Early Cambrian

The basal part of the Hüdai Formation (Early Cambrian) in the Aydıncık (Mersin) area comprises red sandstone beds at different stratigraphic levels, showing ripple cross-lamination. These beds were deposited in the middle to lower part of an intertidal flat environment. Bedding-parallel reddening and its cyclic character suggest syn-sedimentary or early diagenetic red colouration in a marine environment.

11p vidonut2711 09-11-2019 8 1   Download

In previous studies, they were described as Mo Dong or Than Sa Formations (Middle-Upper Cambrian). The graptolite faunas newly discovered from the Dinh Ca Market - Na Mo - Dong Bo cross section are composed of Expansograptus urbanus (Monsen), Expansograptus abnormis (Hsu), Tetragraptus quadribrachiatus (Hall), T. approximatus Nicholson, T. pacificus Ruedemann, T. decipiens T.S. Hall, Schizograptus sp., belonging to the quadribrachiatus Biozone, indicating Floian Stage or late Early Ordovician.

11p meolep1 28-11-2018 26 1   Download

By studying Darwin’s finches and East African cichlids, scientists can get clues that help them understand much older, much bigger adaptive radiations. One of the biggest was the early rise of animals. This period of animal evolution is sometimes nicknamed “the Cambrian explosion.” Unfortunately, that name gives the impression that all the modern groups of animals popped into existence 540 million years ago at the dawn of the Cambrian period. Animals evolved from protozoans, which left fossils over a bil- lion years before the Cambrian.

37p machuavo 19-01-2013 38 3   Download

CHAPTER ELEVEN Evolution of the Hardground Community Hardground communities first appeared in the late Middle Cambrian but they were not common before the Ordovician. Two factors had a major influence on the early development of hardgrounds and resulted in abrupt and rapid increase in hardground area.

16p lqhoang 30-11-2010 72 6   Download

CHAPTER TEN Evolution of Shallow-Water Level-Bottom Communities Features of Cambrian level-bottom communities that inhabited carbonate and siliciclastic substrates are outlined. A high diversity of level-bottom communities with multiple trophic guilds was established in the Early Cambrian.

21p lqhoang 30-11-2010 80 5   Download

CHAPTER NINE Ecology and Evolution of Cambrian Plankton Probable eukaryotic phytoplankton first appear in the fossil record in the Paleoproterozoic but undergo almost no morphologic change until the Early Cambrian. The radiation of diverse acanthomorphic phytoplankton in exact parallel with the Cambrian explosion of large animals.

17p lqhoang 30-11-2010 87 6   Download

CHAPTER EIGHT Biotic Diversity and Structure During the Neoproterozoic-Ordovician Transition Diversity of 4,122 metazoan genera, 31 calcimicrobial genera, and 470 acritarch species are plotted for the Nemakit-Daldynian– early Tremadoc interval at zonal level.

29p lqhoang 30-11-2010 59 7   Download

CHAPTER SIX Australian Early and Middle Cambrian Sequence Biostratigraphy with Implications for Species Diversity and Correlation This description of Lower and Middle Cambrian strata from the Stansbury, Arrowie, Amadeus, and Georgina basins combines elements of biostratigraphy and sequence stratigraphy.

30p lqhoang 30-11-2010 72 7   Download

CHAPTER THREE Global paleogeographic world maps compiled for the late Vendian, Cambrian, and Early to Middle Ordovician bring together, possibly for the first time, a systematic and uniform overview of paleogeographic and facies distribution patterns for this interval.

22p lqhoang 30-11-2010 75 5   Download

CHAPTER TWO Recent revisions to the early Paleozoic time scale have been used to recalibrate ages assigned to stratigraphically dated paleomagnetic poles of that era. In particular, a value of 545 Ma has been used for the base of the Cambrian. Selected poles have then been used to derive apparent polar.

38p lqhoang 30-11-2010 69 7   Download