Bull. Kitakyushu Mus. Nat. Hist. Hum. Hist., Ser. A, 19: 35–39, March 31, 2021 35

New record of a rostrum of waterbird (Aves, Suliformes) from the Oligocene of (Fig. 1). The horizon that yielded the specimen consists of fine Hasegawa, 1979, 1996; Olson, 1980; Mayr, 2005; Sakurai et with a comprehensive comparison among water . Ozaki, M., Hamasaki, S. and Yoshii, M. 1993. Geology of the Tomita, T. and Oji, T. 2010. Habitat reconstruction of sandstone marked by cross-stratification, including nodules, al., 2008; Smith, 2010; Mayr et al., 2015). On the other hand, Zoological Journal of the Linnean Society, 170: 467–493. Orio district. With Geological Sheet Map at 1:50000. Oligocene elasmobranchs from Yamaga Formation, Ashiya Group in Ainoshima Island, Kyushu, Japan and has produced abundant remains of marine molluscs and there is much evidence of similarity between and Knoll, F. and Kawabe, S. 2020. Avian palaeoneurology: Geological Survey of Japan, Tsukuba. Ashiya Group, Western Japan. Paleontological Research, shark teeth (Fig. 2). Stratigraphically, the type horizon belongs Sphenisciformes (Mayr, 2005; Kawabe et al., 2014; Mayr et reflections on the eve of its 200th anniversary. Journal of Sakakura, N. 2002. Taphonomy of the bivalve assemblages in 14: 69–80. Soichiro Kawabe1, Yusuke Ando2, Shigenori Kawano3 and Kumiko Matsui4 to the Yamaga Formation, which in turn forms the lowermost al., 2015), and although the phylogenetic relationship between , 236: 965–979. the upper part of the Paleogene Ashiya Group, southwest- Uyeno, T., Yabumoto, Y. and Kuga, N. 1984. Fossil fishes of part of the Ashiya Group (Ozaki et al., 1993; Nakae et al., them is controversial, this study concludes that KMNH VP Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, ern Japan. Paleontological Research, 6: 101–120. Ashiya Group – (1); Late Oligocene elasmobranchs from 1998). The group is widely distributed in the northern area of 600013 is tentatively a member of Suliformes, taking into Tenth Edition, 2 Volumes. L. Salvii, Stockholm. Sakurai, K., Kimura, M. and Katoh, T. 2008. A new - Island of Ainoshima and Kaijima Kitakyushu. Bulletin of 1Fukui Prefectural University, 4-1-1 Matsuokakenjojima, Eiheiji-cho, 910-1195 Fukui, Japan Fukuoka Prefecture and consists mostly of shallow marine account the possibility that it belongs to Plotopteridae. Mayr, G. 2005. Tertiary plotopterids (Aves, Plotopteridae) and like (: Plotopteridae) from the Late the Kitakyushu Museum of Natural History, 5: 135–142. 2Mizunami Fossil Museum, 1-47 Yamanouchi, Akeyo, Mizunami City, 509-6132 Gifu, Japan deposits rich in molluscs (e.g., Sakakura, 2002), crabs (e.g., a novel hypothesis on the phylogenetic relationships of Oligocene Tokoro Formation, northeastern Hokkaido, 3Tochigi Prefectural Museum, 2-2 Mutumi, Utsunomiya City, 320-0865 Tochigi, Japan Kato and Karasawa 1994; Ando and Karasawa 2010), shark (Spheniscidae). Journal of Zoological Systematics Japan. Oryctos, 7: 83–94. 4 The Kyushu University Museum, 6-10-1 Hakozaki, Higashi-ku, Fukuoka City, 812-8581 Fukuoka, Japan teeth (e.g., Uyeno et al., 1984; Tomita and Oji, 2010), marine ACKNOWLEDGEMENTS and Evolutionary Research, 43: 61–71. Smith, N. D. 2010. Phylogenetic analysis of Pelecaniformes mammals (Okazaki, 1984, 2012) and birds (e.g., Hasegawa et Mayr, G., Goedert, J. L. and Vogel, O. 2015. Oligocene (Aves) based on osteological data: implications for (Received June 8, 2020; accepted September 10, 2020) al., 1979; Okazaki 1989; Olson and Hasegawa, 1996). The age We thank Daisuke Nakatani (Nagasaki City) for helping plotopterid skulls from western North America and their waterbird phylogeny and fossil calibration studies. PLoS of the Yamaga Formation is the latest Early Oligocene with our fieldwork. We also thank Yoshikazu Hasegawa bearing on the phylogenetic affinities of these ONE, 5: e13354. DOI: 10.1371/journal.pone.0013354 (CP19a), based on calcareous nannofossil and planktonic (Gunma Museum of Natural History) and Hiroaki Karasawa penguin-like . Journal of Vertebrate Paleontology, ABSTRACT − A rostrum of a suliform bird from the Lower Oligocene Yamaga Formation of Ashiya Group in Ainoshima Island, Fukuoka Prefecture, Kyushu, southwestern Japan is briefly described. The present foraminiferal evidence (Okada and Bukry, 1980; Okada, 1992; (Mizunami Fossil Museum) for useful discussions, and Karin 35: e943764. DOI: 10.1080/02724634.2014.943764 specimen (KMNH VP 600013) is slender and flat, with a strongly curved rostral tip, a sharply-defined Ibaraki, 1994). Iwasa (Naniwa-Honehone-Dan) for providing images of extant Nakae, S., Ozaki, M., Ota, M., Yabumoto, Y., Matsuura, H. longitudinal groove, and apertura nasi ossea that were likely extremely reduced or absent. Institutional Abbreviations — KMNH: Kitakyushu Museum phalacrocoracids. This manuscript was greatly improved by and Tomita, S. 1998. Geology of the Kokura district. With of Natural History and Human History, Kitakyushu, Japan. comments from Nathan D. Smith (Natural History Museum of Geological Sheet Map at 1:50000. Geological Survey of KEY WORDS: Kitakyushu City, East Asia, Early Oligocene, Suliformes, premaxilla Los Angeles County), and an anonymous reviewer. Japan, Tsukuba. Okada, H. 1992. Calcareous nannofossils and biostratigraphy SYSTEMATIC PALAEONTOLOGY of the Paleogene sequences of northern Kyushu, Japan. REFERENCES Journal of the Geological Society of Japan, 98: 505–528. Aves Linnaeus, 1758 Okada, H. and Bukry, D. 1980. Supplementary modification Suliformes sensu Chesser et al., 2010 Ando, Y. and Karasawa, H. 2010. Mud shrimp associated with and introduction of code numbers to the low-latitude INTRODUCTION burrows from the Oligocene Ashiya Group, northern Coccolith biostratigraphic Zonation (Bukry, 1973; 1975). Material. KMNH VP 600013, almost complete Kyushu, Japan, with description of a new of Marine Micropaleontology, 5: 321–325. The Oligocene Ashiya Group is rich in marine inverte- premaxillae (Fig. 3). Upogebia (Decapoda: Gebiidea). Zootaxa, 2337: 63–68. Okazaki, Y. 1984. An occurrence of fossil sirenia (Mammalia) brate and vertebrate fossils (e.g., Hasegawa et al., 1979; Uyeno Locality and Horizon. The western coast of Ainoshima Chesser, R. T., Banks, R. C., Barker, F. K., Cicero, C., Dunn, from the Ashiya Group, Kyushu, Japan. Bulletin of the et al., 1984; Okazaki, 1984, 1989, 2012; Kato and Karasawa, Island, Kitakyushu City, Fukuoka Prefecture, Japan; Yamaga J. L., Kratter, A. W., Lovette, I. J., Rasmussen, P. C., Kitakyushu Museum of Natural History, 5: 189–195, pls. 1996; Olson and Hasegawa, 1996; Sakakura, 2002; Ando and Formation, Ashiya Group, Early Oligocene. Remsen, JR. J. V., Rising, J. D., Stotz, D. F. and Winker, 8–9. Karasawa, 2010; Tomita and Oji, 2010). Although many avian Measurements. Length: 88.0 mm; maximum height: 8.3 K. 2010. Fifty-first Supplement to the American Okazaki, Y. 1989. An occurrence of fossil bony-toothed bird fossils have been collected and studied from this group (e.g., mm; maximum width: 12.1 mm. Ornithologists' Union check-list of North American birds. (Odontopterygiformes) from the Ashiya Group (Oligo- Okazaki 1989; Olson and Hasegawa, 1996; Kawabe et al., Description. The rostrum is relatively slender, elongate The Auk, 127: 726–744. cene), Japan. Bulletin of the Kitakyushu Museum of Natu- 2014; Knoll and Kawabe, 2020), no rostrum has been triangular in dorsal view, and flat with little variation in slender rostrum with little variation in dorsoventral depth is indeterminate plotopterid (Suliformes) (KMNH VP 200008) Cracraft, J. 1985. Monophyly and phylogenetic relationships ral History, 9: 123–126. described. Kawabe