Diversification of Neoaves: integration of molecular sequence data and fossils

Patterns of diversification and timing of evolution within Neoaves, which includes almost 95% of all bird species, are virtually unknown. On the other hand, molecular data consistently indicate a Cretaceous origin of many neoavian lineages and the fossil record seems to support an Early Tertiary diversification. Here, we present the first well-resolved molecular phylogeny for Neoaves, together with divergence time estimates calibrated with a large number of stratigraphically and phylogenetically well-documented fossils. Our study defines several well-supported clades within Neoaves. The calibration results suggest that Neoaves, after an initial split from Galloanseres in Mid-Cretaceous, diversified around or soon after the K/T boundary. Our results thus do not contradict palaeontological data and show that there is no solid molecular evidence for an extensive pre-Tertiary radiation of Neoaves

To fly or not to fly: high flight costs in a large sea duck do not imply an expensive lifestyle

A perennial question in ornithology is whether flight has evolved mostly to facilitate access to food or as an anti-predator strategy. However, flight is an expensive mode of locomotion and species using flight regularly are associated with an expensive lifestyle. Using heart rate (HR) data loggers implanted in 13 female common eiders (Somateria mollissima), our objective was to test the hypothesis that a high level of flight activity increases their energy budget. We used the long-term recording (seven months) of HR as an index of energy expenditure and the HR flight signature to compile all flight events. Our results indicate that the eider is one of the thriftiest volant birds with only 10 minutes of flight time per day. Consequently, we were not able to detect any effect of flight activity on their energy budget despite very high flight costs (123–149 W), suggesting that flight was controlled by energy budget limitations. However, the low flight activity of that species may also be related to their prey landscape requiring few or no large-scale movements. Nevertheless, we suggest that the (fitness) benefits of keeping flight ability in this species exceed the costs by allowing a higher survival in relation to predation and environmental harshness

FARKLI ÜRETİM YÖNTEMLERİ İLE ÜRETİLEN MİNİ İNSANSIZ HAVA ARAÇLARINDA ÜRETİM YÖNTEMİNİN PERFORMANS ÜZERİNDEKİ ETKİSİ

The relationship between wing kinematics, wing morphology and the brachial index of birds (BI=humerus length/ulna length) was examined. BI was found to differ between three groups of birds, which were classified on the basis of similar wing kinematics. In addition, a comparative analysis of a large dataset, using phylogenetically independent contrasts, suggested a significant, albeit weak, correlation between BI and four measures of wing morphology (wing loading, wing area, wing length and aspect ratio). Although wing kinematics and wing morphology are both correlated with BI in birds, the dominant selective pressure upon this ratio is probably wing kinematics. The previously identified clade specificity of BI within Neornithes is most likely because birds with similar BIs fly with kinematic similarity and closely related birds have similar flight styles. A correlation between BI and wing kinematics means that it may be possible to characterize the wing beat of fossil birds. A more robust relationship between wing morphology and BI may emerge, but only after the relationship between wing kinematics and BI is quantified. A comparative and quantitative study of wing-bone anatomy and wing kinematics is a priority for future studies of avian wing-skeleton evolution and functional morphology.<br/

At the root of the early penguin neck: a study of the only two cervicodorsal spines recovered from the Eocene of Antarctica

The spinal column of early Antarctic penguins is poorly known, mainly due to the scarcity of articulated vertebrae in the fossil record. One of the most interesting segments of this part of the skeleton is the transitional series located at the root of the neck. Here, two such cervicodorsal series, comprising reinterpreted known material and a new specimen from the Eocene of Seymour Island (Antarctic Peninsula), were investigated and contrasted with those of modern penguins and some fossil bones. The new specimen is smaller than the counterpart elements in recent king penguins, whereas the second series belonged to a large-bodied penguin from the genus Palaeeudyptes. It had been assigned by earlier researchers to P. gunnari (a species of “giant” penguins) and a Bayesian analysis—a Bayes factor approach based on size of an associated tarsometatarsus—strongly supported such an assignment. Morphological and functional studies revealed that mobility within the aforementioned segment probably did not differ substantially between extant and studied fossil penguins. There were, however, intriguing morphological differences between the smaller fossil specimen and the comparative material related to the condition of the lateral excavation in the first cervicodorsal vertebra and the extremely small size of the intervertebral foramen located just prior to the first “true” thoracic vertebra. The former feature could have resulted from discrepancy in severity of external pneumatization. Both fossils provided valuable insights into the morphology and functioning of the axial skeleton in early penguins