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. Author manuscript; available in PMC: 2020 Mar 1.
Published in final edited form as: Immunogenetics. 2019 Jan 24;71(3):251–261. doi: 10.1007/s00251-019-01105-0

Fig. 2.

Fig. 2

Evolution of adaptive immunity

Phylogeny of animals is shown on the left along with the divergence times based on molecular data compiled by Blair and Hedges (Blair and Hedges 2005). The phylogenetic distribution of key elements discussed in this review is shown on the right. It is conspicuous that birds lack proteasome elements specialized for antigen presentation by MHC class I molecules. This figure was modified from the previously published one (Murata et al. 2018). Mya, million years ago