et al. (2014) and Knoll and Kawabe (2020) dorsoventral depth throughout. The cross-section of the mainly found in . Furthermore, the strongly curved (Kawabe et al., 2014) discovered from the Ashiya Group of the Pelecaniformes: A numerical cladistic analysis. The Okazaki, Y. 2012. A new mysticete from the upper Oligocene showed a photograph and CG image of the entire skull of rostrum is triangular and gradually becomes smaller from tip is a characteristic of Procellariiformes, Scopus, , (upper Oligocene) in Touno, Kitakyushu City. The rostrum of Auk, 102: 834–853. Ashiya Group, Kyushu, Japan and its significance to indeterminate plotopterid (Suliformes) (KMNH VP 200008) caudal to rostral end. The dorsal and ventral margins of the and cormorants (Smith, 2010), and KMNH VP 600013 is the Touno specimen (KMNH VP 200008) is relatively well Hasegawa, Y., Isotani, S., Nagai, K., Seki, K., Suzuki, T., mysticete . Bulletin of the Kitakyushu Museum of found in the Ashiya Group, but a detailed osteological posterior portion are straight, and the rostral tip is pointed and similar to that of cormorants. However, KMNH VP 600013 preserved, but has been deformed and damaged, and the Otsuka, H., Ota, M. and Ono, K. 1979. Preliminary notes Natural History and Human History, Ser. A (Natural description of this specimen has not been made. Since the strongly curved to form a ventrally directed hook. Laterally, differs from cormorants in having a lateral groove on the preparation has not been completed, so detailed aspects of its on the Oligo-Miocene penguin-like birds from Japan. History), 10: 129–152. rostrum of KMNH VP 200008 was heavily deformed and each premaxilla bears a sharply-defined longitudinal groove, premaxilla that does not reach the crista tomialis. The posterior morphology are unknown. However, the rostrums of KMNH Bulletin of the Kitakyushu Museum of Natural History, 1: Olson, S. L. 1980. A new of penguin-like pelecaniform further physical preparation was difficult, the information on flanked on either side by a series of foramina neurovascularia part of KMNH VP 600013 is not fully preserved. However, the VP 600013 and the Touno specimen are morphologically very 41–60. bird from the Oligocene of Washington (Pelecaniformes: the avian rostrum found in the Ashiya Group is hardly and accompanied shallow sulci. Just posterior to the terminal dorsoventral depth of KMNH VP 600013 varies little similar in that they are slender and have strong longitudinal Ibaraki, M. 1994. Age and paleoenvironments of Tertiary in Plotopteridae). Natural History Museum of Los Angeles available. We collected a well-preserved avian rostrum from hook, this groove descends towards, but never actually throughout rostral to caudal, and does not provide sufficient grooves and strongly curved tips. Additionally, KMNH VP northwestern Kyushu on the basis of planktonic County, Contributions in Science, 330: 51–57. the Lower Oligocene Yamaga Formation of Ashiya Group in reaches, the crista tomialis. In ventral view, the premaxillae are space for the apertura nasi ossea, suggesting that the apertura 600013 also shows morphological similarity with another foraminifers. Monthly Chikyu, 16: 150–153. Olson, S. L. and Hasegawa, Y. 1979. Fossil counterparts of Ainoshima Island, Kitakyushu City, Japan. This is the first fused along the midline and form a slightly concave palatal nasi ossea are absent or extremely diminished. The extremely protopterid Tonsala hildegardae (SMF Av 599) from the Kato, H. and Karasawa, H. 1994. Minohellenus macrocheilus giant penguins from the North Pacific. Science, 206: record of a complete and extremely well-preserved avian LOCALITY AND GEOLOGICAL SETTING surface. reduced apertura nasi ossea are considered to be one of the Oligocene Pysht Formation of Washington State, U.S.A., in sp. nov. (Decapoda: Crustacea) from the Oligocene 688–689. rostrum from the Paleogene in Kyushu and the purpose of the Remarks. KMNH VP 600013 is characterized by being synapomorphies of Suloidea sensu Cracraft (1985) (Smith, having distinct longitudinal grooves and subsequent very Ashiya Group, Kyushu, Japan. Bulletin of the Kitakyushu Olson, S. L. and Hasegawa, Y. 1996. A new genus and two present paper is to provide a brief description of the newly The new material was retrieved from a sea cliff on the slender and flat, having a strongly curved tip, and a 2010), and therefore KMNH VP 600013 likely belongs to reduced slit-like apertura nasi ossea (Mayr et al., 2015). Museum of Natural History, 13: 51–58. new species of gigantic Plotopteridae from Japan (Aves: western coast of Ainoshima Island, 10 km north of Kitakyushu sharply-defined longitudinal groove. Most of these features are Suliformes. Osteological and phylogenetic studies have demonstrated the Kawabe, S., Ando, T. and Endo, H. 2014. Enigmatic affinity in Pelecaniformes). Journal of Vertebrate Paleontology, 16: collected material. Fig. 1. Map showing the present fossil locality. City, Fukuoka Prefecture, Japan (33° 59′ 27″ N, 130° 48′ 58″ E) generally found in Suliformes and Procellariiformes, but the KMNH VP 600013 also resembles a specimen of close affinity between Plotopteridae and Suloidea (Olson and the brain morphology between plotopterids and penguins, 742–751. 36 Soichiro Kawabe, Yusuke Ando, Shigenori Kawano and Kumiko Matsui A rostrum of waterbird from Ainoshima Island, Japan 37

(Fig. 1). The horizon that yielded the specimen consists of fine Hasegawa, 1979, 1996; Olson, 1980; Mayr, 2005; Sakurai et with a comprehensive comparison among water birds. Ozaki, M., Hamasaki, S. and Yoshii, M. 1993. Geology of the Tomita, T. and Oji, T. 2010. Habitat reconstruction of sandstone marked by cross-stratification, including nodules, al., 2008; Smith, 2010; Mayr et al., 2015). On the other hand, Zoological Journal of the Linnean Society, 170: 467–493. Orio district. With Geological Sheet Map at 1:50000. Oligocene elasmobranchs from Yamaga Formation, and has produced abundant remains of marine molluscs and there is much evidence of similarity between Plotopteridae and Knoll, F. and Kawabe, S. 2020. Avian palaeoneurology: Geological Survey of Japan, Tsukuba. Ashiya Group, Western Japan. Paleontological Research, shark teeth (Fig. 2). Stratigraphically, the type horizon belongs Sphenisciformes (Mayr, 2005; Kawabe et al., 2014; Mayr et reflections on the eve of its 200th anniversary. Journal of Sakakura, N. 2002. Taphonomy of the bivalve assemblages in 14: 69–80. to the Yamaga Formation, which in turn forms the lowermost al., 2015), and although the phylogenetic relationship between Anatomy, 236: 965–979. the upper part of the Paleogene Ashiya Group, southwest- Uyeno, T., Yabumoto, Y. and Kuga, N. 1984. Fossil fishes of part of the Ashiya Group (Ozaki et al., 1993; Nakae et al., them is controversial, this study concludes that KMNH VP Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, ern Japan. Paleontological Research, 6: 101–120. Ashiya Group – (1); Late Oligocene elasmobranchs from 1998). The group is widely distributed in the northern area of 600013 is tentatively a member of Suliformes, taking into Tenth Edition, 2 Volumes. L. Salvii, Stockholm. Sakurai, K., Kimura, M. and Katoh, T. 2008. A new penguin- Island of Ainoshima and Kaijima Kitakyushu. Bulletin of Fukuoka Prefecture and consists mostly of shallow marine account the possibility that it belongs to Plotopteridae. Mayr, G. 2005. Tertiary plotopterids (Aves, Plotopteridae) and like bird (Pelecaniformes: Plotopteridae) from the Late the Kitakyushu Museum of Natural History, 5: 135–142. deposits rich in molluscs (e.g., Sakakura, 2002), crabs (e.g., a novel