Vol.22 No.1

View abstract

The family Eschrichtiidae is presently only represented by Eschrichtius robustus, a relict species from the North Pacific. Because of the scarcity of fossil records of the Eschrichtiidae, their evolutionary history is not well understood. A finely preserved mysticete skeleton was recovered from the Lower Pleistocene (1.77–1.95 Ma) of Tokyo, Japan, in 1961. The fossil consists of a cranium, mandibles, cervical, thoracic, lumbar and caudal vertebrae, chevrons, ribs, and forelimb bones, including scapula, humerus, radius, ulna and digit bones. Here, we describe and diagnose this fossil as a new species of the Eschrichtiidae, Eschrichtius akishimaensis sp. nov. This is the first fossil species of the genus Eschrichtius and suggests that at least two lineages represented by the modern species of Eschrichtius and the new species described here survived as late as the Early Pleistocene. This expands our knowledge of the paleodiversity of the eschrichtiids.

View abstract

Nine longiconic cephalopod species of Desmoinesian (Middle Pennsylvanian; upper Carboniferous) pseudorthoceratid orthocerids are described from the Buckhorn Asphalt Lagerstätte (Boggy Formation) in Southcentral Oklahoma, Midcontinent North America. The fauna consists of Pseudorthoceras knoxense (McChesney), Arbuckleoceras tricamerae (Smith), Bitaunioceras buckhornense (Smith), Cyrtothoracoceras? sp., Dolorthoceras boggyense sp. nov., Smithorthoceras unicamera (Smith), Sueroceras oklahomense (Smith), Sulphurnites taffi sp. nov. and Unklesbayoceras striatulum sp. nov. Bitaunioceras buckhornense represents the first Pennsylvanian and therefore the oldest record of this genus. Arbuckleoceras gen. nov. differs from a comparable genus, Shikhanoceras, in possessing a weak exogastric curvature with a circular cross section of the conch and in lacking a conspicuous inflation at the embryonic shell. Smithorthocerasgen. nov. resembles orthoceratids rather than pseudorthoceratids in characters of camerae and siphuncle; however it refers to the Pseudorthoceratidae by having endosiphuncular deposits. These similarities seem to be the result of convergent evolution. Endosiphuncular deposits in Sulphurnites gen. nov. initiate at apical and adoral junctions between septal neck and connection ring, whose characters are unique for pseudorthoceratids. Unklesbayoceras gen. nov. differs from Mitorthoceras in having the endogastric conch, longer camerae and a less eccentric siphuncle. Taxonomic status of these orthoceratids was uncertain in previous biogeochemical and morphological studies. Sediments in the Buckhorn Asphalt Lagerstätte were deposited in a tropical epeiric sea (the Midcontinent Sea). Small, restricted marine basins, like that in this Oklahoma occurrence, probably provided an orthocerid refuge habitat as indicated by the high diversity and provincialism in comparison with other Middle Pennsylvanian (= Moscovian) faunas in other regions of the world.

View abstract

An upper Paleocene radiolarian-bearing succession (ZN1) located in the southern part of the north subzone of the Tethyan Himalaya is composed of siliceous siltstones and claystones. In this paper, 23 species belonging to 13 genera are reported. Three new species, Lychnocanium? pyramis Li and Matsuoka sp. nov., Lychnocanium? stypticum Li and Matsuoka sp. nov., and Pterocyrtidium sinense Li and Matsuoka sp. nov., are described. Radiolarian assemblages from this succession can be compared with the Bekoma campechensis Zone (RP6), indicating a time interval of 61.5–58.23 Ma, i.e., late Paleocene. The radiolarian assemblages from the Yamdrok mélange, the Zheba section, and the Jiazhu section indicate that they are of the same age as those from the Zhinadibu 1 section. The lack of calcareous and coarse-grained terrestrial materials in the ZN1 section proves that the strata of this section were deposited in a relatively deep marine environment below the calcium carbonate compensation depth (CCD) and more distal to the continents during the late Paleocene. Coeval deepwater sediments near Saga were accumulated near the CCD.

