it is quite clear that 'species' as used by palaeontologists and 'species' as used by other biologists cannot be the same. a palaeontologist can only use visible features of a fossil, which are only a small part of the traits of a living species. not only that, but many species which are virtually identical can only be distinguished by their dna. this relatively recent discovery of sibling species is very important, and their numbers are growing rapidly. we underestimated the effect of convergent evolution.