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首页> 外文学位 >Palynomorphs and selected mesofossils from the Cretaceous Dakota Formation, Minnesota, USA.
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Palynomorphs and selected mesofossils from the Cretaceous Dakota Formation, Minnesota, USA.

机译：来自美国明尼苏达州白垩纪达科他组的层状岩体和部分中化石。

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摘要

The middle Cenomanian palynomorphs and selected mesofossils from the Dakota Formation of south central Minnesota were investigated. A total of 218 palynomorphs were recovered. Terrestrial palynomorphs include 41 types of angiosperm pollen in which five types are described as new species, 42 types of gymnosperm pollen, and 78 types of spores of ferns and fern allies. Spores of ferns and fern allies are most diverse among the terrestrial palynomorphs. Other palynomorphs include two types of megaspores, ten types of algal spores and colonies, seven types of fungal spores and fruiting body, 18 types of dinoflagellate cysts, and 20 types of acritarchs. Based upon the occurrence of Artiopollis indivisus, Balmeisporites glenelgensis, Cicatricosisporites crassiterminatus, Dictyophyllidites impensus, and Nyssapollenites sp., the age of the Cretaceous sediments exposed in south central Minnesota is probably middle Cenomanian. Based upon the analysis of angiosperm pollen morphological characters, the pollen types that appear to be insect-pollinated accounted for 77% on average, and the pollen types which appear to be wind-pollinated accounted for 23% on average during the middle Cenomanian. The characteristic vegetation elements of the coastal swamps during middle Cenomanian were diverse angiosperms, dominant ferns and fern allies, and a relative low abundance of gymnosperms. The Trochodendrales and Buxales of the eudicots, which were not recovered from leaf fossil records, probably were present during the middle Cenomanian based upon the angiosperm pollen records. Two new marattioid ferns, Goolangia minnesotensis Hu, Dilcher, H. Schneid. et Jarzen gen. et sp. nov. and Mesozoisynangia trilobus Hu, Dilcher, H. Schneid. et Jarzen gen. et sp. nov., are described based on charcoalified isolated sporangia and synangia. These fossils provide evidence for the existence of marattioid ferns during the mid-Cretaceous in North America and give the first unequivocal documentation of the Marattiaceae in post Jurassic times. Spores of Goolangia minnesotensis are comparable with the dispersed spore Dictyophyllidites impensus, which was distributed from Arizona to Alberta in west central North America during the middle Cenomanian.
机译：研究了明尼苏达州南部中部的达科他组中的中西诺曼期泥岩和部分中化石。总共回收了218个古怪物。陆地上的苔藓植物包括41种被子植物花粉，其中5种被描述为新物种，42种裸子植物花粉，以及78种蕨类植物和蕨类植物同胞孢子。蕨类植物和蕨类植物同伴的孢子在陆地上的孢粉形态中最为多样。其他的拟孢子虫包括两种类型的大孢子，十种藻类孢子和菌落，七种类型的真菌孢子和子实体，十八种双鞭毛囊肿和二十种尖锐湿疣。根据印度小动脉藻，淡水巴尔米孢子，Cassitricosisporites crassiterminatus，小叶锦梭藻和Nyssapollenites sp。的出现，明尼苏达州中南部暴露的白垩纪沉积物的年龄可能是中新生代。通过对被子植物花粉形态学特征的分析，在中切诺曼期中，似乎是昆虫授粉的花粉类型平均占77％，看起来是风授粉的花粉类型平均占23％。中西诺曼尼亚时期沿海沼泽的特征性植被元素是各种被子植物，优势蕨类和蕨类同伴以及裸子植物的相对较低的丰度。根据被子植物花粉的记录，可能没有在叶片化石记录中发现过，而从叶化石记录中发现的Trochodendrales和Buxales可能存在。两个新的马拉蒂蕨类植物，Goolangia minnesotensis Hu，Dilcher，H。Schneid。 et Jarzen gen。等。十一月和中生三叶虫Hu，Dilcher，H. Schneid。 et Jarzen gen。等。 nov。，描述了基于炭化的分离的孢子囊和交感神经。这些化石提供了北美白垩纪中期马拉蒂蕨类植物存在的证据，并为侏罗纪后的第一次关于马拉蒂科的明确记载提供了证据。明尼苏达州的Goolangia的孢子可与分散的孢子Dictyophyllidites Impensus的孢子相媲美，后者在中西诺曼时期从亚利桑那州分布到北美中西部的艾伯塔省。

著录项

  • 作者

    Hu, Shusheng.;

  • 作者单位

    University of Florida.;

  • 授予单位 University of Florida.;
  • 学科 Geology.; Paleontology.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 230 p.
  • 总页数 230
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;古生物学;
  • 关键词

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