Gigantism is widespread among Palaeozoic arthropods, yet causal mechanisms, particularly the role of (abiotic) environmental factors versus (biotic) competition, remain unknown. The eurypterids (Arthropoda: Chelicerata) include the largest arthropods; gigantic predatory pterygotids (Eurypterina) during the Siluro-Devonian and bizarre sweep-feeding hibbertopterids (Stylonurina) from the Carbonif...

The history of the appearance and evolution of the suture, one of the major structural elements of the shells of ammonoids (a subclass of Cephalopoda), is briefly discussed. Its morphology is considered in the Devonian Anarcestida, the first members of which are very similar to the ancestral Bactritoidea, in the Late Devonian Clymeniida, the Devonian–Permian Tornoceratida, the Carboniferous–Per...

Abstract Thirty Devonian-Carboniferous Boundary sections of the Rhenish Slate Mountains and adjacent subsurface areas are reviewed with respect to litho-, event, conodont, ammonoid, sequence, chemostratigraphy. In interval from base uppermost Famennian (Wocklum Beds, Wocklumian) middle Tournaisian (base Lower Alum Shale), 11 conodont 16 ammonoid (sub)zones distinguished. The terminology Hangenb...

The distribution and dispersal histories of Eurypterida are examined in a phylogenetic and palaeogeographic context. It is suggested that all the eurypterid clades originated and had most of their evolutionary history on the palaeocontinents of Laurentia, Baltica, Avalonia, the Rheno–Hercynian Terrane and some presence in Siberia. The Siluro–Devonian Stylonurina and the eurypterine superfamilie...

Recent discoveries of tetrapod trackways in 395 Myr old tidal zone deposits of Poland (Niedźwiedzki et al. 2010 Nature 463, 43-48 (doi:10.1038/nature.08623)) indicate that vertebrates had already ventured out of the water and might already have developed some air-breathing capacity by the Middle Devonian. Air-breathing in lungfishes is not considered to be a shared specialization with tetrapods...

Coelacanths are well-known sarcopterygian (lobe-finned) fishes, which together with lungfishes are the closest extant relatives of land vertebrates (tetrapods). Coelacanths have both living representatives and a rich fossil record, but lack fossils older than the late Middle Devonian (385-390 Myr ago), conflicting with current phylogenies implying coelacanths diverged from other sarcopterygians...

New observations on the axial skeleton of the extant lungfish Neoceratodus forsteri (Dipnoi; Sarcopterygii) indicate that neural and haemal arch elements develop more independently than previously believed. For example, while the cartilaginous neural arches/spines begin development anteriorly, just behind the skull, the distal supraneurals first form separately in the posterior region of the ax...