An enantiornithine bird from the Lower Cretaceous of Queensland, Australia
Current classification of birds recognizes four subclasses: the Archaeornithes, the Enantiornithes, the Odontornithes and the Neornithes. Three of these subclasses were proposed during the nineteenth century, but the Enantiornithes was proposed only five years ago, based on material from the Lecho Formation (Maas-trichtian) of Salt a Province in Argentina1. Further material from Asia (Mongolia) and North America (Mexico) has been referred to the Enantiornithes2, all of it from the Campanian. Now, in addition, a small tibiotarsus found in the Lower Cretaceous (Albian) of Queensland not only represents the first bony material of Mesozoic birds from Australia, but is also the first reported occurrence of an enantiornithine bird in the Lower Cretaceous.
A Third Specimen of a Lower Cretaceous Feather from Victoria, Australia
Talent et al. (Emu 66(2):81, 1966) described the first two feathers to be discovered in Australian Mesozoic strata. These were found in a band of laminated siltstone-claystone near the hamlet of Koonwarra in South Gippsland. This bed is believed to represent the shallow arm of a freshwater lake and contains a biota of insects, crustaceans, a limulid, five genera of fish, and a varied flora. During field work in 1966 a third feather was discovered in the same stratum as the two previously described specimens, by a member of the Monash University, Department of Zoology party. The specimen (National Museum of Victoria P.26059AB; fig. 1) is a complete, small, lanceolate contour feather. It is 15 mm in length and reaches a maximum breadth of 6 mm at a point 7 mm from the base of the calamus. The calamus measures 0.5 mm across the base and is broader than the shaft, which narrows above the calamus and tapers steadily toward the distal extremity. The vanes, which taper to a point distally, consist of tapering barbs, those of the outer vane being shorter than those of the inner. The feather is, therefore, asymmetric. The barbs are much finer than the main shaft, except at the distal extremity of the feather where they are of comparable width. The proximal barbs are set on the shaft at an angle of 450 which gradually decreases to about 150 in the distal region of the feather. The vanules consist of long, delicate barbules set at about 15-200 to the barbs. The gently tapering distal barbules are well preserved and may in places be observed to interlock HM,,
Far-field dispersal modeling for fuel-air-explosive devices
A computer model for simulating the explosive dispersal of a fuel agent in the far-field regime is described and is applied to a wide variety of initial conditions to judge their effect upon the resulting fuel/air cloud. This work was directed toward modeling the dispersal process associated with Fuel-Air-Explosives devices. The far-field dispersal regime is taken to be that time after the initial burster charge detonation in which the shock forces no longer dominate the flow field and initial canister and fuel mass breakup has occurred. The model was applied to a low vapor pressure fuel, a high vapor pressure fuel and a solid fuel. A strong dependence of the final cloud characteristics upon the initial droplet size distribution was demonstrated. The predicted fuel-air clouds were highly non-uniform in concentration. 18 refs., 86 figs., 4 tabs.