Ancient Fossils Have Evolution’s First Shells

[n2doc]

By Brandon Keim June 13, 2011 | 4:28 pm | Categories: Biology, Earth Science, Evolution


A series of spectacularly preserved, 750-million-year-old fossils represent the microscopic origins of biomineralization, or the ability to convert minerals into hard, physical structures. This process is what makes bones, shells, teeth and hair possible, literally shaping the animal kingdom and even Earth itself.

The fossils were pried from ancient rock formations in Canada’s Yukon by earth scientists Francis Macdonald and Phoebe Cohen of Harvard University. In a June Geology paper, they describe their findings as providing “a unique window into the diversity of early eukaryotes.”

That window opens into an evolutionary period less celebrated than the kaleidoscopic radiations of the Cambrian, but in its own way no less impressive. The simple single-celled organisms that dominated life’s first few billion years were rapidly becoming more complex, building a store of innovations that sustained some through the so-called Snowball Earth period, when Earth’s climate turned so cold that the equator resembled Antarctica.


One such innovation was biomineralization, though evidence for its occurrence at this time was inconclusive. Using molecular clocks and genetic trees to reverse-engineer evolutionary histories, previous research placed the beginning of biomineralization at about 750 million years ago. Around that time, the fossil record gets suggestive, turning up vase-shaped amoebas with something like scales in their cell walls, algae with cell walls possibly made from calcium carbonate and sponge-like creatures with seemingly mineralized bodies. But in each of these examples, caveats abound. What appears to be biomineralization might be a fossil illusion produced as soft tissue turned to stone.

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http://www.wired.com/wiredscience/2011/06/first-shells/

[Nihil]

1. Interesting article - thanks for posting! (n/t)

:toast:

[AlecBGreen]

2. thanks!

:thumbsup: