The Cambrian fossil record of euarthropods (extant arachnids, myriapods, crustaceans, hexapods) has played a major role in understanding the origins of these successful animals and indicates that early ancestors underwent an evolutionary transition from soft-bodied taxa (lobopodians) to more familiar sclerotized forms with jointed appendages [1-3]. Recent advances in paleoneurology and developm...

The certain fossil record of animals begins around 540 million years ago, close to the base of the Cambrian Period. A series of extraordinary discoveries starting over 100 years ago with Walcott's discovery of the Burgess Shale has accelerated in the last thirty years or so with the description of exceptionally-preserved Cambrian fossils from around the world. Such deposits of "Burgess Shale Ty...

Small shelly fossils (SSFs) are a group of mostly problematic, small skeletal elements preserved primarily through secondary phosphatization. They dominate lower Cambrian diversity, but appear to suffer a sharp decline in the Botomian Stage or equivalent levels outside Siberia. This observed decline coincides with a significant reduction in phosphogenesis, suggesting that it may be attributable...

The possibility of inertial interchange true polar wander (IITPW) events, in which the rotation pole moves 90° with respect to the solid Earth in a matter of ~10 Myr, has been discussed in the geophysical literature for more than three decades. Recent evidence for an IITPW event in Early Cambrian time has renewed interest in the issue; however, the veracity of supporting palaeomagnetic evidence...

A reservoir model of a Recent steady-state sedimentary system in which the reduced sulfur and oxidized sulfur reservoirs were coupled with the oxidized carbon and reduced carbon reservoirs was constructed. The time curve of the sulfur isotope ratios of the sedimentary sulfate reservoir was used to drive the model back to the beginning of Cambrian time (600 million years ago), producing the rese...

The classic Chengjiang Lagerstätte (Lower Cambrian, Atdabanian stage: Yu'anshan Formation) Yunnan, southwestern China, has yielded, besides the exceptional and often controversial soft-bodied fossils, a fauna of primitive/early lingulid brachiopods. Diandongia pista (Rong 1974) is one of the commonest and most strongly mineralized of the phosphatic brachiopods from the Lagerstätte. The shells o...

During the latest Neoproterozoic to Mid-Cambrian time (580–505 Ma ago), the Earth underwent significant changes in palaeogeography that included rifting of a possible supercontinent and the near simultaneous formation of a second, slightly smaller supercontinent. It is against this tectonic backdrop that the Cambrian radiation occurred. Although the general tectonic setting during this interval...

Bioturbation plays a substantial role in sediment oxygen concentration, chemical cycling, regeneration of nutrients, microbial activity, and the rate of organic matter decomposition in modern oceans. In addition, bioturbators are ecosystem engineers which promote the presence of some organisms, while precluding others. However, the impact of bioturbation in deep time remains controversial and l...

It is often presumed, that life evolves relatively fast on planets with clement conditions, at least in its basic forms, and that extended periods of habitability are subsequently needed for the evolution of higher life forms. Many planets are however expected to be only transiently habitable. On a large set of otherwise suitable planets life will therefore just not have the time to develop on ...

The assembly of the Gondwana supercontinent during the waning stages of the Proterozoic provides a tectonic backdrop for the myriad biological, climatological, tectonic and geochemical changes leading up to, and including, the Cambrian radiation. A polyphase assembly of Gondwana during the East Africa, Brasiliano, Kuungan and Damaran orogenies resulted in an extensive mountain chain which deliv...