Influence of different substrates on the evolution of morphology and life‐history traits of azooxanthellate solitary corals (Scleractinia: Flabellidae)

Sessile organisms are influenced considerably by their substrate conditions, and their adaptive strategies are key to understanding their morphologic evolution and traits of life history. The family Flabellidae (Cnidaria: Scleractinia) is composed of the representative azooxanthellate solitary corals that live on both soft and hard substrates using various adaptive strategies. We reconstructed the phylogenetic tree and ancestral character states of this family from the mitochondrial 16S and nuclear 28S ribosomal DNA sequences of ten flabellids aiming to infer the evolution of their adaptive strategies. The Javania lineage branched off first and adapted to hard substrates by using a tectura‐reinforced base. The extant free‐living flabellids, including Flabellum and Truncatoflabellum, invaded soft substrates and acquired the flabellate corallum morphology of their common ancestor, followed by a remarkable radiation with the exploitation of adaptive strategies, such as external soft tissue [e.g. Flabellum (Ulocyathus)], thecal edge spine, and transverse division (e.g. Placotrochus and Truncatoflabellum). Subsequently, the free‐living ancestors of two genera (Rhizotrochus and Monomyces) invaded hard substrates independently by exploiting distinct attachment apparatuses such as tube‐like and massive rootlets, respectively. In conclusion, flabellids developed various morphology and life‐history traits according to the differences in substrate conditions during the course of their evolution. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 184–192.     

Global historical biogeography of hadrosaurid dinosaurs

Hadrosaurids were the most derived ornithopods and amongst the most diverse herbivore dinosaurs during the Late Cretaceous of Europe, Asia, and the two Americas. Here, their biogeographical history is reconstructed using dispersal‐vicariance analysis (DIVA). The results showed that Hadrosauridae originated in North America and soon after dispersed to Asia no later than the Late Santonian. The most recent common ancestor of Saurolophidae (= Saurolophinae + Lambeosaurinae) is inferred to have been widespread in North America and Asia. The split between saurolophines and lambeosaurines occurred in response to vicariance no later than the Late Santonian: the former clade originated in North America, whereas the latter did so in Asia. Saurolophine biogeographical history included a minimum of five dispersal events followed by vicariance. Four of these dispersals were inferred to have occurred from North America to Asia during the Campanian and Early Maastrichtian, whereas a fifth event represented a southward dispersal from North to South America no later than the Late Campanian. The historical biogeography of lambeosaurines was characterized by an early evolution in Asia, with a Campanian dispersal to the European archipelago followed by vicariance. Reconstruction of the ancestral areas for the deepest nodes uniting the more derived lambeosaurines clades (‘hypacrosaurs’, ‘corythosaurs’, and ‘parasaurolophs’) is ambiguous. The split between North American and Asian clades of ‘hypacrosaurs’ and ‘parasaurolophs’ occurred in response to vicariance during the Campanian. The evolutionary history of North American ‘hypacrosaurs’ and ‘parasaurolophs’ was characterized by duplication events. The latter also characterized the Late Campanian ‘corythosaurs’, which remained restricted to North America. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 503–525.     

Climate's role in the distribution of the Cretaceous terrestrial Crocodyliformes throughout Gondwana

A high diversity of terrestrial crocodyliform species has been found in the continental Cretaceous deposits of Gondwana. They are widespread in the sedimentary basins of Brazil, Uruguay, Argentina, Bolivia, Morocco, Cameroon, Niger, Malawi, Madagascar and Pakistan, from alluvial, fluvial and lacustrine deposits. A peculiar aspect of these terrestrial crocodyliforms is that only some of them are cosmopolitan. They comprise distinct groups as the basal Notosuchia, baurusuchids, sphagesaurids and Sebecian peirosaurids. There is a distribution pattern of the terrestrial Crocodyliformes faunas throughout the Cretaceous. The oldest are composed of the small and probably omnivorous Notosuchia and Araripesuchus, found in Early Cretaceous deposits. In the Late Cretaceous this fauna was enriched by the medium-sized to large-size baurusuchids, sphagesaurids, peirosaurids and larger Araripesuchus which present specializations as active terrestrial predators. The distribution analysis of the terrestrial Crocodyliformes from Early and Late Cretaceous palaeogeographic and palaeoclimatic maps indicates that temperature was the principal influence on their Gondwanan distribution. Although expressed seasonality, aridity is a limiting factor for the distribution of extant crocodilians. The Cretaceous basal Notosuchia, baurusuchids, sphagesaurids, Araripesuchus, Sebecian peirosaurids, are found in arid climatic belts during Early and Late Cretaceous. To live in a hot and arid climate they have presumably developed ecological strategies that allowed such habits. The aridity or seasonal warm and cyclic dry and wet climate periods plays a role, that have not yet been analyzed, that may explain the domain of bizarre Crocodyliformes in Gondwana during the Cretaceous.     

