Contrasts between the Cambrian Explosion (CE) and the Great Ordovician Biodiversification Event (GOBE) have long been recognized. Whereas the vast majority of body plans were established as a result of the CE, taxonomic increases during the GOBE were manifested at lower taxonomic levels. Assessing changes of ichnodiversity and ichnodisparity as a result of these two evolutionary events may shed...

Two characters are stratigraphically compatible if some phylogenies indicate that their combinations (state-pairs) evolved without homoplasy and in an order consistent with the fossil record. Simulations assuming independent character change indicate that we expect approximately 95% of compatible character pairs to also be stratigraphically compatible over a wide range of sampling regimes and g...

The Neoproterozoic glacial intervals represent one of the most curious expressions of Earth’s climate. Despite the popularity of the hard “Snowball” hypothesis in the popular press, the scientific community remains divided over the extent of the Neoproterozoic glaciations, the age of the glaciations, the number of glacial events and the triggering mechanism for the glaciations. A major, and yet...

Several severe glaciations occurred during the Neoproterozoic eon, and especially near its end in the Cryogenian period (630-850 Ma). While the glacial periods themselves were probably related to the continental positions being appropriate for glaciation, the general coldness of the Neoproterozoic and Cryogenian as a whole lacks specific explanation. The Cryogenian was immediately followed by t...

U–Pb ages were obtained on single detrital zircon grains separated from six samples of Neoproterozoic and Lower Palaeozoic sedimentary and volcanosedimentary rocks from NW Iberia using the laser ablation microprobe-inductively coupled plasma mass spectrometry (LAM-ICP-MS) method. Precambrian greywackes yielded abundant zircons with Neoproterozoic (800–640 Ma) and Mesoproterozoic (0.9–1.2 Ga) ag...

5.14.5 References Planetary Moment of Inertia and the Spin-Axis Apparent Polar Wander (APW) = Plate motion + TPW Different Information in Different Reference Frames Type 0' TPW: Mass Redistribution at Clock to Millenial Timescales, of Inconsistent Sense Type I TPW: Slow/Prolonged TPW Type II TPW: Fast/Multiple/Oscillatory TPW: A Distinct Flavor of Inertial Interchange Hypothesized Rapid or Prol...

Aeolian sandstones are found intimately associated with Late Neoproterozoic ‘snowball Earth’ glacial deposits. Studying the nature of these aeolian deposits offers the great potential to elicit new and important information regarding the wind conditions during these extreme glacial intervals. Wind direction is the dominant paleoclimatic indicator that can be derived from aeolian deposits and on...

The Athel silicilyte is an enigmatic, hundreds of meters thick, finely laminated quartz deposit, in which silica precipitated in deep water (>~100-200 m) at the Ediacaran-Cambrian boundary in the South Oman Salt Basin. In contrast, Meso-Neoproterozoic sinks for marine silica were dominantly restricted to peritidal settings. The silicilyte is known to contain sterane biomarkers for demosponges, ...