Journal of Palaeogeography
 
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2019 Vol.  8 No.  1
Published: 2019-01-20
Biopalaeogeography and palaeoecology
Lithofacies palaeogeography and sedimentology
Biopalaeogeography and palaeoecology
1 Ornamental feathers in Cretaceous Burmese amber: resolving the enigma of rachis-dominated feather structure
Lida Xing, Pierre Cockx, Ryan C. McKellar, Jingmai O’Connor
Over the last 20 years, compression fossils of feathers surrounding dinosaurs have greatly expanded our understanding of the origin and evolution of feathers. One of the most peculiar feather morphotypes discovered to date are rachis dominated feathers (RDFs), which have also been referred to as proximally ribbon-like pennaceous feathers (PRPFs). These elongate feathers are only found in the tail plumage, typically occurring in pairs with both streamer (not proximally ribbon-like) and racket-plume morphologies recognized. Here we describe a large sample set of isolated and paired RDFs from the Upper Cretaceous Burmese amber (~99 Ma). Amber preserves the finest details of these fragile structures in three dimensions, demonstrating that RDFs form a distinct feather morphotype with a ventrally open rachis, and with significant variability in flexibility, pigmentation, microstructure, and symmetry.
2019 Vol. 8 (1): 1-18 [Abstract] ( 225 ) [HTML 1KB] PDF (1649 KB)   ( 86 )
43 Past climate and vegetation in Southeast Bulgaria —— a study based on the late Miocene pollen record from the Tundzha Basin
Dimiter Ivanov, Maria Lazarova
The results of palynological studies on the late Miocene freshwater deposits of the Tundzha Basin (Southeast Bulgaria, SE Europe) are presented. The basin is relatively well known in terms of geology and palaeogeography. The age of sediments in the Tundzha Basin ranges between the late Miocene to the Pliocene, based on mammal and diatom fossils. We carried out a palynological analysis of clayey sediments interlayered with coal beds from four cores and from one outcrop, aiming to obtain information about the composition and the structure of fossil vegetation. The ratios between the main floristic elements and the composition of the fossil flora are analysed and discussed from a palaeoecological point of view. Several main vegetation palaeocommunities were recorded: swamp forests, mixed mesophytic, communities of aquatic plants, and herbaceous palaeocoenoses. The changes in vegetation and in plant diversity are identified. The palaeoclimate analysis indicates a warm temperature climate with high rainfall and mild winter temperatures, without seasonal drier conditions. The early Pontian climate was about 3-4°C warmer than today, with rainfalls per year at least 300 mm higher than today. The results of palaeoecological analysis of the flora and of the quantitative palaeoclimate data show that the climate in the Southeast Bulgaria indicates a climate change towards slight cooling and some drying. This event is consistent with the period of accumulation of the upper, undivided part of the Elhovo Formation.
2019 Vol. 8 (1): 43-67 [Abstract] ( 198 ) [HTML 1KB] PDF (10179 KB)   ( 45 )
99 The first occurrence of Phlebopteris dunkeri and P. woodwardii (Matoniaceae) from the Middle Jurassic of Iran
Mohammad Taghi Badihagh, Dieter Uhl
The coal horizons of the Middle Jurassic Hojedk Formation of East-Central Iran are fossiliferous, bearing numerous well-preserved fossil plants, comparable to the Shemshak Group/Formation in the Alborz Mountains in Northern Iran. Here we present two recently discovered fossil taxa from the Middle Jurassic Hojedk Formation of the Tabas Block (Central Iran). Based on their distinct morphologies, impression/compression specimens can be assigned to Phlebopteris dunkeri (Schenk) Schenk 1875 and P. woodwardii Leckenby 1864, belonging to Matoniaceae. This is the first record of these two taxa in Iran. Taxa belonging to Equisetaceae, Marattiaceae, Dipteridaceae, Schizaeaceae, Dicksoniaceae, Caytoniales, Bennettitales, Cycadales and Podozamitaceae were observed as accompanying taxa in the studied section. Ecology comparison of the Hojedk Formation plant fossils with the extant relatives of the fossil plant taxa occurring in these deposits indicates accumulation of the host strata under a moist warm (tropical to subtropical) climate during the Middle Jurassic.