Rectogerochammina eugubina nov. gen., nov. sp., a new agglutinated foraminifer from the Upper Cretaceous of Gubbio, Italy

We describe the new agglutinated foraminiferal genus and species Rectogerochammina eugubina nov. gen., nov. sp. from the Upper Cretaceous Scaglia Rossa Formation of the Umbria-Marche Basin in Italy. The genus differs from Gerochammina (Neagu, 1990) in the presence of a terminal uniserial part.     

HOW DID LIFE BECOME SO DIVERSE? THE DYNAMICS OF DIVERSIFICATION ACCORDING TO THE FOSSIL RECORD AND MOLECULAR PHYLOGENETICS

Abstract: The long‐term diversification of life probably cannot be modelled as a simple equilibrial process: the time scales are too long, the potential for exploring new ecospace is too large and it is unlikely that ecological controls can act at global scales. The sum of many clade expansions and reductions, each of which happens according to its own dynamic, probably approximates more a damped exponential curve when translated into a global‐scale species diversification curve. Unfortunately, it is not possible to plot such a meaningful global‐scale species diversification curve through time, but curves at higher taxonomic levels have been produced. These curves are subject to the vagaries of the fossil record, but it is unlikely that the sources of error entirely overwhelm the biological signal. Clades radiate when the external and internal conditions are right: a new territory or ecospace becomes available, and the lineage has acquired a number of characters that open up a new diet or mode of life. Modern high levels of diversity in certain speciose clades may depend on such ancient opportunities taken. Dramatic climatic changes through the Quaternary must have driven extinctions and originations, but many species responded simply by moving to more favourable locations. Ecological communities appear to be no more than merely chance associations of species, but there may be real interactions among species. Ironically, high species diversity may lead to more speciation, not, as had been assumed, less: more species create more opportunities and selective pressures for other species to respond to, rather than capping diversity at a fixed equilibrium level. Studies from the scale of modern ecosystems to global long‐term patterns in the fossil record support a model for the exponential diversification of life, and one explanation for a pattern of exponential diversification is that as diversity increases, new forms become ever more refinements of existing forms. In a sense the world becomes increasingly divided into finer niche space. Organisms have a propensity to speciate freely, species richness within ecosystems appears to generate opportunities for more speciation, clades show all kinds of patterns from sluggish speciation rates and constant diversity through time to apparently explosive speciation, and there is no evidence that rapidly speciating clades have reached a limit, nor that they are driving other clades to extinction. A corollary of this view is that current biodiversity must be higher than it has ever been. Limits to infinite growth are clearly local, regional, and global turnover and extinction events, when climate change and physical catastrophes knock out species and whole clades, and push the rising exponential curve down a notch or two.     

THE TYPE SERIES OF 'SINEMYS'WUERHOENSIS, A PROBLEMATIC TURTLE FROM THE LOWER CRETACEOUS OF CHINA, INCLUDES AT LEAST THREE TAXA

Abstract:  We re-examine the type series of ' Sinemys ' wuerhoensis Yeh (at least 20 specimens, including several shells and skulls on three slabs of matrix and one isolated skull) from the Early Cretaceous Tugulu Group of China. Our study shows that the type series of ' S. ' wuerhoensis is actually a chimera made up of at least three distinct taxa. The holotype of this taxon should be assigned to the basal eucryptodire genus Xinjiangchelys Yeh. As there are no characters that distinguish ' S. ' wuerhoensis from Xinjiangchelys species, we consider it to be a nomen dubium . This new assignment of ' S. ' wuerhoensis expands the temporal range of Xinjiangchelys from the Late Jurassic into the Early Cretaceous in Asia. The majority of the paratypes of ' S. ' wuerhoensis (several shells in dorsal and ventral aspect and skulls) are referred to the basal eucryptodire genus Ordosemys Brinkman and Peng. We establish a new name for these specimens, Ordosemys brinkmania sp. nov. One additional specimen in the type series of ' S. ' wuerhoensis , a skull, is referred to cf. Pantrionychia Joyce, Parham and Gauthier indet.     

