Volume 28, Issue 7, Pages 1101-1107.e2 (April 2018) The Only Known Jawed Vertebrate with Four Eyes and the Bauplan of the Pineal Complex  Krister T. Smith, Bhart-Anjan S. Bhullar, Gunther Köhler, Jörg Habersetzer  Current Biology  Volume 28, Issue 7, Pages 1101-1107.e2 (April 2018) DOI: 10.1016/j.cub.2018.02.021 Copyright © 2018 Elsevier Ltd Terms and Conditions

Current Biology 2018 28, 1101-1107.e2DOI: (10.1016/j.cub.2018.02.021) Copyright © 2018 Elsevier Ltd Terms and Conditions

Figure 1 Pineal Complex in Extant Vertebrates The relative development of parapineal (pp) and pineal (pi) organs in major vertebrate clades, according to the homologies promulgated here. In coelacanths, the organs are distinct but communicate and share a common connection with the rest of the brain; in turtles, the organs are only distinct in early ontogeny [4]. In stem (and occasionally crown) representatives of many basal gnathostome clades, there is a median foramen that is usually inferred to have housed the pineal organ. A median foramen is lost numerous times in vertebrate evolution. Although only lepidosaurs, among extant vertebrates, have a foramen for the parapineal organ (parietal eye), it is unknown at which point this transition occurred in amniotes. See key at lower right. Relationships of turtles are after [3]; silhouettes are from http://phylopic.org. Current Biology 2018 28, 1101-1107.e2DOI: (10.1016/j.cub.2018.02.021) Copyright © 2018 Elsevier Ltd Terms and Conditions

Figure 2 The Parietal in Saniwa ensidens (A) Outline of skull (after [11]) showing position of two specimens. (B and C) YPM VP 1074, in dorsal and ventral views, showing both parietal and pineal foramina. (D) Detail of ventral opening of pineal foramen, showing posterolateral sulcus. (E and F) YPM VP 613, in dorsal and ventral views, showing both foramina. Note the two puncture wounds on the left side. (G) Computed tomography (CT) reconstruction of YPM VP 613 showing the segmented surface of both foramina, with a corner removed. (H) CT reconstruction of YPM VP 1074 showing the segmented surface of both foramina, with the right-middle portion of the bone partly transparent. Scale bar, 5 mm. Abbreviations: f.pa., parietal foramen; f.pi., pineal foramen; s, sulcus. See also Figures S2 and S3. Current Biology 2018 28, 1101-1107.e2DOI: (10.1016/j.cub.2018.02.021) Copyright © 2018 Elsevier Ltd Terms and Conditions

Figure 3 Histology of Epithalamus in the Monitor Lizard Varanus exanthematicus Left-of-midline sagittal slice, stained using Crossmon’s trichrome, showing the left wall of the parietal eye above a plug of connective tissue filling the parietal foramen. Scale bar, 1 mm. Abbreviations: ha., habenula; pa., parietal bone; pa.eye, parietal eye; par., paraphysis; p.c., posterior commissure; pi., pineal organ; pi.a., anterior pineal artery; s.l., longitudinal sinus; t.v., terminal vesicle of pineal. Current Biology 2018 28, 1101-1107.e2DOI: (10.1016/j.cub.2018.02.021) Copyright © 2018 Elsevier Ltd Terms and Conditions

Figure 4 Phylogenetic Bracketing of Pineal Anatomy in the Common Ancestor of Varanus and Saniwa (A) Pineal tract present (black) or absent (white). (B) A terminal vesicle of the pineal, with or without an eye-like structure, present (black) or absent (white). The tree is based on the molecular topology of squamate relationships [12], but the results are the same for the morphological topology [10]. See also Data S1. Current Biology 2018 28, 1101-1107.e2DOI: (10.1016/j.cub.2018.02.021) Copyright © 2018 Elsevier Ltd Terms and Conditions