2019 Vol. 8 (1): 99-108 [Abstract] ( 170 ) [HTML 1KB] PDF (4731 KB)   ( 41 )
Lithofacies palaeogeography and sedimentology
19 Recurrent hardgrounds and their significance for intra-basinal correlations: a case study of upper Bathonian rocks from the western margin of the Indian Craton
Dhirendra K. Pandey, Franz T. Fürsich, Matthias Alberti, Jitendra K. Sharma, Narendra Swami
A set of two to three prominent hardgrounds can be traced for more than 40 km from east to west within the Jurassic succession of the Jaisalmer Basin at the western margin of the Indian Craton. The hardgrounds started to form under subtidal conditions in a mixed carbonate-siliciclastic setting during the last phase of a transgressive systems tract, i.e. the maximum flooding zone. The age difference between the hardgrounds is very small, but they differ lithologically. Typically, the stratigraphically oldest hardground occurs at the top of a 1-m-thick calcareous sandstone. It is characterized by a spectacular megaripple surface encrusted with oysters and subsequently occasionally bored by bivalves. The hardground is overlain by 10-25 cm of biowackestone to biopackstone, at the top of which another hardground is developed. This second hardground is characterized by abundant bivalve (Gastrochaenolites isp.) and “worm” borings (Trypanites and Meandropolydora isp.) and occasional oyster encrustations. The third hardground can be found within the overlying 60-cm-thick, bioturbated, fossiliferous silty marly packstone. It shows common to abundant oyster encrustations and occasional borings together with reworked concretions. The individual hardground can be well recognized throughout the basin based on lithology and biotic components. The second hardground (biowackestone to biopackstone) with abundant bivalve and worm borings is most prominent and widespread. Lithostratigraphically, these three hardground surfaces belong to the uppermost part of the Bada Bag Member of the Jaisalmer Formation. Based on ammonites, such as Perisphinctes congener (Waagen), brachiopods, and corals, this interval of the Bada Bag Member has been assigned a late Bathonian age. The entire succession above the first hardground is bioturbated up to the overlying marly silt of the Kuldhar Member of the Jaisalmer Formation, which is already Callovian in age. The characteristic hardground lithologies, together with the ammonite record, allow long-distance correlations within the basin emphasizing their importance as valuable marker horizons. The biotic components associated with the hardgrounds and alternating sediments represent high diversity community relicts developed in shallow-water, open-marine environments.
2019 Vol. 8 (1): 19-30 [Abstract] ( 223 ) [HTML 1KB] PDF (9913 KB)   ( 46 )
31 Using geophysical logs to identify Milankovitch cycles and to calculate net primary productivity (NPP) of the Late Permian coals, western Guizhou, China
Zhi-Ming Yan, Long-Yi Shao, David Large, Hao Wang, Baruch Spiro

Milankovitch periodicities of 123 kyr (eccentricity), 35.6 kyr (obliquity), and 21.2 kyr (precession) were identified in geophysical logs of three Late Permian coals: 17#, 18#, and 17+18#, from the Songhe mining area in western Guizhou Province. Based on the astronomic temporal framework, the periods of deposition of the 17# (5.6 m), 18# (6.4 m), and 17+18# (5.4 m) coals were constrained to 140.8-119.8 kyr, 160-136.2 kyr, and 135-114.9 kyr, respectively. The overall depositional period of the 18# coal of 160-136.2 kyr was further subdivided using the wavelet analysis method, into short and precise periods corresponding to the Milankovitch periodicities. It includes one eccentricity periodicity (123 kyr), three obliquity periodicities (35.6 kyr), and five precession periodicities (21.2 kyr). Different thicknesses of the subdivided coal sections, equivalent to the same time span of deposition, indicate different rates of coal deposition, i.e., thicker sections imply higher rates while the thinner sections represent lower rates. The combination of the measured average carbon concentration with the density of the coals gave rise to long-term average values of carbon accumulation rates for the Late Permian coals, in the range of 42.4-50.6 g•C•m-2•a-1. This range corresponds to the long-term average carbon accumulation rates for the initial peat in the range of 60.6-72.3 g•C•m-2•a-1. Based on the known quantitative relation between net primary productivity (NPP) values and long-term average carbon accumulation rates for the Holocene tropical peatlands, the range of NPP values for the Late Permian tropical peatlands was estimated as 242.4-433.8 g•C•m-2•a-1.A comparison of existing information about peatland NPP levels of various ages and latitudes indicated that when conditions of high rain and high humidity prevail in the palaeo-peatland at given latitude, the NPP rates will vary with changes in atmospheric concentration of CO2 and O2. This relationship may lead to the use of coals as an indicator for the concentration of these gases (CO2 and O2) in the contemporaneous atmosphere encompassing the long records of coal deposition.
