Volumes & issues:
21, 2(2017); http://dx.doi.org/10.2517/2016PR009View Description Hide DescriptionAbstract.
Eight specimens of Sphenodus have been collected from the Upper Cretaceous, Coniacian of Nakagawa Town in Hokkaido, northern Japan. They are referred to as S. cf. lundgreni and Sphenodus spp. 1 and 2, and described in detail. Nearly complete specimens of Sphenodus were previously unknown from the Cretaceous in the Pacific region, and the Nakagawa specimens are the first to exhibit distinct root morphologies, which allow comparison at the species level. A review of the occurrences of this genus reveals that their distribution concentrates in the mid- to high palaeolatitude regions. This distributional pattern of Sphenodus may represent its preference for colder water and possibly explains the extinction of this genus across the Paleocene—Eocene boundary, when the thermal maximum began.
A New Genus of the Corythoecidae (Paleozoic Radiolaria) from the Changhsingian (Uppermost Permian) Dalong Formation in Southern Guizhou, South China21, 2(2017); http://dx.doi.org/10.2517/2016PR005View Description Hide DescriptionAbstract.
A new genus of the Corythoecidae (Albaillellaria, Radiolaria) was recovered from the Changhsingian (uppermost Permian) Dalong Formation in Guizhou Province, South China. Qiania Ito and Feng, gen. nov., containing Q. foremanae Ito and Feng, gen. et sp. nov. and Q. uncinata (Rudenko and Panasenko), is characterized by a conical shell consisting of an apical portion and an inflated region with a lateral foramen on the ventral side. The Corythoecidae were thought to range from the Late Devonian to Guadalupian (middle Permian). Therefore, this new find suggests the presence of this family until the latest Permian. Compilation of previous occurrences of corythoecids, in addition to those of Qiania, showed that most corythoecids including Qiania occurred in phosphate-rich facies, and that Qiania occurred in deeper facies than other corythoecids.
Taxonomy and Stratigraphic Changes of Diatom Resting Spores from DSDP Leg 41, Offshore Northwest African Margin, Based on Nannofossil Biostratigraphy21, 2(2017); http://dx.doi.org/10.2517/2016PR019View Description Hide DescriptionAbstract.
We reinvestigated the standard calcareous nannofossil and diatom biostratigraphy zonations from Deep Sea Drilling Project (DSDP) Leg 41 Holes 366 and 369A in the eastern equatorial Atlantic Ocean in order to determine the geologic ages for the low-latitude diatom zonation. Applying the ages of nannofossil zonations to diatom ones, the ages of several diatom bioevents (first occurrence, FO) which determine the biozones of DSDP Holes 366 and 369A are evaluated as follows; FOs of Baxteriopsis brunii (ca. 38.1 Ma), Coscinodiscus excavatus (ca. 33.6 Ma), Cestodiscus reticulatus (ca. 32.9 Ma), Rocella vigilans (ca. 29.8 Ma), Rossiella symmetrica (ca. 29.5 Ma) and Bogorovia veniamini (ca. 28.3 Ma). These ages may be applicable not only for these holes but also for biostratigraphic studies of other holes which contain Paleogene diatoms. Moreover, this paper describes the taxonomy and stratigraphic ranges of marine diatom Chaetoceros resting spores from DSDP Holes 366 and 369A, including two new morpho-species (Vallodiscus truncatuhis Suto sp. nov. and Xanthioisthmus fortii Suto sp. nov.) and its allied species with synonymy lists, light microscopic observations and several key references for each taxon. As the results of counting of each diatom taxon, it was clear that the sedimentation rate and Chaetoceros resting spore abundances and diversities changed abruptly in the earliest Oligocene (ca. 32 Ma). During the separation of the South American and African continents from the Late Cretaceous to earliest Oligocene, a passage arose that acted for the transfer of Antarctic Bottom Water and modulated the bottom current velocities. The southward bottom water and the passage influenced the sedimentation rate and upwelling of nutrient-rich deeper waters stimulated marine productivity and ecology of Chaetoceros across the late Eocene to early Oligocene.
Tainoceratid and Liroceratid Nautilids from the Upper Mississippian Imo Formation of Arkansas, Midcontinent North America21, 2(2017); http://dx.doi.org/10.2517/2016PR020View Description Hide DescriptionAbstract.
