Xandarellida is a well-defined clade of Lower Palaeozoic non-biomineralized artiopodans that is exclusively known from the early Cambrian (Stage 3) Chengjiang biota of South China. Here we describe a new member of this group, Xandarella mauretanica sp. nov., from the middle Cambrian (Stage 5) Tatelt Formation of Morocco, making this the first non-trilobite Cambrian euarthropod known from North ...

The emergence of complex patterns of organization close to the Cambrian boundary is known to have happened over a (geologically) short period of time. It involved the rapid diversification of body plans and stands as one of the major transitions in evolution. How it took place is a controversial issue. Here we explore this problem by considering a simple model of pattern formation in multicellu...

The Cambrian radiation represents an interval when nearly 20 animal phyla appear in the fossil record in a short geological time span; however, whether this radiation also represents a period of extremely rapid speciation remains unclear. Here, a stochastic framework is used to test the null hypothesis that diversity changes in one of the dominant Early Cambrian groups, the olenelloid trilobite...

The Staré Město Belt (SMB) in the Central Sudetes forms a Variscan tectonic boundary zone that is located between Saxothuringian and Brunovistulian terranes of Bohemian Massif. three thrust-bounded upper, middle lower lithotectonic units SMB are composed metasedimentary Late Cambrian metavolcanic rocks. A new LA-ICPMS zircon geochronology supported by typology studies mica schists upper unit mi...

Charles Darwin suspected that the Cambrian “explosion” might be an artifact of fossil preservation. A more recent, initially controversial hypothesis that repeated true polar wander (TPW) triggered the Ediacaran-Cambrian explosion of animal life has been supported by numerous paleomagnetic and geochronologic refinements. These data imply 75° of TPW between 535 and 515 million years ago, coincid...

Abstract The Sichuan Basin was a part of the Yangtze Carbonate Platform (YCP) during Cambrian–Ordovician, and marine carbonates were deposited in basin this interval. Although previous studies have evaluated paleogeography, paleoclimate paleoecology basin, they primarily focused on biological evolution basin; however, analysis paleogeography is lacking. This study integrated outcrop sedimentolo...

An important survival strategy for animal species is the so-called niche differentiation between larva and adult. Different developmental stages of the same animal occupy different ecological niches to avoid competing for food or other essential resources. Here, we describe an exceptionally preserved larval stage of the short great appendage (SGA) arthropod (megacheiran) Leanchoilia illecebrosa...

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...

Until now, the fossil record has not been capable of revealing any details of the mechanisms of complex vision at the beginning of metazoan evolution. Here, we describe functional units, at a cellular level, of a compound eye from the base of the Cambrian, more than half a billion years old. Remains of early Cambrian arthropods showed the external lattices of enormous compound eyes, but not the...