The invasion of land by ocean-dwelling plants and animals was one of the
most revolutionary events in the evolution of life on Earth, yet the
animal invasion almost failed--twice--because of the twin mass
extinctions of the Late Devonian Epoch. Some 359 to 375 million years
ago, these catastrophic events dealt our ancestors a blow that almost
drove them back into the sea. If those extinctions had been just a bit
more severe, spiders and insects--instead of vertebrates--might have
become the ecologically dominant forms of animal life on land.
This book examines the profound evolutionary consequences of the Late
Devonian extinctions and the various theories proposed to explain their
occurrence. Only one group of four-limbed vertebrates exists on Earth,
while other tetrapod-like fishes are extinct. This gap is why the idea
of "fish with feet" seems so peculiar to us, yet such animals were once
a vital part of our world, and if the Devonian extinctions had not
happened, members of these species, like the famous Acanthostega and
Ichthyostega, might have continued to live in our rivers and lakes.
Synthesizing decades of research and including a wealth of new
discoveries, this accessible, comprehensive text explores the causes of
the Devonian extinctions, the reasons vertebrates were so severely
affected, and the potential evolution of the modern world if the
extinctions had never taken place.