Cretaceous Diatoms: Morphology, Taxonomy, Biostratigraphy

1995 ◽  
Vol 8 ◽  
pp. 81-106 ◽  
Author(s):  
David M. Harwood ◽  
Vladimir A. Nikolaev
Keyword(s):  
Lower Cretaceous ◽  
Morphological Changes ◽  
Early History ◽  
Background Information ◽  
Morphological Development ◽  
Diatom Assemblages ◽  
History Of

The Cretaceous record of the diatoms presented here outlines our understanding of their early morphological development. Recent documentation of well preserved Lower Cretaceous (Aptian/Albian) diatom assemblages provides a window into the early history of the diatoms and serves as a base for comparing their subsequent morphological changes. A brief review of diatom biology and morphology is provided to introduce this paper and that of Barron and Baldauf (this volume). Additional background information on the diatoms can be found in the works of Schrader and Schuette (1981), Tappan (1980), Bach and Burkhardt (1984), Barron (1985a, 1993), Fenner (1985), Ricard (1987), Bradbury (1988), Round et al. (1990), and Picket-Heaps et al. (1990).

scholarly journals The palate and choanae structure of theSusisuchusanatoceps(Crocodyliformes, Eusuchia): phylogenetic implications

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5372 ◽  
Author(s):  
Karla J. Leite ◽  
Daniel C. Fortier
Keyword(s):  
Lower Cretaceous ◽  
Fossil Record ◽  
Evolutionary History ◽  
Morphological Changes ◽  
Ventral View ◽  
Structural Evolution ◽  
Sister Group ◽  
Phylogenetic Position ◽  
Phylogenetic Implications ◽  
History Of

Crocodyliformes is a group with a broad fossil record, in which several morphological changes have been documented. Among known transformations the most iconic is perhaps the series of changes seen in the structural evolution of the choanae. The change in the position of the choanae was important during the evolutionary history of the Crocodyliformes. This structure is relevant in the phylogenetic position of many crocodyliforms. The new skull ofSusisuchus anatocepsfrom the Crato Formation of the Santana Group (Lower Cretaceous) is described and the preservation in the ventral view allows character encoding not yet observed for the species. The new specimen shows a typical eusuchian palate forSusisuchus anatoceps, in which the choana is fully enclosed by the pterygoid. The Susisuchidae clade has been placed in different phylogenetic positions: as a sister group of Eusuchia, advanced Neosuchia and in Eusuchia. InIsisfordiathere are reports that the choana of this taxon is or is not fully enclosed by the pterygoid. The encoding of the ventral characters ofS.anatocepsplaces Susisuchidae in Eusuchia. However, this position must be further studied, since the matrices showed fragility in the reconstitution of the Neosuchia–Eusuchia transition.

Some early history of replica techniques for electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1076-1077
Author(s):  
Robert M. Fisher
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Optical Microscope ◽  
Early History ◽  
Bulk Materials ◽  
Thin Sections ◽  
Transmission Electron ◽  
Reflected Light ◽  
History Of ◽  
Electron Microscopes

By 1940, a half dozen or so commercial or home-built transmission electron microscopes were in use for studies of the ultrastructure of matter. These operated at 30-60 kV and most pioneering microscopists were preoccupied with their search for electron transparent substrates to support dispersions of particulates or bacteria for TEM examination and did not contemplate studies of bulk materials. Metallurgist H. Mahl and other physical scientists, accustomed to examining etched, deformed or machined specimens by reflected light in the optical microscope, were also highly motivated to capitalize on the superior resolution of the electron microscope. Mahl originated several methods of preparing thin oxide or lacquer impressions of surfaces that were transparent in his 50 kV TEM. The utility of replication was recognized immediately and many variations on the theme, including two-step negative-positive replicas, soon appeared. Intense development of replica techniques slowed after 1955 but important advances still occur. The availability of 100 kV instruments, advent of thin film methods for metals and ceramics and microtoming of thin sections for biological specimens largely eliminated any need to resort to replicas.

The early history of tuberous sclerosis

1979 ◽  
Vol 115 (11) ◽  
pp. 1317-1319 ◽  
Author(s):  
J. E. Morgan
Keyword(s):  
Tuberous Sclerosis ◽  
Early History ◽  
History Of

New Light on the Early History of the Greater Northwest

2015 ◽  
Author(s):  
Alexander Henry ◽  
David Thompson
Keyword(s):  
Early History ◽  
History Of

The Film World’s Cooperative Store: Institutions and Films of the 1930s and 1940s

2018 ◽  
Author(s):  
C. Claire Thomson
Keyword(s):  
World War Ii ◽  
Meat Products ◽  
Public Information ◽  
Early History ◽  
World War ◽  
International Context ◽  
German Occupation ◽  
History Of ◽  
The Uk ◽  
The Impact

This chapter traces the early history of state-sponsored informational filmmaking in Denmark, emphasising its organisation as a ‘cooperative’ of organisations and government agencies. After an account of the establishment and early development of the agency Dansk Kulturfilm in the 1930s, the chapter considers two of its earliest productions, both process films documenting the manufacture of bricks and meat products. The broader context of documentary in Denmark is fleshed out with an account of the production and reception of Poul Henningsen’s seminal film Danmark (1935), and the international context is accounted for with an overview of the development of state-supported filmmaking in the UK, Italy and Germany. Developments in the funding and output of Dansk Kulturfilm up to World War II are outlined, followed by an account of the impact of the German Occupation of Denmark on domestic informational film. The establishment of the Danish Government Film Committee or Ministeriernes Filmudvalg kick-started aprofessionalisation of state-sponsored filmmaking, and two wartime public information films are briefly analysed as examples of its early output. The chapter concludes with an account of the relations between the Danish Resistance and an emerging generation of documentarists.

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