Mr. Croll estimates that about sixty million years have elapsed since the Cambrian period, but this, judging from the small amount of organic change since the commencement of the Glacial epoch, appears a very short time for the many and great mutations of life, which have certainly occurred since the Cambrian formation;
eta aurreko 140 milioi urteak nekez jo daitezke nahikotzat kanbriar aldian jada baziren bizi-forma bariatuen garapenarako.