title: Mineralized rods and cones suggest colour vision in a 300 Myr-old fossil fish.
abstract: Vision, which consists of an optical system, receptors and image-processing capacity, has existed for at least 520 Myr. Except for the optical system, as in the calcified lenses of trilobite and ostracod arthropods, other parts of the visual system are not usually preserved in the fossil record, because the soft tissue of the eye and the brain decay rapidly after death, such as within 64 days and 11 days, respectively. The Upper Carboniferous Hamilton Formation (300 Myr) in Kansas, USA, yields exceptionally well-preserved animal fossils in an estuarine depositional setting. Here we show that the original colour, shape and putative presence of eumelanin have been preserved in the acanthodii fish Acanthodes bridgei. We also report on the tissues of its eye, which provides the first record of mineralized rods and cones in a fossil and indicates that this 300 Myr-old fish likely possessed colour vision.
authors.affiliation: Center for Marine Environment Studies, Kumamoto University, 6061 Matsushima-cho, Kami-amakusa, Kumamoto 861-6102, Japan.
authors.forename: Gengo
authors.initials: G
authors.lastname: Tanaka
authors.affiliation: Department of Life Sciences, Natural History Museum, London SW7 5BD, UK.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Parker
authors.affiliation: Gunma Museum of Natural History, Tomioka City, Gunma 370-2345, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Hasegawa
authors.affiliation: Department of Geology, University of Leicester, Leicester LE1 7RH, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Siveter
authors.affiliation: Gunma Industrial Technology Center, 884-1 Kamesato, Maebashi, Gunma 379-2147, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Yamamoto
authors.affiliation: Gunma Industrial Technology Center, 884-1 Kamesato, Maebashi, Gunma 379-2147, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Miyashita
authors.affiliation: Gunma Industrial Technology Center, 884-1 Kamesato, Maebashi, Gunma 379-2147, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Department of Chemistry, Fujita Health University School of Health Sciences, Toyoake, Aichi 470-1192, Japan.
authors.forename: Shosuke
authors.initials: S
authors.lastname: Ito
authors.affiliation: Department of Chemistry, Fujita Health University School of Health Sciences, Toyoake, Aichi 470-1192, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Wakamatsu
authors.affiliation: 1] Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-1-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8521, Japan [2] Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Mukuda
authors.affiliation: Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-1-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8521, Japan.
authors.forename: Marie
authors.initials: M
authors.lastname: Matsuura
authors.affiliation: Graduate School of Education, Hiroshima University, 1-7-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8524, Japan.
authors.forename: Ko
authors.initials: K
authors.lastname: Tomikawa
authors.affiliation: Central Research Laboratory, Okayama University Medical School, 2-5-1 Shikada, Kita-ku, Okayama 700-8558, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Furutani
authors.affiliation: Research Center for Human and Environmental Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Kyushu University Museum, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Haruyoshi
authors.initials: H
authors.lastname: Maeda
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002119:Calcium Carbonate / Q000737:chemistry*; D003116:Color; D055253:Color Vision / Q000502:physiology*; D005399:Fishes / Q000033:anatomy & histology / Q000145:classification / Q000502:physiology*; D005580:Fossils; D008855:Microscopy, Electron, Scanning; D010802:Phylogeny; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology / Q000648:ultrastructure*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology / Q000648:ultrastructure*
chemical_list: D002119:Calcium Carbonate