of samples spanning a range of tens of millions of years - before,
during and after the Ediacarian period. This provided clear evidence that
sponges must have evolved long before the great variety of multicellular
organisms that proliferated at the dawn of that period.

The new research, which appears this week in the journal Nature, was
conducted in MIT's Department of Earth, Atmospheric and Planetary Science=
s
(EAPS), under the direction of Professor of Geobiology Roger Summons. He
says that the study began when he was asked to examine samples of oil fro=
m
wells in Oman that tap into the oldest oil-producing fields in the world.
The oil samples from these wells "are unique in geological history for th=
eir
great age and geochemical composition, so we were looking for unusual
molecular fossils." At the same time, another MIT professor, Samuel Bowri=
ng,
and his postdoc, Daniel Condon, were able to assign precise ages to a num=
ber
of volcanic ash layers in the same wells using uranium-lead geochronology
techniques developed in his laboratory. The combination of the precise ag=
es
and diagnostic chemical fossils is a particularly compelling aspect of th=
e
research.

And, after painstaking chemical analysis, they found sponge-derived stero=
ids
in abundance - and with them, strong new evidence that sponges, among the
simplest forms of multicellular life, were indeed the first such organism=
s
on Earth. In short, they had found clear signs of the very base of the
evolutionary tree of animal life.

"I'm not surprised by any of this," Summons says, because others had alre=
ady
hypothesized, based on genomic evidence, that sponges were the earliest f=
orm
of animal life. But that evidence had remained somewhat controversial, an=
d
with the new findings "we nailed it by removing all sorts of ambiguities.=
"

"This might also represent the advent of the earliest reef systems made b=
y
animals rather than microbes," Summons says. And the establishment of tha=
t
new ecological niche may have helped pave the way for the later explosion=
of
complex organisms, around 580 million years ago.

At that time in geological history, the Earth was just coming out of the
last of its "snowball Earth" phases, when the entire planet was shrouded =
in
ice. Since the new findings show that complex life seems to have begun te=
ns
of millions of years before that, that means these organisms were able to
survive through that extreme episode of glaciation, something that many
scientists had thought was impossible. This provides new evidence that th=
e
freezing was not absolute, but instead left some open patches of water.

"There's plenty of evidence in these rocks that there were places on Eart=
h
where life was flourishing" during this snowball episode, known as the
Cryogenian, Summons says. "There must have been some refugia. Life certai=
nly
didn't shut down."

The lead author of the Nature paper is Gordon D. Love, who was a postdoc =
at
MIT when the research was done and is now a professor at the University o=
f
California, Riverside. Other authors include Emmanuelle Grosjean another
former postdoc now at Geoscience Australia; Charlotte Stalvies of the
University of Newcastle upon Tyne, U.K.; postdoc David A. Fike and former
MIT professor John Grotzinger of Caltech; graduate students Alexander
Bradley, Amy Kelly, Maya Bhatia; Bowring and Condon; and William Meredith
and Colin Snape of the University of Nottingham, U.K.

The work was funded by Petroleum Development Oman, the NASA Exobiology
Program, the NSF EAR program, the Agouron Institute and the NASA
Astrobiology Institute.

Provided by MIThttp://www.physorg.com/news152976776.html

Posted by
Robert Karl Stonjek

I think sponges really kick started evolution by it's food in waste
out processes
that were s much more advanced than anything seen before. That quickly
evolved
to the rest.

.

Relevant Pages

  • News: Signs point to sponges as earliest animal life
    ... Now, evidence found by researchers at MIT, UC ... Riverside and other institutions shows that the first complex life forms may ... Our earliest animal ancestors, it appears, were sponges - multicellular ... animals that feed by passing seawater though a complex system of internal ...
    (sci.bio.evolution)
  • Re: Conversation with an Evolutionist (part 1)
    ... But what about all the extinct fossilized animals? ... Can you explain how life got here, ... Evolution is the explanation of what happened after life ... fossils using trace radioactivity and see which animal came first. ...
    (talk.origins)
  • Re: Tree of Life
    ... an article on the animal branch of the tree of life: ... sponges, as the sister group to other animals. ...
    (talk.origins)
  • Re: Evolution... The Unlikely Steps...
    ... "If humans evolved from sponges, then how come there are still ... that all the crazy animals that came out of that, ... Just because Mesozoic mammals ...
    (talk.origins)
  • Re: News: And the first animal on Earth was a...
    ... other animals and diverged onto its own evolutionary path before the sponge. ... The cnidarians have nerve and muscle tissue. ... The sponges don't ...
    (sci.bio.evolution)