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Current Issue   2019 Vol.  8 No.  2 Published: 2019-04-20 Biopalaeogeography and palaeoecology Lithofacies palaeogeography and sedimentology Advances in palaeobotany 109 Review of the bennettitalean genus Weltrichia Mihai Emilian Popa The bennettitalean male reproductive structure Weltrichia Braun 1849 emend. Harris 1969 (Family Williamsoniaceae) is discussed from several points of view, including anatomy and morphology, species diversity and validity, phytogeographical and stratigraphical distribution, and reproduction strategy. A very rare fossil, genus Weltrichia includes 25 valid species distributed in both hemispheres during Triassic and Jurassic times. This contribution critically reviews the systematics of the entire genus, together with its stratigraphical and palaeophytogeographical significance. 2019 Vol. 8 (2): 109-129 [Abstract] ( 270 ) [HTML 1KB] PDF (5666 KB)   ( 91 ) 130 The floristic relationship between the upland and lowland Carboniferous wetlands of Variscan Euramerica ? Evidence from some medullosalean pteridosperm fronds Christopher J. Cleal, Borja Cascales-Miñana Alethopteris grandinii represents remains of fronds of a medullosalean pteridosperm (probably a small tree) that rapidly migrated across the lowland wetland habitats of Variscan Euramerica in middle Asturian (late Moscovian) times. This was probably caused by changing drainage patterns within the lowland coal swamps, in response to climate and landscape changes. However, these medullosaleans had first appeared rather earlier, in early Bolsovian (early Moscovian) times, in upland wetland habitats. These upland habitats may have pre-adapted these plants to the changed condition in the lowland coal swamps. 2019 Vol. 8 (2): 130-141 [Abstract] ( 209 ) [HTML 1KB] PDF (2468 KB)   ( 86 ) 142 Fruits of Scirpus (Cyperaceae) from the early Miocene of Weichang, Hebei Province, North China and their palaeoecological and palaeobiogeographical implications Ping Lu, Ya Li, Jian-Wei Zhang, Xiao-Qing Liang, Yue-Zhuo Li, Cheng-Sen Li This paper describes the fossil fruits of Scirpus weichangensis X.Q. Liang, sp. nov. from the early Miocene of Guangyongfa Village, Weichang County, Hebei Province, North China. The fossil fruits are obovate in shape and their lateral sections are plumply trigonous. The cell walls of the surface are straight. The persistent stout bristles have downward-directed barbellae in distal 1/2. The occurrence of the fossil Scirpus indicates that Guangfayong was a wetland in the early Miocene. Based on the fossil data, the genus likely originated in Western Siberia in the Oligocene, spread during the Miocene, and was finally distributed worldwide in the Holocene. 2019 Vol. 8 (2): 142-149 [Abstract] ( 251 ) [HTML 1KB] PDF (3993 KB)   ( 84 ) Lithofacies palaeogeography and sedimentology 150 Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain C. Arenas, M.C. Osácar, L. Auqué, C. Sancho Textural and stable isotopic features of two middle Pleistocene fluvial stromatolite profiles are compared to a recent stromatolite, both formed in the River Piedra system (NE Spain), to test the reliability of climatic, hydrologic and depositional information derived from ancient records. The Pleistocene stromatolites formed in a multi-domed, highly-inclined cascade-barrage. The recent stromatolite also formed in a highly-inclined cascade of the River Piedra, the sedimentary conditions of which were periodically examined between the years 2000 and 2012. The Pleistocene stromatolites are formed of an alternation of 1) thin large-crystal laminae (type A), with elongated crystals up to 1 mm long, and 2) thick small-crystal laminae (type B), consisting of cyanobacterial fan- and bush-shaped bodies. The textural and isotopic comparison with the recent stromatolite shows that each A-B couplet corresponds to one year. The type-A laminae are comparable to the macrocrystalline laminae that occur in the cool-period deposits of the recent stromatolite, and the type-B laminae are comparable to the warm-period deposits of the recent stromatolite. Water temperatures (Tw), calculated from δ18Ocalcite and present measures of δ18Owater, were similar in the Pleistocene and recent specimens, and close to the measured river Tw. Thus, the Pleistocene stromatolites formed not far from isotopic equilibrium, as did the recent stromatolite. The Pleistocene δ18Ocalcite biannual oscillation is wider in amplitude than in the recent stromatolite, which suggests larger differences in Tw through the year in the Pleistocene than at present. The Pleistocene δ13Ccalcite does not show any pattern; and the values are slightly higher than the recent ones. The co-evolution of δ18O and δ13C is parallel in the Pleistocene stromatolites, matching the recent stromatolite behavior. These results and their comparison with other ancient examples prove that textural and isotopic features in ancient stromatolites are useful tools to infer past depositional, climatic and hydrological conditions. Moreover, interpretations from recent fluvial stromatolites can be extrapolated to past environments to help decipher patterns of past processes, in cases where both recent and ancient stromatolites can be compared within one environmental setting. Such comparisons may be used to help interpretations of ancient stromatolites where the modern ones are not available to study. 