SOCIAL BEHAVIOUR AND MASS MORTALITY IN THE BASAL CERATOPSIAN DINOSAUR PSITTACOSAURUS (EARLY CRETACEOUS, PEOPLE'S REPUBLIC OF CHINA)

Abstract:  An exceptionally preserved herd of the ceratopsian dinosaur Psittacosaurus was recovered from the Lujiatun Beds of the Lower Cretaceous Yixian Formation, Liaoning Province, north-east China. This specimen provides the earliest direct evidence of post-nestling gregarious behaviour in this important dinosaur clade. The sediment in which the skeletons occur represents a lahar (volcanic mudflow), indicating that the six individuals present were entombed simultaneously during a catastrophic mass mortality event. Reconstruction of the herd age profile shows it was composed of offspring from at least two clutches, revealing that group fidelity in these dinosaurs extended beyond time spent together in the nest. This demonstrates that sociality appeared much earlier in ceratopsian evolution than is generally acknowledged and that such behaviour preceded the evolution of the elaborate horns and frills seen in derived ceratopsids.     

New radiolarian species from the Upper Cretaceous-Lower Paleogene of the eastern slope of the northern Ural Mountains

Five new radiolarian species, Dictyophimus? orbiculiporosus sp. nov., Spongomelissa imperceptusa sp. nov., Theocoronium puncticulatum sp. nov., Pterocyrtidium porrectum sp. nov., and Tripodiscinus corona sp. nov., from the Campanian-Danian diatomites of the Leplinskaya Formation of the northern Ural Mountains are described. They are useful for stratification and correlation of the Upper Cretaceous and Lower Paleogene beds of the Ural Region of Western Siberia.     

First radiation of Cretaceous planktonic foraminifera with radially elongate chambers at Angles (Southeastern France) and biostratigraphic implications

The study of planktonic foraminifera from the Lower Cretaceous succession at Angles (Southeastern France) directly correlated with ammonites, confirms that the origin of morphotypes with radially elongated chambers occur earlier than previously recorded. In particular, the species Hedbergella semielongata and Hedbergella roblesae bearing subclavate to clavate chambers first appear in the upper Hauterivian, just predating the onset of the oceanic anoxic Faraoni event. Based on these observations, a new zonation is proposed.     

<Emphasis Type="Italic">Salpingoporella</Emphasis>? <Emphasis Type="Italic">popgrigorei</Emphasis>, a new species of Dasycladales (calcareous algae) from the Lower Aptian deposits of Pădurea Craiului (northern Apuseni Mountains,Romania)

A new dasycladalean alga Salpingoporella? popgrigorei n. sp. was identified in P?durea Craiului Mountains (northern Apuseni, Romania) in the Lower Aptian limestone of the Valea Bobdei Member. The new alga was found within the external platform coarse bioclastic facies with fragments of corals, sclerosponges, bivalves (including rudists), gastropods, echinoderms, brachiopods, and bryozoans. The micropaleontological assemblage consists of foraminifera, calcareous algae, rare rivulariacean-type cyanobacteria, and some problematic microfossils. The deposits are Early Bedoulian in age, as clearly indicated by the orbitolinid foraminifera Orbitolinopsis pygmaea, Paracoskinolina sunnilandensis and Palorbitolina lenticularis. Salpingoporella? popgrigorei n. sp. is a medium-sized dasycladalean alga showing funnel-like laterals with an euspondyl arrangement. The laterals consist of two distinctive parts. The proximal part is narrow and flattened. The distal part widens relatively suddenly, and then narrows slightly before the final widening towards the exterior, in the place where the laterals most probably formed an assimilatory cortex. The distinctive features of the new species are represented by the shape of the laterals. The new Salpingoporella best resembles the Upper Hauterivian–Lower Barremian p.p. Salpingoporella genevensis (Conrad), especially due to the quadrangular aspect of the laterals in middle-deep tangential section. However, differences refer to the laterals’ general shape, and to the typical features of the laterals in deep tangential section of Salpingoporella? popgrigorei n. sp.