‘We do not have any available fossil group which can categorically be claimed to be the ancestor of any other group. We do not have in the fossil record any specific point of divergence of one life form for another and generally each of the major life groups has retained its fundamental structural and physiological characteristics throughout its life history and has been conservative in habitate.’
Prof. Carter (Fellow of Corpus Christi College, Cambridge) in ‘Structure and Habit in Vertebrate Evolution’, Sidgwick and Jackson, London, 1967.