hypothesis on the phylogenetic relationships of Oligocene Tokoro Formation, northeastern Hokkaido, Kato and Karasawa 1994; Ando and Karasawa 2010), shark penguins (Spheniscidae). Journal of Zoological Systematics Japan. Oryctos, 7: 83–94. teeth (e.g., Uyeno et al., 1984; Tomita and Oji, 2010), marine ACKNOWLEDGEMENTS and Evolutionary Research, 43: 61–71. Smith, N. D. 2010. Phylogenetic analysis of Pelecaniformes mammals (Okazaki, 1984, 2012) and birds (e.g., Hasegawa et Mayr, G., Goedert, J. L. and Vogel, O. 2015. Oligocene (Aves) based on osteological data: implications for al., 1979; Okazaki 1989; Olson and Hasegawa, 1996). The age We thank Daisuke Nakatani (Nagasaki City) for helping plotopterid skulls from western North America and their waterbird phylogeny and fossil calibration studies. PLoS of the Yamaga Formation is the latest Early Oligocene with our fieldwork. We also thank Yoshikazu Hasegawa bearing on the phylogenetic affinities of these ONE, 5: e13354. DOI: 10.1371/journal.pone.0013354 (CP19a), based on calcareous nannofossil and planktonic (Gunma Museum of Natural History) and Hiroaki Karasawa penguin-like seabirds. Journal of Vertebrate Paleontology, foraminiferal evidence (Okada and Bukry, 1980; Okada, 1992; (Mizunami Fossil Museum) for useful discussions, and Karin 35: e943764. DOI: 10.1080/02724634.2014.943764 Ibaraki, 1994). Iwasa (Naniwa-Honehone-Dan) for providing images of extant Nakae, S., Ozaki, M., Ota, M., Yabumoto, Y., Matsuura, H. Institutional Abbreviations — KMNH: Kitakyushu Museum phalacrocoracids. This manuscript was greatly improved by and Tomita, S. 1998. Geology of the Kokura district. With of Natural History and Human History, Kitakyushu, Japan. comments from Nathan D. Smith (Natural History Museum of Geological Sheet Map at 1:50000. Geological Survey of Los Angeles County), and an anonymous reviewer. Japan, Tsukuba. Okada, H. 1992. Calcareous nannofossils and biostratigraphy SYSTEMATIC PALAEONTOLOGY of the Paleogene sequences of northern Kyushu, Japan. REFERENCES Journal of the Geological Society of Japan, 98: 505–528. Class Aves Linnaeus, 1758 Okada, H. and Bukry, D. 1980. Supplementary modification Order Suliformes sensu Chesser et al., 2010 Ando, Y. and Karasawa, H. 2010. Mud shrimp associated with and introduction of code numbers to the low-latitude INTRODUCTION burrows from the Oligocene Ashiya Group, northern Coccolith biostratigraphic Zonation (Bukry, 1973; 1975). Material. KMNH VP 600013, almost complete Kyushu, Japan, with description of a new species of Marine Micropaleontology, 5: 321–325. The Oligocene Ashiya Group is rich in marine inverte- premaxillae (Fig. 3). Upogebia (Decapoda: Gebiidea). Zootaxa, 2337: 63–68. Okazaki, Y. 1984. An occurrence of fossil sirenia (Mammalia) brate and vertebrate fossils (e.g., Hasegawa et al., 1979; Uyeno Locality and Horizon. The western coast of Ainoshima Chesser, R. T., Banks, R. C., Barker, F. K., Cicero, C., Dunn, from the Ashiya Group, Kyushu, Japan. Bulletin of the et al., 1984; Okazaki, 1984, 1989, 2012; Kato and Karasawa, Island, Kitakyushu City, Fukuoka Prefecture, Japan; Yamaga Fig. 3. Suliform rostrum, KMNH VP 600013. A, left lateral view; B, right lateral view; C, dorsal view; and D, ventral view. Scale J. L., Kratter, A. W., Lovette, I. J., Rasmussen, P. C., Kitakyushu Museum of Natural History, 5: 189–195, pls. 1996; Olson and Hasegawa, 1996; Sakakura, 2002; Ando and Formation, Ashiya Group, Early Oligocene. bar = 10 mm. Remsen, JR. J. V., Rising, J. D., Stotz, D. F. and Winker, 8–9. Karasawa, 2010; Tomita and Oji, 2010). Although many avian Measurements. Length: 88.0 mm; maximum height: 8.3 K. 2010. Fifty-first Supplement to the American Okazaki, Y. 1989. An occurrence of fossil bony-toothed bird fossils have been collected and studied from this group (e.g., mm; maximum width: 12.1 mm. Ornithologists' Union check-list of North American birds. (Odontopterygiformes) from the Ashiya Group (Oligo- Okazaki 1989; Olson and Hasegawa, 1996; Kawabe et al., Description. The rostrum is relatively slender, elongate The Auk, 127: 726–744. cene), Japan. Bulletin of the Kitakyushu Museum of Natu- 2014; Knoll and Kawabe, 2020), no rostrum has been triangular in dorsal view, and flat with little variation in slender rostrum with little variation in dorsoventral depth is indeterminate plotopterid (Suliformes) (KMNH VP 200008) Cracraft, J. 1985. Monophyly and phylogenetic relationships ral History, 9: 123–126. described. Kawabe et al. (2014) and Knoll and Kawabe (2020) dorsoventral depth throughout. The cross-section of the mainly found in cormorants. Furthermore, the strongly curved (Kawabe et al., 2014) discovered from the Ashiya Group of the Pelecaniformes: A numerical cladistic analysis. The Okazaki, Y. 2012. A new mysticete from the upper Oligocene showed a photograph and CG image of the entire skull of rostrum is triangular and gradually becomes smaller from tip is a characteristic of Procellariiformes, Scopus, frigatebirds, (upper Oligocene) in Touno, Kitakyushu City. The rostrum of Auk, 102: 834–853. Ashiya Group, Kyushu, Japan and its significance to indeterminate plotopterid (Suliformes) (KMNH VP 200008) caudal to rostral end. The dorsal and ventral margins of the and cormorants (Smith, 2010), and KMNH VP 600013 is the Touno specimen (KMNH VP 200008) is relatively well Hasegawa, Y., Isotani, S., Nagai, K., Seki, K., Suzuki, T., mysticete evolution. Bulletin of the Kitakyushu Museum of found in the Ashiya Group, but a detailed osteological posterior portion are straight, and the rostral tip is pointed and similar to that of cormorants. However, KMNH VP 600013 preserved, but has been deformed and damaged, and the Otsuka, H., Ota, M. and Ono, K. 1979. Preliminary notes Natural History and Human History, Ser. A (Natural description of this specimen has not been made. Since the strongly curved to form a ventrally directed hook. Laterally, differs from cormorants in having a lateral groove on the preparation has not been completed, so detailed aspects of its on the Oligo-Miocene penguin-like birds from Japan. History), 10: 129–152. rostrum of KMNH VP 200008 was heavily deformed and each premaxilla bears a sharply-defined longitudinal groove, premaxilla that does not reach the crista tomialis. The posterior morphology are unknown. However, the rostrums of KMNH Bulletin of the Kitakyushu Museum of Natural History, 1: Olson, S. L. 1980. A new genus of penguin-like pelecaniform further physical preparation was difficult, the information on flanked on either side by a series of foramina neurovascularia part of KMNH VP 600013 is not fully preserved. However, the VP 600013 and the Touno specimen are morphologically very 41–60. bird from the Oligocene of Washington (Pelecaniformes: the avian rostrum found in the Ashiya Group is hardly Fig. 2. Stratigraphic column showing the stratigraphic position and accompanied shallow sulci. Just posterior to the terminal dorsoventral depth of KMNH VP 600013 varies little similar in that they are slender and have strong longitudinal Ibaraki, M. 1994. Age and paleoenvironments of Tertiary in Plotopteridae). Natural History Museum of Los Angeles available. We collected a well-preserved avian rostrum from of KMNH VP 600013. hook, this groove descends towards, but never actually throughout rostral to caudal, and does not provide sufficient grooves and strongly curved tips. Additionally, KMNH VP northwestern Kyushu on the basis of planktonic County, Contributions in Science, 330: 51–57. the Lower Oligocene Yamaga Formation of Ashiya Group in reaches, the crista tomialis. In ventral view, the premaxillae are space for the apertura nasi