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. Author manuscript; available in PMC: 2008 Aug 12.
Published in final edited form as: Nat Rev Neurosci. 2005 Feb;6(2):151–159. doi: 10.1038/nrn1606

Figure 2. Simplified modern view of vertebrate evolution.

Figure 2

The diagram begins with the fish group that contains the most recent ancestors of land vertebrates. This differs from the classic view in that instead of giving rise to reptiles, ancestral amphibians are thought to have given rise to stem amniotes. Stem amniotes then split into at least two groups: the sauropsids, which gave rise to all modern reptiles as we know them today; and the therapsids, which, through a series of now-extinct intermediate forms, evolved into mammals. Many sauropsids (reptiles) are currently living. Solid horizontal lines indicate temporal fossil evidence. Dashed lines indicate proposed ancestral links based on other types of data. MYA, million years ago Based on REFS 85,86.