Cetricycas antarcticus gen. et sp. nov. occurs in the Late Coniacian to Campanian Lachman Crags Member of the Santa Marta Formation, Marambio Group, James Ross Island, Antarctica. The petrified trunk comprises a thick pith containing thin and thick walled parenchymous cells, vascular traces surrounded by a thin layer of loose secondary wood. Medullary bundles arise inside the wood zone and pass outwards through multiseriate medullary rays. The trunk anatomy indicates assignment to the Cycadales, and the presence of medullary bundles indicates the affinities with a clade comprising Lepidozamia, Macrozamia, and Encephalartos. This clade is presently confined to Australia and Africa, but fossil representatives extend the geographic range to India, South America and now Antarctica. 相似文献
Independence between attributes on artifacts with two equivalent loci has ordinarily been tested only when the loci can be differentiated from each other, say as left or right side or as distal or proximal end. If such an identification does not exist, is uncertain or is irrelevant, then a test of independence requires a special statistical procedure. Such a procedure is given here. Applications are illustrated for coreplatforms, geometric microliths and arrow-head typology, and an extension to artifacts with several equivalent loci is determined. 相似文献
Song, J., Crasquin, S. & Gong, Y., September 2016. Ostracods of the Late Devonian Frasnian/Famennian transition from western Junggar, Xinjiang, NW China. Alcheringa 41, xxx–xxx. ISSN 0311-5518.
Ostracods are described for the first time from the Late Devonian of western Junggar in Xinjiang, NW China. Fifty-two species belonging to 30 genera are recognized, and seven are new: Arcuaria hebukesarensis sp. nov., Bairdia shaerbuertiensis sp. nov., Cribroconcha honggulelengensis sp. nov., Microchelinella bulongourensis sp. nov., M. hoxtolgayensis sp. nov., Pribylites wulankeshunensis sp. nov. and P. junggarensis sp. nov. The ostracod fauna indicates a probable late Frasnian age for the lower member of the Hongguleleng Formation, and the Frasnian/Famennian boundary may exist in the basal part of the formation. The ostracod assemblages are referable to the Eifelian Mega-Assemblage, incorporating both the palaeocopid and smooth-podocopid associations. The fauna implies deposition in a nearshore–offshore environment during a transgression when the lower member of the Hongguleleng Formation was being deposited in western Junggar.
Junjun Song [hnlisa@126.com], State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, PR China; CR2P, MNHN-UPMC- CNRS, Sorbonne Universités, Université Pierre et Marie Curie, T46-56, E.5, case 104, 75252 Paris cedex 05, France; Sylvie Crasquin [sylvie.crasquin@upmc.fr], CR2P, MNHN-UPMC-CNRS, Sorbonne Université, Universités Pierre et Marie Curie, T46-56, E.5, case 104, 75252 Paris cedex 05, France; Yiming Gong* [ymgong@cug.edu.cn], State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, PR China.相似文献
By combining underwater survey with formal and compositional study of ceramics, recent work at Burgaz (south‐west Turkey) reveals a late 6th‐ or 7th‐century assemblage of wine and perhaps other agricultural products carried in LR1 and LR2‐related amphoras. Representing various south‐east Aegean and likely Cilician producers, the mixed cargo aboard this probable shipwreck offers insights into the complex dynamics of seaborne distribution at the end of Antiquity. This brief study also underscores the need for documentation in underwater survey of amphora forms and fabrics, particularly those from a period characterized by intensified and diversified production of supra‐regional ceramic types. 相似文献
This paper summarizes phytolith analyses from four pre-Columbian agricultural raised-field sites of the coastal savannahs of French Guiana—Savane Grand Macoua, Piliwa, Bois Diable and K-VIII—and carbon isotope analyses from the first-named site. The combined phytolith and 13C isotope analyses evidence the transformation of the landscape from a relatively homogeneous wetland vegetation comprised of a mixture of C4 and C3 plants (the latter including Cyperaceae and other herbaceous monocots such as Marantaceae and Heliconia, Oryzoideae grasses, and other plants typical of frequently flooded areas) to the construction of raised fields that were dominated by C4 plants (maize and other Panicoideae grasses). Our analysis proves the utility of phytoliths for tracing the agricultural history of landscapes, showing that, as in other parts of the Central and South American lowlands, maize (Zea mays) was one important crop cultivated in raised fields. We also estimated the productivity of raised-field agriculture, showing that in combination with other subsistence activities, it certainly had the capacity to sustain sizeable populations. 相似文献
Recent investigations at the prehistoric Purrón Dam Complex in the Tehuacán Valley of southern Puebla, México applied radiometric dating to more securely date the complex. Ceramic-based dating in the 1960′s placed the Dam's origin to the Formative Period. While Formative Period origins are widely accepted, the chronology lacks resolution and direct dates. Samples from impounded sediments behind the dam and from prehistoric canal fill were dated through Optically Stimulated Luminescence (OSL) as well as both standard 14C and accelerated mass spectrometry (AMS) assays. These samples directly date the functioning of the water management features within the complex. The results confirm the Formative Period origins of the Purrón Dam, and offer new insights into the construction and functioning of the dam and irrigation system. 相似文献