Chitons and Gastropods (Haliotidae Through Adeorbidae) from the Western Pacific Islands
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Chitons and Gastropods (Haliotidae Through Adeorbidae) From the Western Pacific Islands GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 Chitons and Gastropods (Haliotidae Through Adeorbidae) From the Western Pacific Islands By HARRY S. LADD GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 Description and preliminary paleoecologic in terpretations of fossil moll usks from seven island groups UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1966 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director Library ut' Oongivw, catalog-curd Xo. GS 66-257 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price $1.25 (paper cover) CONTENTS Page Page Abstract ________________ __ - 1 Paleontology Continued Introduction - 1 Paleoecology ____ 11 Area and localities 1 Faunal relations _ 15 Purpose and scope ____ .. - 1 Systematic paleontology . 20 Earlier references to fossil mollusks _______ ______ 3 Chitons ________ - 21 Palau ____________________________- 3 Schizochitonidae _ _ 21 Mariana Islands ___________________ 3 Chitonidae _______________ ______ 23 Marshall Islands __________ _ _ 3 Acanthochitonidae _ ___ 24 Ellice Islands _____________________ 3 Gastropods ______ 25 Funafuti ________________________. 3 Haliotidae _ 25 Scissurellidae .. 26 New Hebrides _____________________ 3 Fissurellidae ________ 27 Fiji ______________________________ 4 Patellidae __________________-_ 32 Tonga ____________________________ 5 Trochidae ____________-__ - 33 Collections __________________________ 5 Stomatellidae ________ . 41 Acknowledgments _______-_______________ 6 Angariidae (Delphinulidae) 42 Geology ________________________________ 6 Turbinidae _______ - 43 Stratigraphy _________. 6 Phasianellidae ________ _ _ 53 Eocene ____________. Neritopsidae ______________ _ 55 Oligocene ____________ Neritidae _______________________- 55 Miocene ___________. Littorinidae _ 59 Iravadiidae ________________ ___ 59 Post-Miocene ________. Rissoidae ______________________ 60 Pliocene ________. .___________. 9 Assimineidae ____________________. 75 Pleistocene and Recent .___________. 9 Adeorbidae (Vitrinellidae) ____________ 75 Correlation ____________. .___________. 9 Localities __________ _______ __ ___ 81 Paleontology ____________________________ 9 References ______________________________ 89 Geographic and geologic distribution of species _____ 9 Index __________________________________ 93 ILLUSTRATIONS [Plates follow index") PLATE 1. Chitons. Page 2-16. Gastropods: FIGURE 3. Sketch map of Guam, Mariana Islands, showing 2. Haliotidae, Scissurellidae, and Fissurellidae. localities mentioned in text _______________ 82 3. Fissurellidae, Patellidae, and Trochidae. 4. Sketch map showing fossil localities on 4. Trochidae. Haipan, Mariana Islands __. 83 5. Trochidae, Stomatellidae, and Angariidae. 5-8. Maps showing locations of drill holes: 6-9. Turbinidae. 5. Eniwetok Atoll ______________ _ 84 10. Phasianellidae, Neritopsidae, Neritidae, and 6. Eniwetok Atoll ___________________ 85 Assimineidae. 7. Bikini Atoll ______ . 86 11. Neritidae, Littorinidae, Iravadiidae, and Rissoidae. 8. Funafuti Atoll _________ 86 12,13. Rissoidae 9-14. Maps showing fossil localities: 14. Rissoidae and Adeorbidae. 9. New Hebrides _____________________ 87 15, 16. Adeorbidae. 10. Viti Levu, Fiji _____ . 87 11. Fulanga, Lau, Fiji ____ . Page FIGURE 1. Index map showing location of island groups _ 2 12. Ongea, Lau, Fiji ____ . 2. Sketch map showing fossil localities in the 13. Lakemba, Lau, Fiji __ . 89 Goikul area, Palau _______________________ 81 14. Tongatabu, Tonga ____________________ 89 TABLES Page TABLE 1. Distribution of Cenozoic sediments in the island area _________________________ 7 2. Major stratigraphic subdivisions recognized in holes drilled in the Marshall Islands_________ 7 3. Correlation of Cenozoic units in the island area ______________________________ 10 4. Geographic distribution of species _________________________________________________________ 12 5. Geologic distribution of species _______________________________________. 16 6. Living Lido-Pacific mollusks that also occur in the upper Tertiary sediments of the island area 20 CHITONS AND GASTROPODS (HALIOTIDAE THROUGH ADEORBIDAE) FROM THE WESTERN PACIFIC ISLANDS By HARRY S. LADD ABSTRACT during the Miocene. Ties between the island area and the Cenozoic mollusks from seven island groups in the western Americas are suggested, but they are less impressive than rela Pacific are treated systematically. The islands form a broad belt tionships with the Indo-Pacific. spreading 4,000 miles across tropical latitudes from the Mariana Islands and Palau on the northwest through the Marshall, Ellice INTRODUCTION and New Hebrides groups to Fiji and Tonga on the southeast. Each of the island groups has a section of Quaternary limestones AREA AND LOCALITIES and all except the Ellice group are known to have a Tertiary The islands of the western Pacific considered here sequence as well. The known Tertiary in all island groups, except form a broad and somewhat irregular belt spreading that in the New Hebrides, extends back as far as the Eocene. No Paleocene rocks have been recognized. 