23 2008 3 1-11 The Bulletin of the Hobetsu Museum, no. 23, (March, 2008), p. 1-11 A review of the mosasaur fossils from Hobetsu and around area. Kazuhiko SAKURAI Hobetsu Museum; 80-6, Hobetsu, Mukawa-cho, Yufutsu-gun, Hokkaido, 054-0211 Japan Abstract This is a brief review of the mosasaur fossils in Hobetu Museum. Those are from Hobetsu and around area. In the nine specimens in the museum, seven ones are found from Hobetsu. The first study of the mosasaur fossil form Hobetsu area is Obata et. al. (1972). After opening of the museum (1982), Suzuki (1985a, b), Chitoku (1994), Sakurai et.al.(1999) reported some of them. I hope this report will be a basis of the further study for the mosasaurs in Japan and the related area. Key words- mosasaur, Hobetsu 2008 2 28 2007 1972 1982 1985ab1994 1999 1999 HMG-1075HMG-1076HMG-1077 1972 Plotosaurus (?) sp. NSM-PV15003 1984 1972 NSM-PV15003 3a HMG-10 3c HMG-11 3b HMG-12 3d 1985a 1984 HMG-12 Mosasaurus sp. indet. 1984 HMG-10 Mosasaurinae gen. et sp. indet. HMG-11 Plioplatecarpinae? gen. et sp. indet. HMG-370 Mosasauridae gen. et sp. indet.hmg-12 2008 By The Hobetsu Museum 1
1985b HMG-12 Mosasaurus hobetsuensis Mosasaurinae Mosasaurus M.conodon M.conodon M.missouriensis 1990 1984 HMG-10HMG-11HMG-12 HMG-370 HMG-371 1991 HMG-371 HMG-1 100m Santonian Campanian Campanian HMG-1 1986 HMG-371 Campanian 1994 HMG-371 Mosasaurus Plotosaurus Tylosaurus T.prorigerT.nepaeolicusT.haumuriensis Tylosaurus sp. 1999 1994HMG-1065 Mosasaurus prismaticus Mosasaurinae Mosasaurus 2004 HMG-1076HMG-1077 HMG-1075 2005 1990 HMG-12HMG-1065 HMG-371HMG-11HMG-10HMG-370 2004 HMG-1075 HMG-1076HMG-1077 Caldwell and Konishi (2007) Plotosaurus (?) sp. NSM-PV15003 haemal arch Plotosaurus Russellosaurina Russellosaurina 1985 HMG-11 1994 HMG-371 HMG-371 Tylosaurus NSM-PV15003 HMG-1075HMG-1076HMG-1077 HMG-1075 HMG-1075 Mosasauridae, gen. et sp. indet. caudal vertebra intermediate region 4 ConiasianMaastrichtian 1985-011 1985 4 7 2 The Bulletin of the Hobetsu Museum, no. 23, March 2008
20042005 3 1 Mosasauridae intermediate region 20 30 Russell1967 Plioplatecarpinae Tylosaurinae HMG-1076 HMG-1076 Mosasauridae gen. et sp. indet. caudal vertebra pygal4 CampanianMaastrichtian 1994-003 1994 3 13 20042005 4 2 Mosasauridae pygal 30 Russell1967 ClidastesPlotosaurusPlatecarpusTylosaurusM.conodon M.conodonPlatecarpus Ectenosaurus Mosasauridae gen. et sp. indet. HMG-1077 HMG-1077 Mosasaurus sp. cf. M. hobetsuensis pterygoid tooth 5(?) prefrontal (?)? 1 splenial1 dentary1 ulnare1 Campanian?Maastrichtian? 1997-031 1997 10 21 20042005 4 1 35 2 4 1 4 5 Mosasauridae?? supraorbital process 6 7 V U angular mandibular channel Russell1967 1/3 8 HMG-12 intermedium The Bulletin of the Hobetsu Museum, no. 23, March 2008. 3
HMG-371Tylosaurus? sp.m Mosasaurus hobetsuensis HMG-12 M.hobetsuensis HMG-12 Mosasaurus sp. cf. M. hobetsuensis HMG-10 HMG-10 Mosasaurinae gen. et sp. indet. intermediate region17 1 1 1 Maastrichitian 199-123 1994 9 14 1980 9 20 19841985a19902005 1985a Mosasauridae Russell, 1967 Russell, 1967 2.5 30 Russell1967 Mosasaurinae ClidastesPlotosaurusPlatecarpus TylosaurusM.conodon 1985a Mosasaurinae HMG-11 HMG-11 Plioplatecarapinae? gen. et sp. indet. premaxilla 1 maxilla 2 marginal tooth1 angular1 atlas 1 cervical vertebra1 Coniasian Santonian1985a 1982-196 1982 11 17 1982 10 31 1985a198719902005 1985a narial opening internarial bar atlas centrum atlas intercentrum atlas neural arch atlas synapophysis 4 The Bulletin of the Hobetsu Museum, no. 23, March 2008
