A new book explores the evolution and diversity of life’s scaffolding
Jan Zalasiewicz and Mark Williams
Oxford Univ., $24.95
For much of life’s reign on Earth, organisms got by without skeletons. But since that innovation evolved about 550 million years ago, there’s been an evolutionary arms race of epic proportions.
One of the first competitors was Cloudina, a small seafloor creature whose exterior skeleton almost certainly evolved in response to predation: In well-preserved groups of fossils, up to a fifth of these critters’ exoskeletons show holes or other evidence of being attacked.
In the eras since, in response to predation and a wide range of other challenges, life has evolved a wild diversity of such structures, as described in the aptly named Skeletons. The