2019 Vol. 8 (1): 31-42 [Abstract] ( 210 ) [HTML 1KB] PDF (2405 KB)   ( 54 )
Advances in Palaeobotany
68 The complexity of climate reconstructions using the Coexistence Approach on Qinghai-Tibetan Plateau
Zhi-Yong Zhang, Dong-Mei Cheng, Cheng-Sen Li, Wan Hu, Xuan-Huai Zhan, Hong-Li Ji
Quantifying the palaeoclimates of Qinghai-Tibetan Plateau is vital for understanding the uplift history of plateau and the evolution of Asian monsoon since Cenozoic. Recently, the Coexistence Approach (CA) has been employed to reconstruct the palaeoelevation and palaeoclimate of the plateau by several studies. However, the application of CA in mountainous areas and the realism of climate reconstructions via this method are seldom discussed, although the complexity of reconstructions is speculated. Here we reevaluated the realism of climate reconstruction using the CA with modern pollen samples from the Qinghai-Tibetan Plateau, and try to explore the possible factors influencing the precipitation and temperature reconstructions by CA. We suggest that the long-distance transport pollen as a result of the Asian summer monsoon potentially significantly affects the reconstructions both for precipitation and temperature. The precipitation complexly interacting with snowmelt and permafrost thaw leads to the discrepancy between the reconstructed precipitation and the real value. The response temperature for blossoming of dwarfed plants on the plateau is mostly likely higher than the air temperature (usually measured at 1.5 m above ground) due to energy flux or morphological adaptation of inflorescences during the growing season, causing the distortion of temperature reconstructions. Precipitation reconstruction is notoriously difficult as the establishers of CA have already suggested, but reconstructing the low temperatures may be even more challenging on Qinghai-Tibetan Plateau. Though all of the explorations in current paper are in a qualitative way, it offers an inspiration of how appropriately interpret the disagreements between CA results and the observations, and of how to obtain a reasonable reconstruction of palaeoclimate of the plateau.
2019 Vol. 8 (1): 68-77 [Abstract] ( 200 ) [HTML 1KB] PDF (2750 KB)   ( 38 )
Advances in palaeobotany
78 The Jurassic fossil wood diversity from western Liaoning, NE China
Zi-Kun Jiang, Yong-Dong Wang, Ning Tian, Ao-Wei Xie, Wu Zhang, Li-Qin Li, Min Huang
Western Liaoning is a unique region in China that bears diverse types of Jurassic plants, including leaves, fern rhizomes, and wood, providing significant proxy for vegetation and palaeoenvironment reconstruction of the well-known Yanliao Flora in East Asia. In particular, the silicified wood is very abundant in the fossil Lagerstätte of the Jurassic Tiaojishan Formation in Beipiao, western Liaoning. Previous and recent systematic investigations documented a high diversity of the Jurassic wood assemblages. These assemblages are dominated by conifers, followed by cycads and ginkgoaleans. In total, about 30 species belonging to 21 genera of fossil wood have been recorded so far, which are represented by Cycadopsida, Ginkgopsida, Coniferopsida, and Gymnospermae incertae sedis. The evolutionary implications of several distinctive fossil wood taxa as well as palaeoclimate implications are summarized based on their anatomical structures and growth ring patterns. This work approaches the vegetation development and evolutionary significances of the wood taxa and their relatives, and provides clues for the further understanding of the diversity of the Jurassic Yanliao Flora in East Asia.
2019 Vol. 8 (1): 78-88 [Abstract] ( 153 ) [HTML 1KB] PDF (4157 KB)   ( 42 )
89 A new Bergeria (Flemingitaceae) from the Mississippian of Xinjiang, NW China and its evolutionary implications
Ru Feng, Ashalata D’Rozario, Jian-Wei Zhang
A new Bergeria (Lepidodendrales, Flemingitaceae), B. wenquanensis sp. nov., is described in this paper, typically characterized by the longest and elongated leaf cushions ever found. The specimen, collected from the Mississippian of Wenquan County, Xinjiang Uygur Autonomous Region, China, is represented by a fossil stem about two meters long, with distinct leaf cushions. The genus Bergeria has usually been assigned to partially decorticated Lepidodendron stems. Although Cathaysian Lepidodendron have been extensively reported in China, most of them were found in the central, eastern and southern parts of the country, rarely in northwestern China. This new species is so far the westernmost record and the most isolated representative from the Cathaysian Lepidodendron center. Based on the distribution of the Cathaysian Lepidodendron during the Mississippian, most of the species were in the South China Plate near the Equator, while the new species is discrete in the north, far from the Equator. According to the spatiotemporal distribution of Cathaysian Lepidodendron, this genus appeared during the Mississippian, a period which was represented by rather few species, it flourished and expanded northwards during the Pennsylvanian, taking the north block of the South China Plate as the center. Since the Cisuralian to the Guadalupian, the genus became gradually sparser in all areas of distribution, probably due to strong climate change. During the Lopingian, the genus migrated southwards to the South China block and had a broader distribution range again, and it became extinct to the end of this interval. The new species is also significant for the evolution of Lepidodendron leaf cushions. During the Mississippian, the primitive species of Lepidodendron usually had narrow, fusiform leaf cushions, while the Pennsylvanian or Permian species were more variable in shape of leaf cushions, from inverted water-drop, rhomboidal, hexagonal, trapeziform to horizontal rhomboidal.
2019 Vol. 8 (1): 89-98 [Abstract] ( 174 ) [HTML 1KB] PDF (2910 KB)   ( 39 )
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