11. The ginkgo tree is what scientists call a living fossil . 12. "It really is a living fossil , " said Barbara Briggs, the institution's scientific director. 13. Moreover, the echidna, often described as a living fossil , has hind feet that face backward. 14. Some living fossils are taxa that were known from fossils before living representatives were discovered. 15. In several cases, living fossils are species-poor lineages, but this is not always the case. 16. Because the helodermatids have remained relatively unchanged morphologically, they are occasionally regarded as living fossils . 17. The plant has existed for over 300 million years and is considered a living fossil . 18. The most astonishing sequence showed Vampiroteuthis, the living fossil . 19. It's one of these classic living fossil animals. 20. In the intervening 325 million years, phreatoicideans have changed little, and are thus considered living fossils .
