During vertebrate gastrulation, large cellular rearrangements lead to the formation of the three germ layers, ectoderm, mesoderm and endoderm. Zebrafish offer many genetic and experimental advantages for studying vertebrate gastrulation movements. For instance, several mutants, including silberblick, knypek and trilobite, exhibit defects in morphogenesis during gastrulation. The identification ...

Modularity of the cranidium of Crassifimbra? metalaspis, a Cambrian ptychoparioid trilobite, is investigated using landmark-based geometric morphometric methods to gain insight into the integration among morphogenetic processes responsible for shaping the head of an ancient arthropod. Of particular interest is the extent to which the structure of phenotypic integration was governed by direct in...

The Lower and Middle Cambrian age acritarch assemblages are reported from a continuous succession of the siliciclastic-carbonate Ribota, Huermeda Daroca Formations in Iberian Chains, northeastern Spain. One new genus four species described, one them open nomenclature. microfossil allow to recognize Heliosphaeridium dissimilare - Skiagia ciliosa Volkovia dentifera ­Liepaina plana zones, disc...

Many three-dimensionally preserved exoskeletons found from the middle Cambrian (Stage 5) Gaotai Formation in Guizhou, southern China, have been assigned to the ptychopariid trilobite Gunnia sp. They represent mainly a series of early instars, exhibiting some delicate structures and morphological variation associated with their trunk segmentation and early development. Morphometric and statistic...

New fossil discoveries are reported from the Grammajukku Formation at Luobákte south of Lake Torneträsk in northern Swedish Lapland, including a fauna Small Shelly Fossils (SSF) limestone bed uppermost part formation and new occurrences brachiopods trilobites siltstones lower formation. The moderately diverse SSF is first its kind Caledonides includes record tommotiid Lapworthella schodackensis...