Life of the Oceans - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 158

animal (the English tabloid newspaper the Sun reported it—and we
merely pass this on without further comment—as 'The World's Old-
est Todger'). Even their parenting skills are preserved, for ostracods
brood their young within the carapace, carefully nurturing the next
generation: in the Herefordshire nodules both eggs and young are
preserved inside the carapace. The ocean world had become, in many
respects, surprisingly modern (see Plate 3).
Marine life survived the five mass extinction events of the Phanero-
zoic, each characterized by a more than 50 per cent loss of marine
species. It survived the greatest environmental calamity of all, at the
Permian-Triassic boundary 250 million years ago, when more than
95 per cent of marine species went extinct. And yet this extinction,
and those that followed, could not extinguish the life of the seas, or its
complexity. No phylum has ever gone extinct since the Cambrian,
and a few million years after each mass extinction event the complex-
ity of the ocean food web essentially reconfigured itself. It witnessed
the rise of new innovations, such as the development of predators
with shell-crushing mouths, and of new organisms colonizing the
plankton, such as foraminifera; it witnessed the colonization of the
deep ocean.
The journey through the Phanerozoic seas witnessed, too, the colo-
nization of land by plants and animals. The greening of the land took
place quickly—as with the Cambrian radiation of life, a mere few tens
of millions of years made a lot of difference. When the animals pre-
served in Chengjiang were hunting and being hunted in the Cam-
brian, the land was still barren. Only when the sophisticated and
modern-looking Herefordshire animals inhabited the Silurian sea
floor was life creeping on to land, in the form of pioneering green
stalks, and a few hardy millipedes. By the middle of the succeeding
Devonian Period, true forests had evolved, covered by all manner of
scuttling, jumping, and biting things. From then on, the biosphere