The Middle Cambrian Oesia disjuncta, a monospecific genus, is known only from the celebrated Burgess Shale of British Columbia. It has been re−interpreted by Szaniawski (Acta Palaeontologica Polonica 50:1–8; 2005) as a chaetognath, a distinctive phylum whose exact position in the protostomes is still controversial. Unequivocal chaetognaths, that have no similarity to Oesia, are already known to...

Sparse material of an agnostid trilobite, previously referred to as Tomagnostus cf. corrugatus (Illing 1916), is recognized as a new species, T. brantevikensis n. sp. It occurs in the middle Cambrian (≈ Cambrian provisional Series 3) Triplagnostus gibbus and Acidusus atavus zones (Almbackenian regional Stage) in Scania, southernmost Sweden, but is very rare. The new species resembles T. corruga...

Ten phosphatized specimens of a small (<180 micrometers) animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, dating from 40 to 55 million years before the Cambrian. Seen in sections, this animal (Vernanimalcula guizhouena gen. et sp. nov.) had paired coeloms extending the length of the gut; paired external pits that could be sense organs; bilate...

A large data base consisting of 40,679 well locations and 196,687 lithologic records was created from Illinois, Indiana, and Wisconsin well construction records for wells drilled during the period 1980-1997. The purpose of the database is to provide information for mapping the surface, thickness, transmissivity and hydraulic conductivity of the Quaternary, Silurian/Devonian, and Cambrian/Ordovi...

The generic name Nordia (N. lepida Rozova, 1968, by original designation) was proposed by Rozova (1968: 108) for a new trilobite genus from the Upper Cambrian of the Tajmyr peninsula (NW Siberia, Krasnojarsk territory, Russian Federation). However, this name was preoccupied by Nordia Jairajpuri and Siddiqi (1964: 2) which is served as a type for a family Nordiidae Jairajpuri & Siddiqi and subfa...

We generalize the brick polytope of V. Pilaud and F. Santos to spherical subword complexes for finite Coxeter groups. This construction provides polytopal realizations for a certain class of subword complexes containing all cluster complexes of finite types. For the latter, the brick polytopes turn out to coincide with the known realizations of generalized associahedra, thus opening new perspec...

The sudden appearance of fossils that marks the so-called 'Cambrian explosion' has intrigued and exercised biologists since Darwin's time. In On the Origin of Species, Darwin made it clear that he believed that ancestral forms 'lived long before' their first fossil representatives. While he considered such an invisible record necessary to explain the level of complexity already seen in the foss...

Late Cambrian to early Ordovician trilobites, the family Olenidae, were tolerant of oxygen-poor, sulfur-rich sea floor conditions, and a case is made that they were chemoautotrophic symbionts. Olenids were uniquely adapted to this habitat in the Lower Paleozoic, which was widespread in the Late Cambrian over Scandinavia. This life habit explains distinctive aspects of olenid morphology: wide th...

• Cavity-dwelling filamentous microorganisms accommodated in a valve-like organism from the uppermost Dengying Formation (Ediacaran) eastern Yunnan are reported for first time. Well-preserved filaments develop mycelial networks with abundant branching pattern. Probable saprophytic interaction between and is discovered. The Ediacaran–Cambrian transition, one of major turning points Earth’s histo...