The Osteology of the Basal Archosauromorph Tasmaniosaurus triassicus from the Lower Triassic of Tasmania, Australia

Proterosuchidae are the most taxonomically diverse archosauromorph reptiles sampled in the immediate aftermath of the Permo-Triassic mass extinction and represent the earliest radiation of Archosauriformes (archosaurs and closely related species). Proterosuchids are potentially represented by approximately 15 nominal species collected from South Africa, China, Russia, Australia and India, but the taxonomic content of the group is currently in a state of flux because of the poor anatomic and systematic information available for several of its putative members. Here, the putative proterosuchid Tasmaniosaurus triassicus from the Lower Triassic of Hobart, Tasmania (Australia),is redescribed. The holotype and currently only known specimen includes cranial and postcranial remains and the revision of this material sheds new light on the anatomy of the animal, including new data on the cranial endocast. Several bones are re-identified or reinterpreted, contrasting with the descriptions of previous authors. The new information provided here shows that Tasmaniosaurus closely resembles the South African proterosuchid Proterosuchus, but it differed in the presence of, for example, a slightly downturned premaxilla, a shorter anterior process of maxilla, and a diamond-shaped anterior end of interclavicle. Previous claims for the presence of gut contents in the holotype of Tasmaniosaurus are considered ambiguous. The description of the cranial endocast of Tasmaniosaurus provides for the first time information about the anatomy of this region in proterosuchids. The cranial endocast preserves possibly part of the vomero-nasal (= Jacobson's) system laterally to the olfactory bulbs. Previous claims of the absence of the vomero-nasal organs in archosaurs, which is suggested by the extant phylogenetic bracket, are questioned because its absence in both clades of extant archosaurs seems to be directly related with the independent acquisition of a non-ground living mode of life

Morphological aspects of the development of swimming and feeding functions in the milkfish Chanos chanos

Contribution No. 213 of the SEAFDEC Aquaculture Department.Development of swimming and feeding abilities based on morphological development of larval and early juvenileChanos chanos was investigated. In larvae smaller than about 6.5 mm SL, mechanical supports of fins and branchial arches were in a primordial stage of development. Supports and rays of the vertical fins and branchial arches rapidly developed from 6.5 mm SL, and all components appeared by about 10.5 mm SL. Thereafter body depth proportion changed and the supports and rays of the paired fins and gill-rakers developed. These developmental events were nearly or totally completed by about 17 mm SL, and we concluded that the larvae transformed to juveniles at this size. By this time, the mode of swimming of the fish shifted from undulating locomotion to caudal propulsion and that of feeding from swallowing paniculate food to filtering and concentrating substrate food matters using gill-rakers and the epibranchial organ. One of the most characteristic, and well-known, phenomena in the life history ofChanos chanos is the mass occurrence in the surf zone of postlarvae of a limited size range. In view of the scheme of the development of mechanical supports of the body and fins, they may acquire a swimming ability strong enough to move against the current only upon reaching about 10.5 mm SL, and if active shoreward migration of the larvae occurs, it is only during the late period of their journey from the spawning grounds to the shore. The sudden disappearance from the surf zone of larvae larger than 15–16 mm SL is obviously related to a change in food habit