hypapophysis Mosasauridae Russell1967, p.74 Platecarpus hypapophysis hypapophysis zygospene zygontrum Russell (1967) ClidastesMosasaurusEctenosaurus Clidastes EctenosaurusMosasaurus GlobidensPlatecarpus EctenosaurusPlioplatecarpus zygospene zygontru Clidastes Ectenosaurus 1985a Plioplatecarpina? gen. et sp. indet. Mosasaurinae Dr. Caldwell Platecarpus Platecarpus 1985a Plioplatecarpinae? gen. et sp. indet. HMG-370 HMG-370 Mosasaurinae gen. et sp. indet. cervical vertebra 1 Santonian 1985a 1984-082 1984 10 28 1984 9 1985a198719902005 1985a hypapophysis Mosasauridae 1/2 Russell, 1967 zygosphene zygantrum (3) Russell (1967) ClidastesMosasaurusTylosaurus 1985a Mosasauridae gen. et sp. indet Mosasaurinae Caldwell, Mosasaurinae gen. et sp. indet. HMG-371 HMG-371 Tylosaurs sp. parietal 1 jugal1 pterygoid pterygoid teeth 3 marginal teeth 6anterior mandibular unit splenialdentary posterior mandibular unitangular surangularprearticular articular basisphenoid basioccipitaldorsal vertebra? 1 disit 1 Campanian1991 1985-053 1985 9 23 1985 9 22 1987199019941991 2005 1994 1994 parietal foramen overlap ectpterygoidal process The Bulletin of the Hobetsu Museum, no. 23, March 2008. 5
alar process ectpterygoidal basipterygoid process process basipterygoid process parasphenoid rostrum alar process occipital condyle basioccipital tuber basioccipital tuber basisphenoid neural arch hypapophysis perpendicular keel 1994 Tylosaurus mandibular channel prearticular anterior blade Tylosaurus sp Dr. Caldwell Tylosaurus coronoid Caldwell and Konishi, 2007Caldwell Russell1967; p.177, Text-fig.95 Williston1898; Pl.XVI Tylosarus Tylosaurs sp. HMG-1065 HMG-1065 meckelion fossa Mosasaurus prismaticus Sakurai, Chitoku and glenoid fossa Shibuya, 1999 marginal teeth1 parietal anterior blade 1 basioccipital basisphenoid parasphenoid - ophisthotic-exoccipital prootic supratemporal(?) epipterygoid?1 glenoid fossa rectangular process CampanianMaastrichtian 1995-015 1995 4 25 meckelion fossa 6 The Bulletin of the Hobetsu Museum, no. 23, March 2008
1995 4 25 19992005 (2) 1999 parietal foramen table occipital unit spraoccipital (?) Mosasaurus M. hobetsuensis 1999 Mosasaurus HMG-12 HMG-12 Mosasaurus hobetsuensis Suzuki, 1985 marginal tooth1 dorsal vertebra 10 dorsal rib 23 14 8 1 coracoid1 scapula1 forelimb 1 interclavicle 1(?) clavicle? 1 carpus 1 metacarpals1 phalanges 6 Maastrichtian 1982-199 1982 11 20 1982 11 20 19841985ab19871990 2005 1985b 1985b M.conodon M.conodon M.missouriensis M.conodon M.missouriensis Lingham-Soliar1995HMG-12 Leiodon Dr. Caldwell Caldwell HMG-1077 Mosasaurus HMG-1075HMG-1076 HMG-1077 Mosasaurus Mosasaurinae University of Alberta Dr. Caldwell 2006 Dr. Caldwell Sternberg Museum Dr. Everhart 2002 HMG-1065 HMG-12 The Bulletin of the Hobetsu Museum, no. 23, March 2008. 7
