Osteology and functional morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea) based on new material in the Yale Peabody Museum

Two incompfete skeletons and other isolated bones of Dimorphodon macronyx (Buckland), an early rhamphorhynchoid pterosaur from the Lower Lias (Hettangian) of England, have remained undescribed in the collections of the Peabody Museum of Natural History since their acquisition by O. C. Marsh over a century ago. Some of this material comes from Aust Cliff near Bristol, and therefore constitutes the first record of Dimorphodon outside the Lyme Regis area of Dorset. The two individuals are smaller than those in the British Museum (Natural History) described by Owen, and juvenile proportions characterize both cranial and postcranial remains. Much of the material is three-dimensional and has been prepared from its matrix; it provides some of the fullest structural and functional information available for any pterosaur. A particularly well-preserved humerus gives insight into the articulations and folding of the wing, and two sets of distal tarsals demonstrate the mesotarsal flexion of the ankle. Comparison with more extensive but less fully prepared material in the British Museum (Natural History) allows some osteological identifications to be established or corrected; it also provides the basis for a new assessment of structure and function in pterosaurs. The forelimbs could not have moved parasagittally but were well suited for an active flight stroke. The hindlimbs were positioned and moved like those of bipedal dinosaurs and birds. The feet were digitigrade and were not adapted to hang fromtreesorcliffs.Comparativeosteology indicates that these features and abilities conform very well to an advanced archosaurian Bauplan seen in dinosaurs and birds

Truth or Consequences? Engaging the “Truth” of Evolution

Paleontologist Kevin Padian reviews "Why Evolution Is True," which presents the vast, varied, and unquestionably robust evidence that shows how evolution makes sense of biology

Measuring Biodiversity and Extinction – Present and Past

How biodiversity is changing in our time represents a major concern for all organismal biologists. Anthropogenic changes to our planet are decreasing species diversity through the negative effects of pollution, habitat destruction, direct extirpation of species, and climate change. But major biotic changes – including those that have both increased and decreased species diversity – have happened before in Earth’s history. Biodiversity dynamics in past eras provide important context to understand ecological responses to current environmental change. The work of assessing biodiversity is woven into ecology, environmental science, conservation, paleontology, phylogenetics, evolutionary and developmental biology, and many other disciplines; yet, the absolute foundation of how we measure species diversity depends on taxonomy and systematics. The aspiration of this symposium, and complementary contributed talks, was to promote better understanding of our common goals and encourage future interdisciplinary discussion of biodiversity dynamics. The contributions in this collection of papers bring together a diverse group of speakers to confront several important themes. How can biologists best respond to the urgent need to identify and conserve diversity? How can we better communicate the nature of species across scientific disciplines? Where are the major gaps in knowledge about the diversity of living animal and plant groups, and what are the implications for understanding potential diversity loss? How can we effectively use the fossil record of past diversity and extinction to understand current biodiversity loss

Hip joint articular soft tissues of non-dinosaurian Dinosauromorpha and early Dinosauria: evolutionary and biomechanical implications for Saurischia

Dinosauromorphs evolved a wide diversity of hind limb skeletal morphologies, suggesting highly divergent articular soft tissue anatomies. However, poor preservation of articular soft tissues in fossils has hampered any follow-on functional inferences. We reconstruct the hip joint soft tissue anatomy of non-dinosaurian dinosauromorphs and early dinosaurs using osteological correlates derived from extant sauropsids and infer trends in character transitions along the theropod and sauropodomorph lineagues. Femora and pelves of 107 dinosauromorphs and outgroup taxa were digitized using 3D imaging techniques. Key transitions were estimated using maximum likelihood ancestral state reconstruction. The hips of dinosauromorphs possessed wide a disparity of soft tissue morphologies beyond the types and combinations exhibited by extant archosaurs. Early evolution of the dinosauriform hip joint was characterized by the retention of a prominent femoral hyaline cartilage cone in post-neonatal individuals, with the cartilage cone independently reduced within theropods and sauropodomorphs. The femur of Dinosauriformes possessed a fibrocartilage sleeve on the metaphysis, which surrounded a hyaline core. The acetabulum of Dinosauriformes possessed distinct labrum and antitrochanter structures. In sauropodomorphs, hip congruence was maintained by thick hyaline cartilage on the femoral head, whereas theropods relied on acetabular tissues such as ligaments and articular pads. In particular, the craniolaterally ossified hip capsule of non- Avetheropoda neotheropods permitted mostly parasagittal femoral movements. These data indicate that the dinosauromorph hip underwent mosaic evolution within the saurischian lineage and that sauropodomorphs and theropods underwent both convergence and divergence in articular soft tissues, correlated with transitions in body size, locomotor posture, and joint loading

Darwin, Dover, and Intelligent Design

[EN] The newest face of American creationism is “intelligent design”, a sociopolitical movement that appeals to people’s fear that evolution is atheistic. ID supposes that some biological structures are so complex that they cannot have been assembled by natural processes; therefore, when we recognize such “irreducible complex” features, they must have been achieved miraculously by an “intelligent designer”. Although ID proponents insist that their view is scientific, it has no empirical evidence and is supported by no peer-reviewed publications; it has been rejected by the scientific community. Nevertheless its proponents have attempted to introduce it into school systems as an “alternative” to traditional evolutionary science. The attempt to do so in the schools of Dover, Pennsylvania in 2004 resulted in a Federal trial that rejected ID as science, labeling instead as religiously motivated. This has slowed but not stopped creationists. Their continuing strategies are to insist that we “teach the controversy” about evolution (where none exists scientifically), to teach “critical thinking” to students (by which they mean to criticize ideas they don’t like), and to allow “academic freedom” for creationist teachers to introduce any materials they like into classrooms.[ES] La cara más moderna del creacionismo americano es el “diseño inteligente” (DI), un movimiento sociopolítico que apela al miedo de la gente basándose en que la evolución implica ateísmo. El DI supone que algunas estructuras biológicas son tan complejas que no pueden ser el resultado de un proceso natural, de manera que cuando nos encontramos con esas características “irreductiblemente complejas”, deben ser el resultado de la acción milagrosa de un “diseñador inteligente”. Aunque los defensores del DI insisten en que su perspectiva es científica, no tienen evidencia empírica que lo corrobore y no está apoyada por publicaciones arbitradas; es más, ha sido rechaza por la comunidad científica. Sin embargo, los defensores del DI han intentando que el tema se imparta como parte del currículo dentro del sistema educativo, como una “alternativa” a la ciencia evolucionista tradicional. El intento de hacerlo en las escuelas de Dover, Pennsylvania, en 2004 terminó en un proceso judicial federal que rechazó el DI como ciencia, tachándolo de estar religiosamente motivado. Esto ha ralentizado pero no detenido a los creacionistas. Su estrategia consiste en insistir en que la evolución que enseñamos es controvertida (cuando esto no es cierto en el panorama científico), enseñando “pensamiento crítico” a los estudiantes (cuando lo que realmente quieren decir es que se critica ideas que nos les gustan), y que es preciso permitir la “libertad académica” para los profesores creacionistas que deseen emplear cualquier material en sus clases