ossea, suggesting that the apertura 600013 also shows morphological similarity with another foraminifers. Monthly Chikyu, 16: 150–153. Olson, S. L. and Hasegawa, Y. 1979. Fossil counterparts of Ainoshima Island, Kitakyushu City, Japan. This is the first fused along the midline and form a slightly concave palatal nasi ossea are absent or extremely diminished. The extremely protopterid Tonsala hildegardae (SMF Av 599) from the Kato, H. and Karasawa, H. 1994. Minohellenus macrocheilus giant penguins from the North Pacific. Science, 206: record of a complete and extremely well-preserved avian LOCALITY AND GEOLOGICAL SETTING surface. reduced apertura nasi ossea are considered to be one of the Oligocene Pysht Formation of Washington State, U.S.A., in sp. nov. (Decapoda: Crustacea) from the Oligocene 688–689. rostrum from the Paleogene in Kyushu and the purpose of the Remarks. KMNH VP 600013 is characterized by being synapomorphies of Suloidea sensu Cracraft (1985) (Smith, having distinct longitudinal grooves and subsequent very Ashiya Group, Kyushu, Japan. Bulletin of the Kitakyushu Olson, S. L. and Hasegawa, Y. 1996. A new genus and two present paper is to provide a brief description of the newly The new material was retrieved from a sea cliff on the slender and flat, having a strongly curved tip, and a 2010), and therefore KMNH VP 600013 likely belongs to reduced slit-like apertura nasi ossea (Mayr et al., 2015). Museum of Natural History, 13: 51–58. new species of gigantic Plotopteridae from Japan (Aves: collected material. western coast of Ainoshima Island, 10 km north of Kitakyushu sharply-defined longitudinal groove. Most of these features are Suliformes. Osteological and phylogenetic studies have demonstrated the Kawabe, S., Ando, T. and Endo, H. 2014. Enigmatic affinity in Pelecaniformes). Journal of Vertebrate Paleontology, 16: City, Fukuoka Prefecture, Japan (33° 59′ 27″ N, 130° 48′ 58″ E) generally found in Suliformes and Procellariiformes, but the KMNH VP 600013 also resembles a specimen of close affinity between Plotopteridae and Suloidea (Olson and the brain morphology between plotopterids and penguins, 742–751. 36 Soichiro Kawabe, Yusuke Ando, Shigenori Kawano and Kumiko Matsui A rostrum of waterbird from Ainoshima Island, Japan 37

(Fig. 1). The horizon that yielded the specimen consists of fine Hasegawa, 1979, 1996; Olson, 1980; Mayr, 2005; Sakurai et with a comprehensive comparison among water birds. Ozaki, M., Hamasaki, S. and Yoshii, M. 1993. Geology of the Tomita, T. and Oji, T. 2010. Habitat reconstruction of sandstone marked by cross-stratification, including nodules, al., 2008; Smith, 2010; Mayr et al., 2015). On the other hand, Zoological Journal of the Linnean Society, 170: 467–493. Orio district. With Geological Sheet Map at 1:50000. Oligocene elasmobranchs from Yamaga Formation, and has produced abundant remains of marine molluscs and there is much evidence of similarity between Plotopteridae and Knoll, F. and Kawabe, S. 2020. Avian palaeoneurology: Geological Survey of Japan, Tsukuba. Ashiya Group, Western Japan. Paleontological Research, shark teeth (Fig. 2). Stratigraphically, the type horizon belongs Sphenisciformes (Mayr, 2005; Kawabe et al., 2014; Mayr et reflections on the eve of its 200th anniversary. Journal of Sakakura, N. 2002. Taphonomy of the bivalve assemblages in 14: 69–80. to the Yamaga Formation, which in turn forms the lowermost al., 2015), and although the phylogenetic relationship between Anatomy, 236: 965–979. the upper part of the Paleogene Ashiya Group, southwest- Uyeno, T., Yabumoto, Y. and Kuga, N. 1984. Fossil fishes of part of the Ashiya Group (Ozaki et al., 1993; Nakae et al., them is controversial, this study concludes that KMNH VP Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, ern Japan. Paleontological Research, 6: 101–120. Ashiya Group – (1); Late Oligocene elasmobranchs from 1998). The group is widely distributed in the northern area of 600013 is tentatively a member of Suliformes, taking into Tenth Edition, 2 Volumes. L. Salvii, Stockholm. Sakurai, K., Kimura, M. and Katoh, T. 2008. A new penguin- Island of Ainoshima and Kaijima Kitakyushu. Bulletin of Fukuoka Prefecture and consists mostly of shallow marine account the possibility that it belongs to Plotopteridae. Mayr, G. 2005. Tertiary plotopterids (Aves, Plotopteridae) and like bird (Pelecaniformes: Plotopteridae) from the Late the Kitakyushu Museum of Natural History, 5: 135–142. deposits rich in molluscs (e.g., Sakakura, 2002), crabs (e.g., a novel hypothesis on the phylogenetic relationships of Oligocene Tokoro Formation, northeastern Hokkaido, Kato and Karasawa 1994; Ando and Karasawa 2010), shark penguins (Spheniscidae). Journal of Zoological Systematics Japan. Oryctos, 7: 83–94. teeth (e.g., Uyeno et al., 1984; Tomita and Oji, 2010), marine ACKNOWLEDGEMENTS and Evolutionary Research, 43: 61–71. Smith, N. D. 2010. Phylogenetic analysis of Pelecaniformes mammals (Okazaki, 1984, 2012) and birds (e.g., Hasegawa et Mayr, G., Goedert, J. L. and Vogel, O. 2015. Oligocene (Aves) based on osteological data: implications for al., 1979; Okazaki 1989; Olson and Hasegawa, 1996). The age We thank Daisuke Nakatani (Nagasaki City) for helping plotopterid skulls from western North America and their waterbird phylogeny and fossil calibration studies. PLoS of the Yamaga Formation is the latest Early Oligocene with our fieldwork. We also thank Yoshikazu Hasegawa bearing on the phylogenetic affinities of these ONE, 5: e13354. DOI: 10.1371/journal.pone.0013354 (CP19a), based on calcareous nannofossil and planktonic (Gunma Museum of Natural History) and Hiroaki Karasawa penguin-like seabirds. Journal of Vertebrate Paleontology, foraminiferal evidence (Okada and Bukry, 1980; Okada, 1992; (Mizunami Fossil Museum) for useful discussions, and Karin 35: e943764. DOI: 10.1080/02724634.2014.943764 Ibaraki, 1994). Iwasa (Naniwa-Honehone-Dan) for providing images of extant Nakae, S., Ozaki, M., Ota, M., Yabumoto, Y., Matsuura, H. Institutional Abbreviations — KMNH: Kitakyushu Museum phalacrocoracids. This manuscript was greatly improved by and Tomita, S. 1998. Geology of the Kokura district. With of Natural History and Human History, Kitakyushu, Japan. comments from Nathan D. Smith (Natural History Museum of Geological Sheet Map at 1:50000. Geological Survey of Los Angeles County), and an anonymous reviewer. Japan, Tsukuba. Okada, H. 1992. Calcareous nannofossils and biostratigraphy SYSTEMATIC PALAEONTOLOGY of the Paleogene sequences of northern Kyushu, Japan. REFERENCES Journal of the Geological Society of Japan, 98: 505–528. Class Aves Linnaeus, 1758 Okada, H. and Bukry, D. 1980. Supplementary modification Order Suliformes sensu Chesser et al., 2010 Ando, Y. and Karasawa, H. 2010. Mud shrimp associated with and introduction of code numbers to the low-latitude INTRODUCTION burrows from the Oligocene Ashiya Group, northern Coccolith biostratigraphic Zonation (Bukry, 1973; 1975). Material. KMNH VP 600013, almost complete Kyushu, Japan, with description of a new species of Marine Micropaleontology, 5: 321–325. The Oligocene Ashiya Group is rich in marine inverte- premaxillae (Fig. 3). Upogebia (Decapoda: Gebiidea). Zootaxa, 2337: 63–68. Okazaki, Y. 1984. An occurrence of fossil sirenia (Mammalia) brate and vertebrate fossils (e.g., Hasegawa et al., 1979; Uyeno Locality and Horizon. The western coast of Ainoshima Chesser, R. T., Banks, R. C., Barker, F. K., Cicero, C., Dunn, from the Ashiya Group, Kyushu, Japan. Bulletin of the et al., 1984; Okazaki, 1984, 1989, 2012; Kato and Karasawa, Island, Kitakyushu City, Fukuoka Prefecture, Japan; Yamaga Fig. 