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Enigmatic macrofossils of late Ediacaran age (580-541 million years ago) provide the oldest known record of diverse complex organisms on Earth, lying between the microbially dominated ecosystems of the Proterozoic [...]

The organization of the head provides critical data for resolving the phylogenetic relationships and evolutionary history of extinct and extant euarthropods (1,2). The early Cambrian-period fuxianhuiids are regarded as basal [...]

SUMMARY The Early--Middle Cambrian Mount Cap Formation, NWT, hosts a diverse range of exceptionally preserved fossils. Like the celebrated Burgess Shale of British Columbia, the Mount Cap contains carbonaceous compression [...]

Ediacaran rangeomorphs were the first substantially macroscopic organisms to appear in the fossil record, but their underlying biology remains problematic. Although demonstrably heterotrophic, their current interpretation as osmotrophic consumers of dissolved organic carbon (DOC) is incompatible with the inertial (high Re) and advective (high Pe) fluid dynamics accompanying macroscopic length scales. The key to resolving rangeomorph feeding and physiology lies in their underlying construction. Taphonomic analysis of three-dimensionally preserved Charnia from the White Sea identifies the presence of large, originally water-filled compartments that served both as a hydrostatic exoskeleton and semi-isolated digestion chambers capable of processing recalcitrant substrates, most likely in conjunction with a resident microbiome. At the same time, the hydrodynamically exposed outer surface of macroscopic rangeomorphs would have dramatically enhanced both gas exchange and food delivery. A bag-like epithelium filled with transiently circulated seawater offers an exceptionally efficient means of constructing a simple, DOC-consuming, multicellular heterotroph. Such a body plan is broadly comparable to that of anthozoan cnidarians, minus such derived features as muscle, tentacles and a centralized mouth. Along with other early bag-like fossils, rangeomorphs can be reliably identified as total-group eumetazoans, potentially colonial stem-group cnidarians. [ABSTRACT FROM AUTHOR]

Most Cambrian arthropods employed simple feeding mechanisms requiring only low degrees of appendage differentiation (1-3). In contrast, post-Cambrian crustaceans exhibit a wide diversity of feeding specializations and possess avast ecological [...]

The analysis of the fossil structures of the Cambrian Burgess Shale have revealed pronounced anatomical and histological discrepancies with molluscan analogues, such that they are interpreted as primitive features of the superphylum Lophotrochozoa. Odontogriphus and Wlwaxia have conceivably represented the early stages of two separate phyla, despite their close relationship.

The deep‐sea hexactinellid sponge Euplectella is an iconic living genus with no known fossil record. The family Euplectellidae (which includes a subset of genera that share the common name 'Venus' flower basket') has a very sparse record from the Middle Cretaceous onwards, and an estimated crown‐group origin at around 300 Ma based on molecular clocks. New material of Venus' flower baskets from the latest Ordovician Anji Biota of China (444 Ma) dramatically extends the known and predicted range of the group, with implications for the diversification of the class Hexactinellida and the timing of development of deep‐sea ecosystems. The new material is described as Anjiplectella davidipharus gen. et sp. nov., with an additional taxon remaining in open nomenclature but demonstrating diversification within the group by this time. [ABSTRACT FROM AUTHOR]

A shallow-water shale unit from the early Neoproterozoic Wynniatt Formation, arctic Canada, preserves an unusually high diversity of organic-walled fossils, including abundant cyanobacteria, several multicellular protists and/or problematica, and more than 30 distinct acritarch species. Recognition of 13 new acritarchs, based on novel ornamentation, excystment structures, and/or wall structure, substantially increases their known diversity for this interval and points to a severe undersampling of the Proterozoic fossil record. Three of these new acritarchs exhibit features characteristic of dinoflagellate cysts and are reasonable candidates for early representatives of the clade, particularly in light of recent molecular phylogenetic analyses and biomarker data. The high diversity of acritarchs in the Wynniatt Formation also bolsters the potential for biostratigraphic resolution in the Neoproterozoic.