Paleontological Research
Volume 11, Issue 1, 2007
Volumes & issues:
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ARTICLES
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Ocadia nipponica, a new species of aquatic turtle (Testudines: Testudinoidea: Geoemydidae) from the Middle Pleistocene of Chiba Prefecture, central Japan
View Description Hide DescriptionABSTRACTA new species of the genus Ocadia (Testudines; Testudinoidea; Geoemydidae), O. nipponica, is described on the basis of a nearly complete skeleton from the Middle Pleistocene Kiyokawa Formation of the Shimosa Group at Sodegaura City, Chiba Prefecture, central Japan. O. nipponica is distinguished from O. sinensis (Gray) by its more extensive secondary palate, smoother shell surface, narrower second and third vertebral scutes, and larger size (carapace up to 33 cm long). Considering that the living species O. sinensis is distributed in the coastal area of eastern to southeastern Asia in subtropical to tropical climates, the new fossil species may have been thrived in warmer paleoclimatic conditions for the Japanese Islands in the Pleistocene age than hitherto have been estimated on the basis of floral evidences.
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The youngest record of trace fossil Rosselia socialis: Occurrence in the Holocene shallow marine deposits of Japan
View Description Hide DescriptionABSTRACTThe trace fossil Rosselia socialis Dahmer, 1937 is a thickly mud-lined and spindle-shaped tube oriented vertically or obliquely to the bedding plane. It is known to record detailed information on the pa-leoenvironment. Although it has been reported from Lower Cambrian to upper Pleistocene deposits, no Holocene specimens have previously been found. Well preserved specimens of R. socialis are herein reported from the Holocene shallow marine deposits at Shima, Tako Town, Chiba Prefecture, central Japan, co-occurring with some prehistoric earthenware vessels that were made from 9950 to 2950 yrs. B.P. This is the youngest record of R. socialis.
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Occurrence of Epilucina californica (Conrad) (Bivalvia: Lucinidae) from the Neogene of Japan, with notes on the biogeographic history of Epilucina
View Description Hide DescriptionABSTRACTThe California lucine, Epilucina californica (Conrad, 1837), is reported from lower Middle Miocene to Upper Pliocene strata in Japan. This extends the oldest record of this species and represents the first detailed record of the species and genus in the western North Pacific region. Based on the Paleogene fossil record of Epilucina and the general migration pattern of Neogene North Pacific mollusks, it is inferred that E. californica originated in the eastern North Pacific during Late Oligocene or Early Miocene time and migrated westward to the western North Pacific during the early Middle Miocene. The western North Pacific populations of E. californica became extinct by the end of the Pliocene, whereas the eastern North Pacific populations survive in California. This species is, therefore, regarded as a northeastern Pacific restriction taxon. Two Japanese fossil species, Lucina (Myrtea) nipponica Nomura and Hatai, 1936 and Lucina japonica Ozaki, 1958 are junior synonyms of E. californica.
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Occurrence of dinoflagellate cyst genera Wanaea and Komewuia in Upper Jurassic strata, coastal Tanzania
View Description Hide DescriptionABSTRACTSpecies of the dinoflagellate cyst genera Komewuia and Wanaea are well represented in surface and subsurface, Upper Jurassic strata of coastal Tanzania. One new species of Wanaea, W. tendaguruensis, is described from the Trigonia smeei Bed of the Tendaguru Formation in the Mandawa Basin; it appears to be a useful index of the Kimmeridgian. Wanaea clathrata, W. spectabilis, and W. talea are rare to common constituents of the Oxfordian strata of the middle part of the Bagamoyo Formation in the Ruvu Basin. Komewuia glabra, characteristic of the Kimmeridgian-Tithonian in the southern hemisphere, is recorded from the offshore Kipatimu Formation and from the Trigonia smeei Bed. The Kipatimu Formation was previously dated as Early Cretaceous, but is now considered Late Jurassic due to its content of K. glabra. The informally designated Komewuia sp. A occurs sporadically in the Nerinea Bed (Oxfordian-Kimmeridgian) of the Tendaguru Formation. The species documented herein have short stratigraphic ranges in the Upper Jurassic of coastal Tanzania and are thus potentially useful for regional biozonation and correlation.
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New observations on the palaeoscolecid worm Tylotites petiolaris from the Cambrian Chengjiang Lagerstätte, south China
View Description Hide DescriptionABSTRACTThe Lower Cambrian Chengjiang Lagerstätte provides a remarkable window to enable investigation of the early diversification of introvert worms. Tylotites petiolaris Luo and Hu, 1999 is a very rare animal of the fauna originally regarded as a kind of lobopodian based on an incomplete specimen, but its affinities to recent phyla are still controversial. New materials of the taxon collected in recent years confirm that it is most closely related to the palaeoscolecidians with which it shares features such as a proboscis consisting of a slightly swollen introvert bearing many scalids, a collar (buccal cone) and a spinose pharynx. Both possess a smooth neck as a median zone between the introvert and the trunk, a pair of terminal hooks and a trunk bearing transverse ridges intercalated with furrows. Therefore, a new order Cricocosmida of the class Palaeoscolecida is erected herein based on these shared characters. The trunk spines of T. petiolaris are somewhat dorsoventrally differentiated indicating an epifaunal life on the sea floor. Numerous fine transverse wrinkles possibly beneath the uppermost cuticle of the ventral trunk of the animal are tentatively interpreted as the circular muscles, a feature crucial to understanding the problematic systematic position of the palaeoscolecidians.
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New carnivoran material (Creodonta, Carnivora and Incertae sedis) from the Early Miocene of Napak, Uganda
View Description Hide DescriptionABSTRACTEight species of creodonts and carnivores have previously been reported from the Early Miocene deposits at Napak, Uganda. This paper takes into account unpublished material from old collections made by W.W. Bishop during the 1950s and 1960s, as well as new samples made by the Uganda Palaeontology Expedition between 1985 and 2005. Four carnivoran species are reported from the site for the first time, of which one is a new genus and species, and one species is removed from previous lists, making for a grand total of 12 species for Napak comprising 6 creodonts, 4 fissipeds and two incertae sedis.
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Suidae and Hippopotamidae from the Middle Miocene of Kipsaraman, Kenya and other sites in East Africa
View Description Hide DescriptionABSTRACTAfrican Middle Miocene suiform faunas are rather poorly known. Some taxa are well represented at one or two sites, but in general the material is rather scrappy. As a result, there has been confusion about which taxa are present at which localities, and differences of opinion exist about which specimens belong to which taxa. The discovery of a rich and diverse suoid fauna at Kipsaraman, a Middle Miocene site in Kenya, helps to throw light on several lineages including kubanochoeres and kenyapotamines. The fauna also contains remains of namachoerines and listriodonts.
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