3. Suliform rostrum, KMNH VP 600013. A, left lateral view; B, right lateral view; C, dorsal view; and D, ventral view. Scale J. L., Kratter, A. W., Lovette, I. J., Rasmussen, P. C., Kitakyushu Museum of Natural History, 5: 189–195, pls. 1996; Olson and Hasegawa, 1996; Sakakura, 2002; Ando and Formation, Ashiya Group, Early Oligocene. bar = 10 mm. Remsen, JR. J. V., Rising, J. D., Stotz, D. F. and Winker, 8–9. Karasawa, 2010; Tomita and Oji, 2010). Although many avian Measurements. Length: 88.0 mm; maximum height: 8.3 K. 2010. Fifty-first Supplement to the American Okazaki, Y. 1989. An occurrence of fossil bony-toothed bird fossils have been collected and studied from this group (e.g., mm; maximum width: 12.1 mm. Ornithologists' Union check-list of North American birds. (Odontopterygiformes) from the Ashiya Group (Oligo- Okazaki 1989; Olson and Hasegawa, 1996; Kawabe et al., Description. The rostrum is relatively slender, elongate The Auk, 127: 726–744. cene), Japan. Bulletin of the Kitakyushu Museum of Natu- 2014; Knoll and Kawabe, 2020), no rostrum has been triangular in dorsal view, and flat with little variation in slender rostrum with little variation in dorsoventral depth is indeterminate plotopterid (Suliformes) (KMNH VP 200008) Cracraft, J. 1985. Monophyly and phylogenetic relationships ral History, 9: 123–126. described. Kawabe et al. (2014) and Knoll and Kawabe (2020) dorsoventral depth throughout. The cross-section of the mainly found in cormorants. Furthermore, the strongly curved (Kawabe et al., 2014) discovered from the Ashiya Group of the Pelecaniformes: A numerical cladistic analysis. The Okazaki, Y. 2012. A new mysticete from the upper Oligocene showed a photograph and CG image of the entire skull of rostrum is triangular and gradually becomes smaller from tip is a characteristic of Procellariiformes, Scopus, frigatebirds, (upper Oligocene) in Touno, Kitakyushu City. The rostrum of Auk, 102: 834–853. Ashiya Group, Kyushu, Japan and its significance to indeterminate plotopterid (Suliformes) (KMNH VP 200008) caudal to rostral end. The dorsal and ventral margins of the and cormorants (Smith, 2010), and KMNH VP 600013 is the Touno specimen (KMNH VP 200008) is relatively well Hasegawa, Y., Isotani, S., Nagai, K., Seki, K., Suzuki, T., mysticete evolution. Bulletin of the Kitakyushu Museum of found in the Ashiya Group, but a detailed osteological posterior portion are straight, and the rostral tip is pointed and similar to that of cormorants. However, KMNH VP 600013 preserved, but has been deformed and damaged, and the Otsuka, H., Ota, M. and Ono, K. 1979. Preliminary notes Natural History and Human History, Ser. A (Natural description of this specimen has not been made. Since the strongly curved to form a ventrally directed hook. Laterally, differs from cormorants in having a lateral groove on the preparation has not been completed, so detailed aspects of its on the Oligo-Miocene penguin-like birds from Japan. History), 10: 129–152. rostrum of KMNH VP 200008 was heavily deformed and each premaxilla bears a sharply-defined longitudinal groove, premaxilla that does not reach the crista tomialis. The posterior morphology are unknown. However, the rostrums of KMNH Bulletin of the Kitakyushu Museum of Natural History, 1: Olson, S. L. 1980. A new genus of penguin-like pelecaniform further physical preparation was difficult, the information on flanked on either side by a series of foramina neurovascularia part of KMNH VP 600013 is not fully preserved. However, the VP 600013 and the Touno specimen are morphologically very 41–60. bird from the Oligocene of Washington (Pelecaniformes: the avian rostrum found in the Ashiya Group is hardly Fig. 2. Stratigraphic column showing the stratigraphic position and accompanied shallow sulci. Just posterior to the terminal dorsoventral depth of KMNH VP 600013 varies little similar in that they are slender and have strong longitudinal Ibaraki, M. 1994. Age and paleoenvironments of Tertiary in Plotopteridae). Natural History Museum of Los Angeles available. We collected a well-preserved avian rostrum from of KMNH VP 600013. hook, this groove descends towards, but never actually throughout rostral to caudal, and does not provide sufficient grooves and strongly curved tips. Additionally, KMNH VP northwestern Kyushu on the basis of planktonic County, Contributions in Science, 330: 51–57. the Lower Oligocene Yamaga Formation of Ashiya Group in reaches, the crista tomialis. In ventral view, the premaxillae are space for the apertura nasi ossea, suggesting that the apertura 600013 also shows morphological similarity with another foraminifers. Monthly Chikyu, 16: 150–153. Olson, S. L. and Hasegawa, Y. 1979. Fossil counterparts of Ainoshima Island, Kitakyushu City, Japan. This is the first fused along the midline and form a slightly concave palatal nasi ossea are absent or extremely diminished. The extremely protopterid Tonsala hildegardae (SMF Av 599) from the Kato, H. and Karasawa, H. 1994. Minohellenus macrocheilus giant penguins from the North Pacific. Science, 206: record of a complete and extremely well-preserved avian LOCALITY AND GEOLOGICAL SETTING surface. reduced apertura nasi ossea are considered to be one of the Oligocene Pysht Formation of Washington State, U.S.A., in sp. nov. (Decapoda: Crustacea) from the Oligocene 688–689. rostrum from the Paleogene in Kyushu and the purpose of the Remarks. KMNH VP 600013 is characterized by being synapomorphies of Suloidea sensu Cracraft (1985) (Smith, having distinct longitudinal grooves and subsequent very Ashiya Group, Kyushu, Japan. Bulletin of the Kitakyushu Olson, S. L. and Hasegawa, Y. 1996. A new genus and two present paper is to provide a brief description of the newly The new material was retrieved from a sea cliff on the slender and flat, having a strongly curved tip, and a 2010), and therefore KMNH VP 600013 likely belongs to reduced slit-like apertura nasi ossea (Mayr et al., 2015). Museum of Natural History, 13: 51–58. new species of gigantic Plotopteridae from Japan (Aves: collected material. western coast of Ainoshima Island, 10 km north of Kitakyushu sharply-defined longitudinal groove. Most of these features are Suliformes. Osteological and phylogenetic studies have demonstrated the Kawabe, S., Ando, T. and Endo, H. 2014. Enigmatic affinity in Pelecaniformes). Journal of Vertebrate Paleontology, 16: City, Fukuoka Prefecture, Japan (33° 59′ 27″ N, 130° 48′ 58″ E) generally found in Suliformes and Procellariiformes, but the KMNH VP 600013 also resembles a specimen of close affinity between Plotopteridae and Suloidea (Olson and the brain morphology between plotopterids and penguins, 742–751. 38 Soichiro Kawabe, Yusuke Ando, Shigenori Kawano and Kumiko Matsui A rostrum of waterbird from Ainoshima Island, Japan 39