As the third installment of our study to describe the cephalopod fauna of the Upper Mississippian Imo Formation, four species of late Chesterian (= Serpukhovian; late early Carboniferous) nautilids are recorded from the dark gray shale of the formation in northwest Arkansas, Midcontinent North America. They include a tainoceratid, Tylonautilus gratiosus (Girty), and three liroceratids, Bistrialites bicostatus (Gordon), Condraoceras? sp. and Peripetoceras kummeli sp. nov. Diagnostic features of P. kummeli separating it from comparable species are its depressed reniform whorl sections with relatively high width/height ratios, large convergent angle of the flanks, and subcentral to subdorsal siphuncular position.
Conodont Biostratigraphy of the Gongwusu Formation (Upper Ordovician) in the Wuhai Area of Inner Mongolia, North China21, 2(2017); http://dx.doi.org/10.2517/2016PR021View Description Hide DescriptionAbstract.
A well preserved Late Ordovician conodont fauna of 18 species has been recovered from seven limestone samples of the Gongwusu section in the Wuhai area of Inner Mongolia, North China. This conodont fauna is composed of Ansella sp., Belodina monitorensis, Coelocerodontus trigonius, Complexodus sp., Dapsilodus viruensis, Drepanoistodus sp., Gen. et sp. indet, Oslodus semisymmetricus, Panderodus gracilis, Periodon cf. aculeatus, Protopanderodus cf. cooperi, P. varicostatus, Protopanderodus sp., Pseudooneotodus mitratus, Scabbardella altipes, Venoistodus cf. balticus, Yaoxianognathus sp. A, and Yaoxianognathus sp., and shows a mixture of North Atlantic, North China and North American Midcontinent affinities. The presence of Belodina monitorensis, Periodon cf. aculeatus, Protopanderodus varicostatus, Scabbardella altipes and Yaoxianognathus sp. A in the fauna indicates an early Sandbian (late Sa1) age. The fauna is dominated by Periodon cf. aculeatus, Scabbardella altipes and Panderodus gracilis and these together with the occurrence of Protopanderodus species, Drepanoistodus sp. and Ansella sp. characterize the Periodon Biofacies, typical of a deeper water (upper slope) setting. Because of its slope habitat, the Gongwusu fauna differs from the contemporaneous faunas reported from the interior North China Platform, but shows a similarity to the coeval faunas in Baltoscandia, South China and Argentina.
Taxonomic Invalidity of Busk's Elephant (Elephas maximus buski Matsumoto, 1927) demonstrated by AMS 14C dating21, 2(2017); http://dx.doi.org/10.2517/2016PR024View Description Hide DescriptionAbstract.
The ages of the holotype and a referred molar of Elephas maximus buski described by Matsumoto in 1927, and a molar supposedly of the same subspecies described by Makiyama in 1938 from Higashi Betsuin temple in Nagoya, were investigated by AMS (Accelerator Mass Spectrometry) dating. The holotype (IGPS 7266) may date from any of four periods between 1676 and 1941 cal AD, with 1732–1777 cal AD being the most probable (40.7% likelihood). The referred specimen (IGPS 5845) most likely dates from 1784–1796 cal AD (39.4% probability), and the specimen from Higashi Betsuin from 1454–1494 cal AD (52.9% probability). The present specimens, including the holotype are, therefore, not fossils. Historical records show that Asian elephants did not inhabit Japan at these times. These molars must have been imported into Japan in some fashion during historical times and do not represent a subspecies distinct from extant Asian elephants, E. maximus. Although the nominal subspecies E. maximus buski is clearly invalid, it is not clear which of the three extant subspecies of Asian elephant is its senior synonym in this research.
Taxonomy of Maastrichtian–Thanetian Deep-Sea Ostracodes from U1407, IODP Exp 342, off Newfoundland, Northwestern Atlantic, part 2: Families Eucytheridae, Krithidae, Thaerocytheridae, Trachyleberididae, and Xestoleberididae21, 2(2017); http://dx.doi.org/10.2517/2016PR011View Description Hide DescriptionAbstract.
