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Articles 1 - 5 of 5
Full-Text Articles in Geology
Exceptionally Preserved Jellyfishes From The Middle Cambrian, Paulyn Cartwright, Susan L. Halgedahl, Jonathan R. Hendricks, Richard D. Jarrard, Antonio C. Marques, Allen G. Collins, Bruce S. Lieberman
Exceptionally Preserved Jellyfishes From The Middle Cambrian, Paulyn Cartwright, Susan L. Halgedahl, Jonathan R. Hendricks, Richard D. Jarrard, Antonio C. Marques, Allen G. Collins, Bruce S. Lieberman
Jonathan R. Hendricks
Cnidarians represent an early diverging animal group and thus insight into their origin and diversification is key to understanding metazoan evolution. Further, cnidarian jellyfish comprise an important component of modern marine planktonic ecosystems. Here we report on exceptionally preserved cnidarian jellyfish fossils from the Middle Cambrian (~505 million years old) Marjum Formation of Utah. These are the first described Cambrian jellyfish fossils to display exquisite preservation of soft part anatomy including detailed features of structures interpreted as trailing tentacles and subumbrellar and exumbrellar surfaces. If the interpretation of these preserved characters is correct, their presence is diagnostic of modern jellyfish …
International, Cooperative Research In The Apuseni Mountains Of Western Romania, Lee J. Florea, Bogdan P. Onac
International, Cooperative Research In The Apuseni Mountains Of Western Romania, Lee J. Florea, Bogdan P. Onac
Lee J Florea, PhD, P.G.
In May of 2006, nine American scientists and cavers from the Karst Research Group at the University of South Florida traveled to western Romania to attend and present at an international conference on records of climate change in caves in the historic Roman town of Baile Hurculane. The conference, co-sponsored by the “Emil Racoviţă” Speleological Institute of Romania and the Karst Waters Institute, drew more than 100 experts in the field of climate change and karst, and was a wonderful time spent alongside the thermal springs and Austro-Hungarian bathhouses nestled within the massive limestone canyon of the Cerna River. Following …
I Sinkholes Nella Letteratura Scientifica Internazionale: Una Breve Rassegna, Con Particulare Riferimento Agli Stati Uniti D'America, Lee J. Florea, Mario Parise
I Sinkholes Nella Letteratura Scientifica Internazionale: Una Breve Rassegna, Con Particulare Riferimento Agli Stati Uniti D'America, Lee J. Florea, Mario Parise
Lee J Florea, PhD, P.G.
Fenomeni di sinkholes sono diffusi in moltissimi paesi del mondo, in ambiti geologici e morfologici alquanto differenziati, e coinvolgono svariate litologie, sia nelle successioni di copertura che in quelle direttamente affioranti alla superficie. Il presente contributo intende fornire una breve rassegna, certamente non esaustiva, sullo stato dell’arte delle ricerche relative ai sinkholes in ambito internazionale. Esso consiste in una descrizione della più aggiornata e diffusa classificazione dei sinkholes e, a seguire, in descrizioni delle più tipiche casistiche di sinkholes nei vari paesi. Tra questi, viene dato particolare risalto agli Stati Uniti d’America (e, più in particolare, alla Florida), dove le …
Fractal Characterization Of Fracture Networks: An Improved Box-Counting Technique, Ankur Roy, Edmund Perfect, William M. Dunne, Larry Mckay
Fractal Characterization Of Fracture Networks: An Improved Box-Counting Technique, Ankur Roy, Edmund Perfect, William M. Dunne, Larry Mckay
Larry McKay
Box counting is widely used for characterizing fracture networks as fractals and estimating their fractal dimensions (D). If this analysis yields a power law distribution given by N $\propto$ r−D, where N is the number of boxes containing one or more fractures and r is the box size, then the network is considered to be fractal. However, researchers are divided in their opinion about which is the best box‐counting algorithm to use, or whether fracture networks are indeed fractals. A synthetic fractal fracture network with a known D value was used to develop a new algorithm for the box‐counting method …
Biogeography And The Cambrian Radiation Of Arachnomorph Arthropods, Jonathan R. Hendricks, Bruce S. Lieberman
Biogeography And The Cambrian Radiation Of Arachnomorph Arthropods, Jonathan R. Hendricks, Bruce S. Lieberman
Jonathan R. Hendricks
Biogeographic patterns in primarily Cambrian arachnomorph taxa are investigated using a recently constructed phylogenetic hypothesis in order to explore the biogeographic context of the Cambrian radiation. A modified version of Brooks Parsimony Analysis is employed to elucidate patterns of vicariance and geodispersal in taxa from six regions (Laurentia, Baltica, Siberia, Australia, Africa and China). Well resolved vicariance and geodispersal trees are very similar and reconstruct Laurentia and China as sister areas. This close area relationship between Laurentia and China provides extensive evidence for congruent vicariance and range expansion in Cambrian arachnomorphs, while data from trilobites do not show this pattern. …