(Fig. 1). The horizon that yielded the specimen consists of fine Hasegawa, 1979, 1996; Olson, 1980; Mayr, 2005; Sakurai et with a comprehensive comparison among water birds. Ozaki, M., Hamasaki, S. and Yoshii, M. 1993. Geology of the Tomita, T. and Oji, T. 2010. Habitat reconstruction of sandstone marked by cross-stratification, including nodules, al., 2008; Smith, 2010; Mayr et al., 2015). On the other hand, Zoological Journal of the Linnean Society, 170: 467–493. Orio district. With Geological Sheet Map at 1:50000. Oligocene elasmobranchs from Yamaga Formation, and has produced abundant remains of marine molluscs and there is much evidence of similarity between Plotopteridae and Knoll, F. and Kawabe, S. 2020. Avian palaeoneurology: Geological Survey of Japan, Tsukuba. Ashiya Group, Western Japan. Paleontological Research, shark teeth (Fig. 2). Stratigraphically, the type horizon belongs Sphenisciformes (Mayr, 2005; Kawabe et al., 2014; Mayr et reflections on the eve of its 200th anniversary. Journal of Sakakura, N. 2002. Taphonomy of the bivalve assemblages in 14: 69–80. to the Yamaga Formation, which in turn forms the lowermost al., 2015), and although the phylogenetic relationship between Anatomy, 236: 965–979. the upper part of the Paleogene Ashiya Group, southwest- Uyeno, T., Yabumoto, Y. and Kuga, N. 1984. Fossil fishes of part of the Ashiya Group (Ozaki et al., 1993; Nakae et al., them is controversial, this study concludes that KMNH VP Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, ern Japan. Paleontological Research, 6: 101–120. Ashiya Group – (1); Late Oligocene elasmobranchs from 1998). The group is widely distributed in the northern area of 600013 is tentatively a member of Suliformes, taking into Tenth Edition, 2 Volumes. L. Salvii, Stockholm. Sakurai, K., Kimura, M. and Katoh, T. 2008. A new penguin- Island of Ainoshima and Kaijima Kitakyushu. Bulletin of Fukuoka Prefecture and consists mostly of shallow marine account the possibility that it belongs to Plotopteridae. Mayr, G. 2005. Tertiary plotopterids (Aves, Plotopteridae) and like bird (Pelecaniformes: Plotopteridae) from the Late the Kitakyushu Museum of Natural History, 5: 135–142. deposits rich in molluscs (e.g., Sakakura, 2002), crabs (e.g., a novel hypothesis on the phylogenetic relationships of Oligocene Tokoro Formation, northeastern Hokkaido, Kato and Karasawa 1994; Ando and Karasawa 2010), shark penguins (Spheniscidae). Journal of Zoological Systematics Japan. Oryctos, 7: 83–94. teeth (e.g., Uyeno et al., 1984; Tomita and Oji, 2010), marine ACKNOWLEDGEMENTS and Evolutionary Research, 43: 61–71. Smith, N. D. 2010. Phylogenetic analysis of Pelecaniformes mammals (Okazaki, 1984, 2012) and birds (e.g., Hasegawa et Mayr, G., Goedert, J. L. and Vogel, O. 2015. Oligocene (Aves) based on osteological data: implications for al., 1979; Okazaki 1989; Olson and Hasegawa, 1996). The age We thank Daisuke Nakatani (Nagasaki City) for helping plotopterid skulls from western North America and their waterbird phylogeny and fossil calibration studies. PLoS of the Yamaga Formation is the latest Early Oligocene with our fieldwork. We also thank Yoshikazu Hasegawa bearing on the phylogenetic affinities of these ONE, 5: e13354. DOI: 10.1371/journal.pone.0013354 (CP19a), based on calcareous nannofossil and planktonic (Gunma Museum of Natural History) and Hiroaki Karasawa penguin-like seabirds. Journal of Vertebrate Paleontology, foraminiferal evidence (Okada and Bukry, 1980; Okada, 1992; (Mizunami Fossil Museum) for useful discussions, and Karin 35: e943764. DOI: 10.1080/02724634.2014.943764 Ibaraki, 1994). Iwasa (Naniwa-Honehone-Dan) for providing images of extant Nakae, S., Ozaki, M., Ota, M., Yabumoto, Y., Matsuura, H. Institutional Abbreviations — KMNH: Kitakyushu Museum phalacrocoracids. This manuscript was greatly improved by and Tomita, S. 1998. Geology of the Kokura district. With of Natural History and Human History, Kitakyushu, Japan. comments from Nathan D. Smith (Natural History Museum of Geological Sheet Map at 1:50000. Geological Survey of Los Angeles County), and an anonymous reviewer. Japan, Tsukuba. Okada, H. 1992. Calcareous nannofossils and biostratigraphy SYSTEMATIC PALAEONTOLOGY of the Paleogene sequences of northern Kyushu, Japan. REFERENCES Journal of the Geological Society of Japan, 98: 505–528. Class Aves Linnaeus, 1758 Okada, H. and Bukry, D. 1980. Supplementary modification Order Suliformes sensu Chesser et al., 2010 Ando, Y. and Karasawa, H. 2010. Mud shrimp associated with and introduction of code numbers to the low-latitude INTRODUCTION burrows from the Oligocene Ashiya Group, northern Coccolith biostratigraphic Zonation (Bukry, 1973; 1975). Material. KMNH VP 600013, almost complete Kyushu, Japan, with description of a new species of Marine Micropaleontology, 5: 321–325. The Oligocene Ashiya Group is rich in marine inverte- premaxillae (Fig. 3). Upogebia (Decapoda: Gebiidea). Zootaxa, 2337: 63–68. Okazaki, Y. 1984. An occurrence of fossil sirenia (Mammalia) brate and vertebrate fossils (e.g., Hasegawa et al., 1979; Uyeno Locality and Horizon. The western coast of Ainoshima Chesser, R. T., Banks, R. C., Barker, F. K., Cicero, C., Dunn, from the Ashiya Group, Kyushu, Japan. Bulletin of the et al., 1984; Okazaki, 1984, 1989, 2012; Kato and Karasawa, Island, Kitakyushu City, Fukuoka Prefecture, Japan; Yamaga J. L., Kratter, A. W., Lovette, I. J., Rasmussen, P. C., Kitakyushu Museum of Natural History, 5: 189–195, pls. 1996; Olson and Hasegawa, 1996; Sakakura, 2002; Ando and Formation, Ashiya Group, Early Oligocene. Remsen, JR. J. V., Rising, J. D., Stotz, D. F. and Winker, 8–9. Karasawa, 2010; Tomita and Oji, 2010). Although many avian Measurements. Length: 88.0 mm; maximum height: 8.3 K. 2010. Fifty-first Supplement to the American Okazaki, Y. 1989. An occurrence of fossil bony-toothed bird fossils have been collected and studied from this group (e.g., mm; maximum width: 12.1 mm. Ornithologists' Union check-list of North American birds. (Odontopterygiformes) from the Ashiya Group (Oligo- Okazaki 1989; Olson and Hasegawa, 1996; Kawabe et al., Description. The rostrum is relatively slender, elongate The Auk, 127: 726–744. cene), Japan. Bulletin of the Kitakyushu Museum of Natu- 2014; Knoll and Kawabe, 2020), no rostrum has been triangular in dorsal view, and flat with little variation in slender rostrum with little variation in dorsoventral depth is indeterminate plotopterid (Suliformes) (KMNH VP 200008) Cracraft, J. 1985. Monophyly and phylogenetic relationships ral History, 9: 123–126. described. Kawabe et al. (2014) and Knoll and Kawabe (2020) dorsoventral depth throughout. The cross-section of the mainly found in cormorants. Furthermore, the strongly curved (Kawabe et al., 2014) discovered from the Ashiya Group of the Pelecaniformes: A numerical cladistic analysis. The Okazaki, Y. 2012. A new mysticete from the upper Oligocene showed a photograph and CG image of the entire skull of rostrum is triangular and gradually becomes smaller from tip is a characteristic of Procellariiformes, Scopus, frigatebirds, (upper Oligocene) in Touno, Kitakyushu City. The rostrum of Auk, 102: 834–853. Ashiya Group, Kyushu, Japan and its significance to indeterminate plotopterid (Suliformes) (KMNH VP 200008) caudal to rostral end. The dorsal and ventral margins of the and cormorants (Smith, 2010), and KMNH VP 600013 is the Touno specimen (KMNH VP 200008) is relatively well Hasegawa, Y., Isotani, S., Nagai, K., Seki, K., Suzuki, T., mysticete evolution. Bulletin of the Kitakyushu Museum of found in the Ashiya Group, but a detailed osteological posterior portion are straight, and the rostral tip is pointed and similar to that of cormorants. However, KMNH VP 600013 preserved, but has been deformed and damaged, and the Otsuka, H., Ota, M. and Ono, K. 1979. Preliminary notes Natural History and Human History, Ser. A (Natural description of this specimen has not been made. Since the strongly curved to form a ventrally directed hook. Laterally, differs from cormorants in having a lateral groove on the preparation has not been completed, so detailed aspects of its on the Oligo-Miocene penguin-like birds from Japan. History), 10: 129–152. rostrum of KMNH VP 200008 was heavily deformed and each premaxilla bears a sharply-defined longitudinal groove, premaxilla that does not reach the crista tomialis. The posterior morphology are unknown. However, the rostrums of KMNH Bulletin of the Kitakyushu Museum of Natural