Did Sea Life Arise Twice?

eldavojohn writes "Dr. Adam Maloof has found fossils of sea sponges in Australia from 650 million years ago. You might think this is no big deal unless you consider that sea sponges were thought to have arisen 520 million years ago. These fossils predate the oldest hard bodied fossils we have by a hundred million years. Dr. Maloof is now wondering if life might have arisen twice after the first attempt was quashed 635 million years ago: 'Since animals probably did not evolve twice, we are suddenly confronted with the question of how some relative of these reef-dwelling animals survived the Snowball Earth.' So how is it that life survived the Marinoan glaciation? The BBC has a video on the topic and Wikipedia has a time line of the Proterozoic Eon into the Paleozoic Era."

Comments

Re:Life fills a space defined by its environment

[mcgrew]

OK, since I took the two seconds necessary to RTFA, the summary's title is wrong. TFA specifically says NOT that life evolved twice, but that the date the Earth was inhabited was pushed back.

If correct, the finding would mean that animal life existed before the Marinoan glaciation - a global catastrophe known as 'Snowball Earth' when the entire planet was covered in ice.

Previously it was believed that animal life first emerged after the Snowball Earth event around 635million years ago.
Dr Maloof told The Times: 'No one was expecting that we would find animals that lived before the [Snowball Earth] ice age.
'Since animals probably did not evolve twice, we are suddenly confronted with the question of how some relative of these reef-dwelling animals survived the Snowball Earth.'

Now I have to read your links, at least the first one. But as to the second,
Does this mean that life on other planets arises identically or near-identically to our own, or that the origin of life on earth comes from elsewhere?

There is no proof at all that life exists anywhere else except on earth. When and if we find life elsewhere, than we can make conjecture about panspermia, until then it's just science fiction. Not even junk science.