Our Earliest Animal Ancestors
Sponges were probably the last common ancestor of
all animal life.
The Cambrian “explosion” that occurred
543 million years ago is one of the biggest mysteries of biology. It is at this
point in the fossil record that a multitude of animal forms suddenly appears,
for reasons that are not well understood. The first animals preceded the
explosion, but they were presumably small, fragile and ephemeral, containing
little or nothing able to
fossilize.
The earliest putative animal fossils date to the Ediacarian period, about 630 to 542 million years ago. These primitive organisms “must have had a significant complement of genes inherited from their ancestors, that allowed multicellularity, differentiation and signaling” to emerge, Summons says.
Genetic analysis shows that the first sponges date to 650 to 700 million years ago, says Kevin Peterson, an associate professor of biological sciences at Dartmouth College, who adds that sponges were probably the last common ancestor of all animal life.
Solid article with interesting questions about the origins of the gut, nervous system, aerobic metabolism. Should be a fun project for years.
The earliest putative animal fossils date to the Ediacarian period, about 630 to 542 million years ago. These primitive organisms “must have had a significant complement of genes inherited from their ancestors, that allowed multicellularity, differentiation and signaling” to emerge, Summons says.
Genetic analysis shows that the first sponges date to 650 to 700 million years ago, says Kevin Peterson, an associate professor of biological sciences at Dartmouth College, who adds that sponges were probably the last common ancestor of all animal life.
Solid article with interesting questions about the origins of the gut, nervous system, aerobic metabolism. Should be a fun project for years.
Posted: Thu - August 9, 2007 at 07:12 AM