History, 1: Olson, S. L. 1980. A new genus of penguin-like pelecaniform further physical preparation was difficult, the information on flanked on either side by a series of foramina neurovascularia part of KMNH VP 600013 is not fully preserved. However, the VP 600013 and the Touno specimen are morphologically very 41–60. bird from the Oligocene of Washington (Pelecaniformes: the avian rostrum found in the Ashiya Group is hardly and accompanied shallow sulci. Just posterior to the terminal dorsoventral depth of KMNH VP 600013 varies little similar in that they are slender and have strong longitudinal Ibaraki, M. 1994. Age and paleoenvironments of Tertiary in Plotopteridae). Natural History Museum of Los Angeles available. We collected a well-preserved avian rostrum from hook, this groove descends towards, but never actually throughout rostral to caudal, and does not provide sufficient grooves and strongly curved tips. Additionally, KMNH VP northwestern Kyushu on the basis of planktonic County, Contributions in Science, 330: 51–57. the Lower Oligocene Yamaga Formation of Ashiya Group in reaches, the crista tomialis. In ventral view, the premaxillae are space for the apertura nasi ossea, suggesting that the apertura 600013 also shows morphological similarity with another foraminifers. Monthly Chikyu, 16: 150–153. Olson, S. L. and Hasegawa, Y. 1979. Fossil counterparts of Ainoshima Island, Kitakyushu City, Japan. This is the first fused along the midline and form a slightly concave palatal nasi ossea are absent or extremely diminished. The extremely protopterid Tonsala hildegardae (SMF Av 599) from the Kato, H. and Karasawa, H. 1994. Minohellenus macrocheilus giant penguins from the North Pacific. Science, 206: record of a complete and extremely well-preserved avian LOCALITY AND GEOLOGICAL SETTING surface. reduced apertura nasi ossea are considered to be one of the Oligocene Pysht Formation of Washington State, U.S.A., in sp. nov. (Decapoda: Crustacea) from the Oligocene 688–689. rostrum from the Paleogene in Kyushu and the purpose of the Remarks. KMNH VP 600013 is characterized by being synapomorphies of Suloidea sensu Cracraft (1985) (Smith, having distinct longitudinal grooves and subsequent very Ashiya Group, Kyushu, Japan. Bulletin of the Kitakyushu Olson, S. L. and Hasegawa, Y. 1996. A new genus and two present paper is to provide a brief description of the newly The new material was retrieved from a sea cliff on the slender and flat, having a strongly curved tip, and a 2010), and therefore KMNH VP 600013 likely belongs to reduced slit-like apertura nasi ossea (Mayr et al., 2015). Museum of Natural History, 13: 51–58. new species of gigantic Plotopteridae from Japan (Aves: collected material. western coast of Ainoshima Island, 10 km north of Kitakyushu sharply-defined longitudinal groove. Most of these features are Suliformes. Osteological and phylogenetic studies have demonstrated the Kawabe, S., Ando, T. and Endo, H. 2014. Enigmatic affinity in Pelecaniformes). Journal of Vertebrate Paleontology, 16: City, Fukuoka Prefecture, Japan (33° 59′ 27″ N, 130° 48′ 58″ E) generally found in Suliformes and Procellariiformes, but the KMNH VP 600013 also resembles a specimen of close affinity between Plotopteridae and Suloidea (Olson and the brain morphology between plotopterids and penguins, 742–751. 38 Soichiro Kawabe, Yusuke Ando, Shigenori Kawano and Kumiko Matsui A rostrum of waterbird from Ainoshima Island, Japan 39

(Fig. 1). The horizon that yielded the specimen consists of fine Hasegawa, 1979, 1996; Olson, 1980; Mayr, 2005; Sakurai et with a comprehensive comparison among water birds. Ozaki, M., Hamasaki, S. and Yoshii, M. 1993. Geology of the Tomita, T. and Oji, T. 2010. Habitat reconstruction of sandstone marked by cross-stratification, including nodules, al., 2008; Smith, 2010; Mayr et al., 2015). On the other hand, Zoological Journal of the Linnean Society, 170: 467–493. Orio district. With Geological Sheet Map at 1:50000. Oligocene elasmobranchs from Yamaga Formation, and has produced abundant remains of marine molluscs and there is much evidence of similarity between Plotopteridae and Knoll, F. and Kawabe, S. 2020. Avian palaeoneurology: Geological Survey of Japan, Tsukuba. Ashiya Group, Western Japan. Paleontological Research, shark teeth (Fig. 2). Stratigraphically, the type horizon belongs Sphenisciformes (Mayr, 2005; Kawabe et al., 2014; Mayr et reflections on the eve of its 200th anniversary. Journal of Sakakura, N. 2002. Taphonomy of the bivalve assemblages in 14: 69–80. to the Yamaga Formation, which in turn forms the lowermost al., 2015), and although the phylogenetic relationship between Anatomy, 236: 965–979. the upper part of the Paleogene Ashiya Group, southwest- Uyeno, T., Yabumoto, Y. and Kuga, N. 1984. Fossil fishes of part of the Ashiya Group (Ozaki et al., 1993; Nakae et al., them is controversial, this study concludes that KMNH VP Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, ern Japan. Paleontological Research, 6: 101–120. Ashiya Group – (1); Late Oligocene elasmobranchs from 1998). The group is widely distributed in the northern area of 600013 is tentatively a member of Suliformes, taking into Tenth Edition, 2 Volumes. L. Salvii, Stockholm. Sakurai, K., Kimura, M. and Katoh, T. 2008. A new penguin- Island of Ainoshima and Kaijima Kitakyushu. Bulletin of Fukuoka Prefecture and consists mostly of shallow marine account the possibility that it belongs to Plotopteridae. Mayr, G. 2005. Tertiary plotopterids (Aves, Plotopteridae) and like bird (Pelecaniformes: Plotopteridae) from the Late the Kitakyushu Museum of Natural History, 5: 135–142. deposits rich in molluscs (e.g., Sakakura, 2002), crabs (e.g., a novel hypothesis on the phylogenetic relationships of Oligocene Tokoro Formation, northeastern Hokkaido, Kato and Karasawa 1994; Ando and Karasawa 2010), shark penguins (Spheniscidae). Journal of Zoological Systematics Japan. Oryctos, 7: 83–94. teeth (e.g., Uyeno et al., 1984; Tomita and Oji, 2010), marine ACKNOWLEDGEMENTS and Evolutionary Research, 43: 61–71. Smith, N. D. 2010. Phylogenetic analysis of Pelecaniformes mammals (Okazaki, 1984, 2012) and birds (e.g., Hasegawa et Mayr, G., Goedert, J. L. and Vogel, O. 2015. Oligocene (Aves) based on osteological data: implications for al., 1979; Okazaki 1989; Olson and Hasegawa, 1996). The age We thank Daisuke Nakatani (Nagasaki City) for helping plotopterid skulls from western North America and their waterbird phylogeny and fossil calibration studies. PLoS of the Yamaga Formation is the latest Early Oligocene with our fieldwork. We also thank Yoshikazu Hasegawa bearing on the phylogenetic affinities of these ONE, 5: e13354. DOI: 10.1371/journal.pone.0013354 (CP19a), based on calcareous nannofossil and planktonic (Gunma Museum of Natural History) and Hiroaki Karasawa penguin-like seabirds. Journal of Vertebrate Paleontology, foraminiferal evidence (Okada and Bukry, 1980; Okada, 1992; (Mizunami Fossil Museum) for useful discussions, and Karin 35: e943764. DOI: 10.1080/02724634.2014.943764 Ibaraki, 1994). Iwasa (Naniwa-Honehone-Dan) for providing images of extant Nakae, S., Ozaki, M., Ota, M., Yabumoto, Y., Matsuura, H. Institutional Abbreviations — KMNH: Kitakyushu Museum phalacrocoracids. This manuscript was greatly improved by and Tomita, S. 1998. Geology of the Kokura district. With of Natural History and Human History, Kitakyushu, Japan. comments from Nathan D. Smith (Natural History Museum of Geological Sheet Map at 1:50000. Geological Survey of Los Angeles County), and an anonymous reviewer. Japan, Tsukuba. Okada, H. 1992. Calcareous nannofossils and