4,000 miles across the tropical latitudes of the western Two hundred and eight species and subspecies are described. Pacific, from the Mariana Islands and Palau on the These include representatives of 3 families of chitons and 16 northwest to Fiji and Tonga on the southeast (fig. 1). families of gastropods (Haliotidae through Adeorbidae). Three The belt measures approximately 1,000 miles in width new subgenera of gastropods are described: Vitiastraea (sub- and includes seven island groups Marshall,- Ellice, genus of Astraea), Subditotectarius (subgenus of Tectarius), and Mariana, Palau, New Hebrides, Fiji, and Tonga. Of Ailinzebina (subgenus of Zebina). Sixty-seven new species and five new subspecies are described. The species discussed in the these, only the Marshall and Ellice Islands lie in the present report comprise approximately one-sixth of available Pacific Basin proper, within the circum-Pacific 'andesite collections. line. As thus outlined, the belt includes all of Micronesia About three-fourths of the new forms were recovered from the and eastermost Melanesia and separates Indonesia from drill holes in the Marshall Islands; the remainder, from outcrop most of the Pacific Basin proper. samples, are divided almost equally between Palau and Fiji. A few of the new forms from the Marshall Islands also occur in Palau and Fiji. PURPOSE AND SCOPE The richest and most widespread assemblages are Miocene This primarily paleontologic report deals mainly with (Tertiary / and g). Most of the mollusks are reef associated. large collections of fossil mollusks obtained by the U.S. Many, notably those of the limestones in the deep drill holes of the Marshall?, occur in beds that were deposited in lagoons; Geological Survey and other governmental agencies dur some species occur in beds that were accumulated on tidal flats; ing field investigations in Micronesia in the years im a few species lived in fresh or brackish waters. mediately following World War II. These investigations The assemblages of fossil mollusks, like those living in the were of two types: (1) Deep drilling at Bikini Atoll in area today, are Indo-Pacific in general aspect. The strongest dis connection with Operation Crossroads in 1947 and at cernible ties are with living and fossil faunas of tropical Indo Eniwetok Atoll for the Atomic Energy Commission in nesia, rather than with faunas from more southerly areas (south ern Australia and New Zealand) or more northerly areas (the 1951-52; all deep drilling was under the supervision of Ryukyu Islands and Japan). Thirty-throe of the des-ribed species U.S. Geological Survey personnel. (2) Detailed mapping that still live in the island area have been there at least since projects carried on by the U.S. Geological Survey under late Tertiary time. Of this group, the shells of 25 were recovered the sponsorship of the U.S. Army, Corps of Engineers, from Marshall Island drill holes, those of 10 from outcrops in in Palau, 1947-48, Saipan, 1948-49, Tinian, 1949-51, and Fiji. A few species that lived in the island area during the Guam, 1951-54. The Survey's collections from Guam Tertiary are now living only in other parts of the Indo-Pacific region. supplement even larger collections made earlier by the Numerous living Indo-Pacific species had close relatives, some Pacific Island Engineers under contract with the U.S. perhaps ancestral, in the island area during the upper Tertiary. Navy. In the Miocene of Bikini is a species of Pisulina, a genus known In an attempt to make the study of island fossil mol previously only from a few species living near India and Ceylon. lusks as complete as possible, collections from other The neanvt relatives of a lower Miocene CtjniNcn of Eniwetok live off the Capo of Ciood Hope, South Africa, tichtzachitott, the island groups Fiji, Tonga, New Hebrides, and Ellice reef chiton that lives today in the Philippines and northern Aus Islands have been reviewed. Some material from these tralia, had representatives in the Marshall Islands and Palau islands, already described in print, has been reexamined. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS FIGTRK 1. Location of island groups from which fossil mollusks have been obtained. Dashed line marks structural boundary of Pacific Basin (andesite line). The mollusks