Phyletic trends in uppermost Triassic (Rhaetian) Radiolaria: Two examples from Queen Charlotte Islands, British Columbia, Canada

Risella Carter and Laxtorum Blome, two genera from the diverse Rhaetian fauna of the Sandilands Formation, Queen Charlotte Islands, are used to illustrate phyletic trends in latest Triassic Radiolaria. Several distinct morphotypes constituting a lineage are recognized for each genus. These lineages are homogenous, evolved in situ, and show a continuum of variation through time. The evolution of Risella takes place entirely in the Rhaetian and all species disappear at the end of the Triassic. Earliest species of Laxtorum appear in the upper Norian and evolve rapidly in the Rhaetian. All Rhaetian species go extinct at the end of the Triassic but the genus survives marginally into the Lower Jurassic. Morphological transformations in Risella (a paronaellid) are manifest in the external/cortical shell as the shape changes from triangular to three-rayed. In Laxtorum, distal post abdominal chambers become constricted and eventually develop a terminal tube while, at the same time, an increase in size and sphericity is coupled with a reduction in the number of post abdominal chambers. Evolutionary transitions in the Risella lineage probably represent a reversion of the normal hypothesized trend for paronaellid radiolarians. In the Laxtorum lineage, comparisons with other groups and species displaying similar homeomorphies suggest the evolutionary trends are fundamental and occur repeatedly in faunas of all ages.

Agreed-upon procedures report on the City of Gilman, Iowa for the period September 1, 2013 through August 31, 2014

Agreed-upon procedures report on the City of Gilman, Iowa for the period September 1, 2013 through August 31, 2014

15/2/20, Thionville, la grande-duchesse Charlotte [de Luxembourg] et M. Poincaré [revue des troupes, le jour de la remise de la croix d'honneur à la ville] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 58022

[Demande de la citoyenne Charlotte Sophie Renneville dite Dufayel d'être rayée de la listes des émigrés]

Datation d'après le contenu du document

Jane Eyre: del text a la pantalla : Un estudi comparatiu entre l'obra de Charlotte Brontë i l'adaptació cinematogràfica de Cary Fukunaga

Treball de fi de màster que estudia comparativament les relacions entre la novel·la "Jane Eyre" de Charlotte Brontë i l'adaptació cinematogràfica de la mateixa realitzada pel director Cary Fukunaga.

Bedford jossa Perkins diesel

kuv., 14 x 27 cm

Saksalaistutkija Charlotte Henze : "Kansalliskirjastossa vietän tutkimuksen juhlaa"

Haastateltavana tutkija Charlotte Henze.