biostratigraphy SYSTEMATIC PALAEONTOLOGY of the Paleogene sequences of northern Kyushu, Japan. REFERENCES Journal of the Geological Society of Japan, 98: 505–528. Class Aves Linnaeus, 1758 Okada, H. and Bukry, D. 1980. Supplementary modification Order Suliformes sensu Chesser et al., 2010 Ando, Y. and Karasawa, H. 2010. Mud shrimp associated with and introduction of code numbers to the low-latitude INTRODUCTION burrows from the Oligocene Ashiya Group, northern Coccolith biostratigraphic Zonation (Bukry, 1973; 1975). Material. KMNH VP 600013, almost complete Kyushu, Japan, with description of a new species of Marine Micropaleontology, 5: 321–325. The Oligocene Ashiya Group is rich in marine inverte- premaxillae (Fig. 3). Upogebia (Decapoda: Gebiidea). Zootaxa, 2337: 63–68. Okazaki, Y. 1984. An occurrence of fossil sirenia (Mammalia) brate and vertebrate fossils (e.g., Hasegawa et al., 1979; Uyeno Locality and Horizon. The western coast of Ainoshima Chesser, R. T., Banks, R. C., Barker, F. K., Cicero, C., Dunn, from the Ashiya Group, Kyushu, Japan. Bulletin of the et al., 1984; Okazaki, 1984, 1989, 2012; Kato and Karasawa, Island, Kitakyushu City, Fukuoka Prefecture, Japan; Yamaga J. L., Kratter, A. W., Lovette, I. J., Rasmussen, P. C., Kitakyushu Museum of Natural History, 5: 189–195, pls. 1996; Olson and Hasegawa, 1996; Sakakura, 2002; Ando and Formation, Ashiya Group, Early Oligocene. Remsen, JR. J. V., Rising, J. D., Stotz, D. F. and Winker, 8–9. Karasawa, 2010; Tomita and Oji, 2010). Although many avian Measurements. Length: 88.0 mm; maximum height: 8.3 K. 2010. Fifty-first Supplement to the American Okazaki, Y. 1989. An occurrence of fossil bony-toothed bird fossils have been collected and studied from this group (e.g., mm; maximum width: 12.1 mm. Ornithologists' Union check-list of North American birds. (Odontopterygiformes) from the Ashiya Group (Oligo- Okazaki 1989; Olson and Hasegawa, 1996; Kawabe et al., Description. The rostrum is relatively slender, elongate The Auk, 127: 726–744. cene), Japan. Bulletin of the Kitakyushu Museum of Natu- 2014; Knoll and Kawabe, 2020), no rostrum has been triangular in dorsal view, and flat with little variation in slender rostrum with little variation in dorsoventral depth is indeterminate plotopterid (Suliformes) (KMNH VP 200008) Cracraft, J. 1985. Monophyly and phylogenetic relationships ral History, 9: 123–126. described. Kawabe et al. (2014) and Knoll and Kawabe (2020) dorsoventral depth throughout. The cross-section of the mainly found in cormorants. Furthermore, the strongly curved (Kawabe et al., 2014) discovered from the Ashiya Group of the Pelecaniformes: A numerical cladistic analysis. The Okazaki, Y. 2012. A new mysticete from the upper Oligocene showed a photograph and CG image of the entire skull of rostrum is triangular and gradually becomes smaller from tip is a characteristic of Procellariiformes, Scopus, frigatebirds, (upper Oligocene) in Touno, Kitakyushu City. The rostrum of Auk, 102: 834–853. Ashiya Group, Kyushu, Japan and its significance to indeterminate plotopterid (Suliformes) (KMNH VP 200008) caudal to rostral end. The dorsal and ventral margins of the and cormorants (Smith, 2010), and KMNH VP 600013 is the Touno specimen (KMNH VP 200008) is relatively well Hasegawa, Y., Isotani, S., Nagai, K., Seki, K., Suzuki, T., mysticete evolution. Bulletin of the Kitakyushu Museum of found in the Ashiya Group, but a detailed osteological posterior portion are straight, and the rostral tip is pointed and similar to that of cormorants. However, KMNH VP 600013 preserved, but has been deformed and damaged, and the Otsuka, H., Ota, M. and Ono, K. 1979. Preliminary notes Natural History and Human History, Ser. A (Natural description of this specimen has not been made. Since the strongly curved to form a ventrally directed hook. Laterally, differs from cormorants in having a lateral groove on the preparation has not been completed, so detailed aspects of its on the Oligo-Miocene penguin-like birds from Japan. History), 10: 129–152. rostrum of KMNH VP 200008 was heavily deformed and each premaxilla bears a sharply-defined longitudinal groove, premaxilla that does not reach the crista tomialis. The posterior morphology are unknown. However, the rostrums of KMNH Bulletin of the Kitakyushu Museum of Natural History, 1: Olson, S. L. 1980. A new genus of penguin-like pelecaniform further physical preparation was difficult, the information on flanked on either side by a series of foramina neurovascularia part of KMNH VP 600013 is not fully preserved. However, the VP 600013 and the Touno specimen are morphologically very 41–60. bird from the Oligocene of Washington (Pelecaniformes: the avian rostrum found in the Ashiya Group is hardly and accompanied shallow sulci. Just posterior to the terminal dorsoventral depth of KMNH VP 600013 varies little similar in that they are slender and have strong longitudinal Ibaraki, M. 1994. Age and paleoenvironments of Tertiary in Plotopteridae). Natural History Museum of Los Angeles available. We collected a well-preserved avian rostrum from hook, this groove descends towards, but never actually throughout rostral to caudal, and does not provide sufficient grooves and strongly curved tips. Additionally, KMNH VP northwestern Kyushu on the basis of planktonic County, Contributions in Science, 330: 51–57. the Lower Oligocene Yamaga Formation of Ashiya Group in reaches, the crista tomialis. In ventral view, the premaxillae are space for the apertura nasi ossea, suggesting that the apertura 600013 also shows morphological similarity with another foraminifers. Monthly Chikyu, 16: 150–153. Olson, S. L. and Hasegawa, Y. 1979. Fossil counterparts of Ainoshima Island, Kitakyushu City, Japan. This is the first fused along the midline and form a slightly concave palatal nasi ossea are absent or extremely diminished. The extremely protopterid Tonsala hildegardae (SMF Av 599) from the Kato, H. and Karasawa, H. 1994. Minohellenus macrocheilus giant penguins from the North Pacific. Science, 206: record of a complete and extremely well-preserved avian LOCALITY AND GEOLOGICAL SETTING surface. reduced apertura nasi ossea are considered to be one of the Oligocene Pysht Formation of Washington State, U.S.A., in sp. nov. (Decapoda: Crustacea) from the Oligocene 688–689. rostrum from the Paleogene in Kyushu and the purpose of the Remarks. KMNH VP 600013 is characterized by being synapomorphies of Suloidea sensu Cracraft (1985) (Smith, having distinct longitudinal grooves and subsequent very Ashiya Group, Kyushu, Japan. Bulletin of the Kitakyushu Olson, S. L. and Hasegawa, Y. 1996. A new genus and two present paper is to provide a brief description of the newly The new material was retrieved from a sea cliff on the slender and flat, having a strongly curved tip, and a 2010), and therefore KMNH VP 600013 likely belongs to reduced slit-like apertura nasi ossea (Mayr et al., 2015). Museum of Natural History, 13: 51–58. new species of gigantic Plotopteridae from Japan (Aves: collected material. western coast of Ainoshima Island, 10 km north of Kitakyushu sharply-defined longitudinal groove. Most of these features are Suliformes. Osteological and phylogenetic studies have demonstrated the Kawabe, S., Ando, T. and Endo, H. 2014. Enigmatic affinity in Pelecaniformes). Journal of Vertebrate Paleontology, 16: City, Fukuoka Prefecture, Japan (33° 59′ 27″ N, 130° 48′ 58″ E) generally found in Suliformes and Procellariiformes, but the KMNH VP 600013 also resembles a specimen of close affinity between Plotopteridae and Suloidea (Olson and the brain morphology between plotopterids and penguins, 742–751.