2019 Vol. 8 (2): 150-169 [Abstract] ( 196 ) [HTML 1KB] PDF (36638 KB)   ( 57 ) 170 Sedimentology of reefal buildups of the Xiannüdong Formation (Cambrian Series 2), SW China Hao Tang, Stephen Kershaw, Xiu-Cheng Tan, Hong Liu, Fei Li, Cheng Shen, Fei-Fan Lu, Xue-Fei Yang The reefs in the Xiannüdong Formation (Cambrian Series 2) are the oldest archaeocyathan-microbial bioconstructions in China, but the details of their microbial structures have not been previously described. However, a new section at Tangjiahe site, northern Sichuan Province, contains very well-preserved microbial fabrics that provide these details, and is described in this study. The Tangjiahe section contains three levels of reefal buildups that were constructed by a consortium of archaeocyaths and calcimicrobes in varying proportions. The lowest (oldest) reefal buildup is a calcimicrobial biostrome, possibly in the form of a wide mound with a low relief (unconfirmed due to outcrop limitation), which was formed by Epiphyton with rare small archaeocyaths, and is sandwiched by flat-pebble conglomerates. The middle reefal buildup is a high-relief calcimicrobial mound, enclosed by oolites, that was built by intergrown Renalcis and Tarthinia. Archaeocyath fossils are uncommon, and were bound into the framework by microbial carbonates. The uppermost (youngest) reefal buildup is a low-relief archaeocyathan mound lacking calcimicrobes but partly having microbially-clotted textures attached on archaeocyaths. Calcimicrobes built or aided archaeocyaths to form the framework of Tangjiahe reefs. The three buildups formed in low-energy lagoons behind ooid shoals, and the environment was nutrient-rich due to terrigenous influx from adjacent lands. Tangjiahe reefs thus resemble most Early Cambrian reefs, in settings consistent with eutrophic, calm environments, and are characterized by the domination or aid of calcimicrobial components in framework construction. 2019 Vol. 8 (2): 170-180 [Abstract] ( 161 ) [HTML 1KB] PDF (17134 KB)   ( 76 ) 181 Application of channel-belt scaling relationship to Middle Jurassic source-to-sink system in the Saishiteng area of the northern Qaidam Basin, NW China Bing-Qiang Liu, Long-Yi Shao, Xue-Tian Wang, Ya-Nan Li, Jie Xu Palaeodrainage basin, as an important component of the source-to-sink system, contains critical information on provenance and palaeoenvironment. Previous studies indicate that the scaling relationships of source-to-sink system components generally follow power laws, and channel-belt thickness represents a reliable first-order proxy for the drainage area. In this study, a database of borehole cores and geophysical well logs of the Jurassic coal measures from Saishiteng area in the northern Qaidam Basin was used to reconstruct the palaeogeography, and to identify single-story channel-belts. Three palaeochannels, namely, River A, River B and River C, were identified which were persistent throughout the Dameigou and Shimengou Formations during the Middle Jurassic. The mean channel-belt thicknesses of River A, River B and River C in the Dameigou Formation were 9.8 m, 8.9 m and 7.9 m, respectively, and those in the Shimengou Formation were 7.4 m, 6.2 m and 5.4 m, respectively. We estimate the drainage area of three major rivers by using scaling relationships between drainage area and channel-belt thickness. The drainage areas of River A, River B and River C in the Dameigou Formation were 63.0 × 103 km2, 50.1 × 103 km2 and 37.7 × 103 km2, respectively, and those in the Shimengou Formation were 32.3 × 103 km2, 21.2 × 103 km2 and 15.3 × 103 km2, respectively. The drainage basin lengths of River A, River B and River C in the Dameigou Formation were 300.4 km, 239 km and 180.2 km, respectively, and those in the Shimengou Formation were 154.3 km, 101.3 km and 73.1 km, respectively. For both the Dameigou and Shimengou Formations, River A showed the largest scale, followed by River B and River C succeedingly, which was mainly determined by the stretch direction of provenance in the southern Qilian Mountains. The variations of channel-belt thickness, drainage area and drainage basin length between Dameigou and Shimengou Formations are the response of source-to-sink system to the transformation from extension to compression depression during the Middle Jurassic in the northern Qaidam Basin. 2019 Vol. 8 (2): 181-197 [Abstract] ( 207 ) [HTML 1KB] PDF (11269 KB)   ( 92 ) Biopalaeogeography and palaeoecology 198 The first theropod tracks from the Middle Jurassic of Gansu, Northwest China: New and rare evidence of quadrupedal progression in theropod dinosaurs Da-Qing Li, Li-Da Xing, Martin G. Lockley, Anthony Romilio, Jing-Tao Yang, Long-Feng Li A new Middle Jurassic tracksite dominated by non-avian theropod footprints from the Wangjiashan Formation in Pingchuan District, Baojishan Basin, Gansu Province has yielded a unique trackway with four consecutive manus-pes sets. Only three previous examples, all Early Jurassic in age, of theropod trackways are known with convincing examples of manus tracks and in each case, only two tracks were recorded in association with pes tracks with metatarsal impressions and pelvic traces indicating crouching behavior. Thus, this is the first example of manus tracks registered while a theropod trackmaker was walking. This unique configuration is here designated as Grallator pingchuanensis ichnosp. nov. which shows the trackmaker forelimbs registering in a wide straddle gait, much wider than the pes trackway width. G. pingchuanensis confirms previous reports that theropods could occasionally register tridactyl, ectaxonic manus traces. In the case of the Pingchuan trackway, the short step indicates an animal moving at a slow speed, probably due to a soft substrate. 2019 Vol. 8 (2): 198-208 [Abstract] ( 154 ) [HTML 1KB] PDF (10151 KB)   ( 42 )

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