View abstract

Kazacharthrans are exclusively fossil crustaceans restricted to the Triassic and possibly Jurassic period and were first described by Tchernyshev in 1940. Kazachartha is supposed to represent the sister group to Notostraca (tadpole shrimps). Little is known about the morphology of most kazacharthrans, and in general only few publications are available. We present here a specimen with kazacharthan-related traits, which we compare to the co-occurring species Notostraca minor (formerly Triops cancriformis minor), a notostracan representative. Both specimens come from the Museum Terra Triassica in Euerdorf, Lower Franconia, southern Germany and were documented using cross-polarized light and autofluorescence settings to achieve well contrasted, high-resolution images. Key morphological features of the kazacharthran-like specimen are the very broad shield without a dorsal midline and spines, a broad and elongated posterior trunk and a square-shaped telson with lateral bulges. Also some details, like different eye structures, mandibular and cervical groove, intestine, and the paired shell glands are visible. Comparison to Notostraca minor revealed differences in these morphological features between the two specimens. We suggest an interpretation of the presented specimen near Kazacharthra due to the described features and discuss the importance of the specimen for branchiopodan phylogeny and biogeography.

View abstract

The Ediacaran genus Globusphyton Wang et al., only including one species G. lineareWang et al., is a eukaryotic macroalga in the Wenghui biota from black shale of the upper Doushantuo Formation (ca. 560–551 Ma) in northeastern Guizhou, South China. It was assigned as one of the significant fossils in the assemblage and biozone divisions in the middle-late Ediacaran Period. Morphologically, Globusphyton is composed of several structural components, displaying that it had tissue differentiation to serve various bio-functions. Its prostrate stolon, a long ribbon bundled by unbranching filaments, crept by holdfasts on the seafloor. Its pompon-like thalli, the circular to oval thallus-tuft composed of many filamentous dichotomies, may have served for photosynthesis. The fusiform ribbon-tubers, the caked and expanded segments of the ribbon, may have served to sustain the growth of the thalli and the possible holdfasts. The zigzag-shaped stolon and pompon-like thalli of Globusphyton, in a relatively low-energy environment, crept on the surface of the muddy sediments and were suspended in the water column, respectively. When water currents occurred occasionally, all or part of its body was probably suspended in the water column to be deformed in capricious patterns.

View abstract

A newly discovered trilobite from the Naidaijin Formation in the Kurosegawa Terrane of southwest Japan is referred to Toxophacops (Atopophacops) fujiwara sp. nov. The trilobite occurs in strata 2 m below a level with detrital zircons that yield an age of 383.9±4.4 Ma that is likely Givetian (late Mid-Devonian). Elsewhere, Early to Mid-Devonian trilobite species of T. (Atopophacops) and T. (Toxophacops) have been recorded from the Nakazato Formation of the South Kitakami Terrane of northeast Japan, and from the Zhusilenghaierhan region of western Inner Mongolia, North China. The new trilobite species extends the geographical range of the phacopid subfamily Echinophacopinae, and supports the affinities of some Devonian Japanese trilobites with those of north China. The occurrence of Toxophacops in the Lower Member of the Naidaijin Formation, combined with other trilobite evidence, confirms a clear biostratigraphical distinction between the Lower Member (upper Lower and Middle Devonian) and Upper Member (Upper Devonian) of the Naidaijin Formation.

View abstract

Taxonomy of extinct fishes is mostly based on the shapes of their bodies, teeth and skeletons and sometimes the coverage of the body. Analysis of modern fishes shows that sometimes even single-scale morphology can also be used as a taxonomic tool. In spite of the fact that variation in scales character in one species can be broad, some specific features distinguish species of the same genus. Analysis of the fossilized scales of fishes found in the Late Triassic deposits of Krasiejów (SW Poland) shows that the microstructure of the external surface of scales can also be considered as a taxonomic tool in the fossil record. Description of the ornamentation pattern of several scales of fishes from the same group shows diversity of the sculpture, which might be assigned to variation in morphology between several genera or species. Among the scales from Krasiejów there occur the oldest known ctenoid scales (sensu stricto) belonging to acanthopterygians.