Dr. Tom H. Rich

Honorary Research Fellow

Research project

• Late Mesozoic Polar Biotas of Gondwana and the Early Evolution of Mammals, with Emphasis on the Placental and Marsupials.
  Tom Rich's main research interest is the early evolution of mammals, especially those from the Early Cretaceous of Australia, South America and Africa. One long term project in the search to understand the divergence of placental and marsupial mammals and their relationship to monotremes (represented today by the platypus and echnidna) has been carried out along the south coast of Victoria at such sites as Dinosaur Cove to the west of Melbourne and Flat Rocks to the east. The biota that ranges in age from around 105-125 million years and includes a range of vertebrates (pterosaurs, fish, turtles) and importantly a variety of dinosaurs and a single species of labyrinthodont amphibian. Although Australia was far south of its present position at the time these vertebrates lived and joined to Antarctica, the dinosaurs in this fauna show greater similarity to those of Asia than to South America. Adaptations of the hypsilophodontid dinosaurs to the low light intensity of the high latitudes of the time (65-80o S.), which prevailed during the Winter, include enlarged optic lobes of the brain and large eyes. The fact that the hypsilophodonts had evergrowing bones, suggests that this group of dinosaurs, trapped by the great inland sea to the north in these high latitudes with a 3 month long winter,were warm blooded. Alongside the dinosaurs, rare, tiny mammals have been found, known today only from lower jaws. But even from this paultry record it appears that at least two sorts of mammals existed - one related to the living platypus and another to modern placentals, the ausktribosphenids. The current field effort of Tom Rich and his team is to locate skulls of these mammals to resolve just to whom they are related - the mammals that gave rise to us or those that gave rise to the kangaroos. Other research areas of interest to Tom are Cenozoic marsupials, including a palaeoanatomical study of Diprotodon, known from excellent skull material recovered by teams from Monash near Bacchus Marsh in Victoria, and dinosaurs from Chubut Province of Argentina. Understanding the changes that occurred in the biota of Mesozoic and Cenozoic of Gondwana gives insights into climatic and environmental change over the past 150 million years in the southern hemisphere.