Caldwell, M.W. and Konishi, T, 2007, Taxonomic re-assignment of the first-known mosasaur specimen from Japan, and a discussion of circum-pacific mosasaur paleobiogeography. Journal of Vertebrate Paleontology 27(2): 517-520. 1990 6p.25-35 1994 10p.39-54 1993 9p.29-36pl.2 1991 7p.9-14pl.2 1986 3 p.1-7pl.3 Lingham-Soliar, T, 1995, The mosasaur Leiodon bares its teeth. in Sarjeant, W.A.S. ed. Vertebrate Fossils and the Evolution of Scientific Concepts. p.483-498. 1972 5p.213-223 2007 p.155-177 Russell, D.A., 1967, Systematics and morphology of American mosasaurs. Bulletin of the Peabody Museum of Natural History 23:1-241. 2005 21p.17-47 1999 Mosasaurus 15p.53-66 2004 - - 111 P-186 1984 1p.47-52 1985a 2p.31-42 pl.4 1985b Mosasaurus 30p.45-66 Williston, S.W., 1898, Mosasaurs. University of Kansas Geological Survey, 4, p.83-221, pls.10-82. 200823 1-11 Kazuhiko SAKURAI, 2008. A review of the mosasaur fossils from Hobetsu and around area. The Bulletin of the Hobetsu Museum, 23, 1-11. HMG-1075HMG-1076HMG-1077 1972 1982 1985ab1994 1999 9 7 8 The Bulletin of the Hobetsu Museum, no. 23, March 2008
穂 別 とその 周 辺 地 域 のモササウルス 化 石 の 再 検 討 b a a b 図 1 HMG-1075 産 出 部 位 断 片 的 な 尾 椎 ( 中 位 部 )の 椎 体 3 点 と, 分 離 したV 字 骨 の 遠 位 部 からなる. (a,b:hmg-1075を 異 なった 方 向 から 見 る) Fig.1 Preserved portion of HMG-1075 Three fragmental caudal vertebra (intermedial region) and an isolated chevron (distal portion). (a, b: different view of HMG-1075) a a b 図 2 HMG-1076 産 出 部 位 断 片 的 な 尾 椎 ( 基 部 )の 椎 体 3 点 と, 断 片 的 な 横 突 起 からなる. (a,b:hmg-1075を 異 なった 方 向 から 見 る) Fig.2 Preserved portion of HMG-1076 Three fragmental caudal vertebra (pygal) and a fragment of transverce process. (a, b: different view of HMG-1076) The Bulletin of the Hobetsu Museum, no.23, March 2008 9 b
櫻 井 和 彦 図 3 HMG-1077 産 出 部 位 ( 翼 状 骨 歯 ) 分 離 した 翼 状 骨 歯 の 歯 冠 部 4 点. Fig.3 Preserved portion of HMG-1077 (pterygoid tooth) Four isolated pterygoid teeth (crown). 図 4 HMG-1077 産 出 部 位 ( 翼 状 骨 歯 ) 4 点 の 翼 状 骨 歯 のうち, 最 も 保 存 状 態 の 良 い 歯. Fig.4 Preserved portion of HMG-1077 (pterygoid tooth) One of the pterygoid teeth (the best condition). 図 5 HMG-1077 産 出 部 位 ( 翼 状 骨 歯 ) 単 独 の 翼 状 骨 歯.ほぼ 完 全 な 歯 根 と 輪 郭 状 の 歯 からなる. Fig.5 Preserved portion of HMG-1077 (pterygoid tooth) An isolated pterygoid tooth (nearly complete root and outline of crown). p? a b 図 6 HMG-1077 産 出 部 位 ( 前 前 頭 骨?) 分 離 した 前 前 頭 骨?( 右?).a- 外 側 観,b- 内 側 観.p?: supraorbital process? Fig.6 Preserved portion of HMG-1077 (prefrontal?) Isolated prefrontal? (R?). a-lateral, b-medial. p?: supraorbital process? 10 The Bulletin of the Hobetsu Museum, no.23, March 2008
穂 別 とその 周 辺 地 域 のモササウルス 化 石 の 再 検 討 a b c 図 7 HMG-1077 産 出 部 位 ( 下 顎 前 位 部 ) 部 分 的 な 夾 板 骨 ( 左 )と 歯 骨 ( 左 ). a- 夾 板 骨,b- 歯 骨,c- 重 ね 合 わせた 状 態 ( 本 来 の 接 合 状 態 ). 全 て 外 側 観. Fig.7 Preserved portion of HMG-1077 (anterior mandibular unit) Partial splenial (L) and dentary (L). a-splenial, b-dentary, c-dentary on splenial. All phots are lateral view. a b c 図 8 HMG-1077 産 出 部 位 ( 尺 腕 骨 ) 一 部 を 欠 損 する 尺 腕 骨 ( 右 ).HMG-12(Mosasaurus hobetsuensis Suzuki, 1985 模 式 標 本 )のものに 類 似 する. a- 内 側 観,b- 外 側 観,c- 遠 位 観 ( 写 真 下 方 が 外 側 ) Fig.8 Preserved portion of HMG-1077 (ulnare) Partially lacked ulnare (R). Similar to one in HMG-12 (Holotype of Mosasaurus hobetsuensis Suzuki, 1985). a-medial, b-lateral, c-distal (lower is lateral) The Bulletin of the Hobetsu Museum, no.23, March 2008 11