Origin of vertebrates

Article By:

Elliott, David K. School of Earth Sciences and Environmental Sustainability, Northern Arizona University, Flagstaff, Arizona.

Last reviewed:2014

DOI:https://doi.org/10.1036/1097-8542.YB150955

The fossil record for vertebrates is arguably one of the best of any major group of organisms and enables the evolutionary development from primitive jawless fish through more advanced fish to tetrapods (and ultimately humans) to be delineated. Despite this, it is often not clear when major groups diverged from each other, particularly when the first vertebrates separated from other chordates. Because the earliest vertebrates do not appear to have possessed mineralized skeletons, their preservation potential is low and their fossil record is very sparse. However, in recent years, material from the Cambrian Konservat-Lagerstätten (cases of exceptional soft-tissue preservation), particularly that of Chengjiang, South China, has pushed the fossil record of vertebrates down into the Early Cambrian Period [525 million years ago (MYA)], indicating that vertebrate origins must lie even earlier. This fits with divergence times based on molecular data, which suggest that chordates had evolved in the Upper Precambrian (Ediacaran Period, 600–545 MYA) and that vertebrates may have diverged not long afterward.

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