Back from the dead: One third of 'extinct' animals turn up again
By David Derbyshire Environment Editor
Last updated at 9:10 AM on 29th September 2010
An okapi: Tracks were seen by researchers five years ago for the first time since 1959
Conservationists are overestimating the number of species that have been driven to extinction, scientists have said.
A study has found that a third of all mammal species declared extinct in the past few centuries have turned up alive and well.