A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation,Alberta, Canada

A recently discovered articulated partial skeleton of Ornithomimus from the Upper Cretaceous Dinosaur Park Formation of Alberta, Canada is remarkable in the extent and quality of preservation of integumentary structures including feathers. It is the first ornithomimid to preserve a tail bearing extensive plumaceous feathers that are slightly more elongate in comparison to those present on the remainder of the body. However, the underside of the tail and the hind limb distal to the middle of the femur appear devoid of plumage. Overall, the plumage pattern in Ornithomimus is similar to that of Struthio camelus (ostrich) and other large palaeognaths, indicating a probable function in thermoregulation. The specimen also preserves the body outline around the legs, including a skin contour anterior to the femur, analogous to skin webs in extant birds. Whereas the knee web of birds bridges the knee to the abdomen, in Ornithomimus it spans from the mid-femoral shaft to the abdomen, and is herein referred to as an anterior femoral web. This is the first report of such soft tissue structures in non-avian theropods. It may indicate that the resting position of the femur was positioned more anteroventrally in ornithomimids than in most theropods, and in that sense may have been transitional to the situation in modern birds.     

Quantitative monitoring of aquatic humic substances in Lake Biwa,Japan, using the DAX-8 batch method based on carbon concentrations

Aquatic humic substances (AHS) have been intensively studied because they have a number of significant biogeochemical functions in water chemistry. In order to evaluate such functions, which are regulated by their quantity and quality, a quantitative understanding of AHS is necessary. This study shows the seasonal and vertical changes in the AHS concentration in Lake Biwa, the largest monomictic lake in Japan, over 4 years. The concentration of dissolved organic matter carbon (DOM-C) and AHS carbon (AHS-C) ranged from 0.85–1.6 mg C/l and 0.32–0.71 mg C/l, respectively. The percentages of AHS-C in the DOM-C ranged from 32% to 65%. At all depths, the DOM-C decreased and the AHS-C slightly increased or remained at nearly the same level, suggesting that the quality of the water may have changed mainly due to changes in the composition of the organic matter. Although the AHS-C to DOM-C ratio fluctuated and had no seasonal tendency, the average AHS-C ratio increased during the 4 year monitoring period. Because AHS can influence the entire food web starting with phytoplankton, unraveling the mechanism by which they accumulate remains an important goal.