Cambrian Explosion: role of oxygen (Introduction)

by dhw, Wednesday, January 06, 2016, 15:22 (1543 days ago) @ David Turell

DAVID: It has been proposed that an increase in oxygen triggered the Cambrian explosion. New date has appeared showing that oxygen was plentiful (4%) for some animals about 800 million years earlier:

QUOTE: “The water column had an oxygen concentration at least 4 % of present atmospheric levels (PAL). That should be sufficient for animals to exist and evolve," says Canfield.”

QUOTE: "'Researchers know of simple animals, such as sponges and worms, that today are capable of managing with less than 4% PAL, even much less."

QUOTE: "'Sponges probably resemble some of the first animals on Earth. If they manage with less than 4 % today's oxygen levels, it is likely that the first animals could do with these concentrations or less," says Canfield.

QUOTE: Maybe the oxygen rise had less to do with the animal revolution than we previously assumed," says Hammarlund."

David's comment: This leaves the Cambrian period with no explanation from an evolutionary standpoint as to why it appeared when it did. It remains the main stumbling block to Darwin's chance theory.

If the Cambrian produced NEW phyla, how can anyone possibly know that those hitherto non-existent organisms could have existed on 4% of the oxygen we have today? Look at the bold: should be, probably, it is likely, maybe...This is pure speculation, and I am surprised you take it seriously. The Cambrian remains an unsolved mystery, the oxygen factor remains a possible explanation, though we still need a mechanism to take advantage of whatever changes took place.

Complete thread:

 RSS Feed of thread

powered by my little forum