Little is known about the taxonomy of Paleocene ostracodes from ocean drilling sites. Herein, we report 14 ostracode species of the families Eucytheridae, Krithidae, Thaerocytheridae, Trachyleberididae, and Xestoleberididae from Cretaceous-Paleocene sediments at U1407 of Integrated Ocean Drilling Program Expedition 342 off Newfoundland, Northwestern Atlantic. We describe five trachyleberidid species new to science: Croninocythereis clavae sp. nov., Phacorhabdotus flabellicarinus sp. nov., Poseidonamicus norrisi sp. nov., Ryugucivis blumi sp. nov., and Trachyleberidea cronini sp. nov.
21, 1(2017); http://dx.doi.org/10.2517/2016PR015View Description Hide DescriptionAbstract.
Echinoid bite traces on Late Cretaceous (early Maastrichtian) bourgueticrinids and isocrinids of southern Poland (Miechów Trough) were documented. The bitten sea lilies co-occurred with Goniopygus, a regular echinoid possessing an Aristotle's lantern. This is the first record of Goniopygus in the lower Maastrichtian of Poland. Considering former studies, as well as direct in situ observations of extant sea lilies and sea urchin behavior, the traces at hand could be most likely linked with predatory actions of the Goniopygus echinoid. Such studies on predatory phenomena are crucial and could provide baseline data concerning the evolutionary trends among organisms engaged in the “arms race”.
Marine Palynomorphs Dominated by Heterotrophic Organism Remains in the Tropical Coastal Shallow-Water Sediment; the Case of Selangor Coast and the Estuary of the Manjung River in Malaysia21, 1(2017); http://dx.doi.org/10.2517/2016PR006View Description Hide DescriptionAbstract.
We aimed to clarify and quantify the abundance of palynomorphs of tropical coastal marine shallow-water sediments collected from Oman, Malaysia, Okinawa and also the Sanriku region of Japan for making a comparison with temperate areas. Palynomorphs in these samples contained phototrophic and heterotrophic dinoflagellate cysts, acritarchs, resting cells of Prasinophyceae and Chrysophyceae, tintinnomorphs, microforaminiferal linings, testate amoebae and resting eggs and body fragments of copepods. The sediment samples from Malaysia, Oman, and Okinawa were characterized by dominance of heterotrophic marine palynomorphs, in particular microforaminiferal linings and heterotrophic dinoflagellate cysts, while the samples from Sanriku were different and dominated by phototrophic and heterotrophic dinoflagellate cysts. In addition subtropical-tropical assemblages were characterized by low cell/grain concentrations, especially phototrophic dinoflagellate cysts. These characteristics of marine palynomorphs in tropical shallow-water sediments may reflect lower production of phytoplankton in water column as well as high sedimentation rates. Also, high densities of heterotrophic palynomorphs consisting of microforaminiferal linings, tintinnomorphs, crustacean remains and other elements are other characteristics for tropical coastal shallow-water marine sediments. It is difficult to explain the abundant occurrences of heterotrophic dinoflagellate cysts based on the grazing food web against the fact of low phytoplankton production.
How Striations of Ophiuroid and Asteroid Trace Fossils were Produced—Observations of Tube-Feet Movement in Living Ophiuroids and Asteroids21, 1(2017); http://dx.doi.org/10.2517/2016PR003View Description Hide DescriptionAbstract.
To clarify the process of producing the striations in the trace fossil Asteriacites, we observed the behavior of living ophiuroids and asteroids in aquariums. When ophiuroids stopped crawling, they buried themselves shallowly in the substratum, removing substratum under their arms and discs by using their tube-feet. The basal-arm tube-feet produce well spaced, fine, parallel striations that are perpendicular to the arm axis. The oral tube-feet produce fine, radial striations in the central depression. When the ophiuroids resumed crawling, they raised their disc and four arms above the substratum and dragged one arm backward. The one backward arm erased the striations, and parallel fine striations remained in four arm depressions. Similarly, asteroids also produced wide and shallow striations perpendicular to the arm axis by tube-feet movement. When the asteroids started to move again, they bulldozed the substratum under the one preceding arm, where the striations were erased. Since the asteroids crawled raising the other four arms by their tube feet which produced rough and deep striations, the wide and shallow striations remained only in a half of each arm depression. The striations of Asteriacites lumbricalis and A. quinquefolius were similar in shape to the striations produced by movement of tube feet of living ophiuroids and asteroids, respectively.