Ordovician trilobites are reviewed based on a new species-level relational database. The stratigraphical ranges of all 56 families with occurrences in the Ordovician are documented and the content, phylogenetic status, diversity and Ordovician distribution by major palaeocontinent/terrane are discussed. Aspects of higher classification are also dealt with. Global sampling is heavily biased towa...

Moulting behaviors in trilobites are a crucial strategy during development. Previous studies have demonstrated inter-and intraspecific variability of moulting behavior trilobites. Currently, ecdysial motifs for considered not stable even within species and fewer detailed dealt with single trilobite Here large sample meraspid to holaspid exuviae Arthricocephalites xinzhaiheensis (131 specimens) ...

Beecher's Trilobite Bed in the Frankfort Shale of New York State preserves an exceptional record of the benthic macrofauna of a Late Ordovician deepwater marine environment. It has long been famous for specimens of the trilobites Triarthrus eatoni (Hall), Cryptolithus bellulus (Ulrich), Primaspis crosotus (Locke), and Cornuproetus beecheri (Ruedemann), new combination, which preserve the ventra...

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...

Morphological variation within species is a raw material subject to natural selection. However, temporal change in morphological diversity has usually been studied in terms of variation among rather than within species. The distribution of polymorphic traits in cladistic character-taxon matrices reveals that the frequency and extent of morphological variation in 982 trilobite species are greate...

cambrian sediments are widely exposed in the kerman province. parts of these deposits are containing trilobite fossils. one of the suitable areas for paleontological studies is kamar siah section. this section located about 60 km north east of kerman. these sediments have 200 m thickness with fossil invertebrates of trilobites, brachiopod, gastropods and stromatolite which includes kuhbanan and...

The Cambrian 'Orsten' fauna comprises exceptionally preserved and phosphatised microscopic arthropods. The external morphology of these fossils is well known, but their internal soft-tissue anatomy has remained virtually unknown. Here, we report the first non-biomineralised tissues from a juvenile polymerid trilobite, represented by digestive structures, glands, and connective strands harboured...