BONE-HISTOLOGY AS A CLUE IN THE INTERPRETATION OF FUNCTIONAL ADAPTATIONS IN THE THALATTOSUCHIA (REPTILIA, CROCODYLIA)

The histological study of various bones in the families Teleosauridae and Metriorhynchidae reveals common, but also contrasting structural f eatures of the skeleton. Both display a zonal pattern of bone tissue, suggesting a cyclic growth and an ecto-poikilothermic physiology, quit e similar to those of recent crocodiles. However, the Teleosauridae ex hibit no peculiar skeletal specializations related to marine life, whi ch suggests that they had an amphibious, rather than a truly marine ha bitat. Conversely, the skeleton of the Metriorhynchidae displays a cer tain degree of structural lightening, especially obvious in their skul l, but also present in their femora and ribs. This structural speciali zation of the skeleton, together with the supposed physiological regim e of the Metriorhynchidae, had definite bearings on their body trim in water, locomotor capabilities, and activity cycles. These various top ics are discussed with reference to the ecological and eco-physiologic al adaptations of the Thalattosuchia.