Dr. Jason R. Ali  (jrali@hku.hk)  

　　Department of Earth Sciences, University of Hong Kong  

　　Room 602, 10.00 am, Tuesday 17 June  

   

　　Dr Ali’s talk will summarize two biogeographic studies that revolve around the vertebrate suites on Madagascar, the mini-continent in the southwest Indian Ocean (and should thus provide insights into some of the techniques that need to be utilized to understand regional- and global-scale biotic distributions).  

　　The first examines how the extant mammal assemblage, comprising representatives of four orders,came to the island from Africa (lemurs, 60-50 Ma; tenrecs, 42-25 Ma; carnivorans, 26-19 Ma; rodents 24-20 Ma), the analysis drawing upon plate tectonic and palaeo-oceanographic modelling. The second evaluates a much cited hypothesis involving vast land-bridges to explain a wide variety of similar looking vertebrate fossils (non-avian theropod dinosaurs, sauropod dinosaurs, crocodiles, frogs, and mammals) that have been recovered from Upper Cretaceous deposits on many of the crustal blocks that once belonged to Gondwana.Inconveniently, the geological data and geophysical modelling are incompatible with the causeway explanationhence an alternative must be sought. Interestingly,recently published phylogenetic analyses suggest that a number of the clades have common ancestors that pre-date a key phase in Gondwana’s breakup that saw Indo-Madagascar become isolated from Antarctica-Australia-South America at around the Aptian-Albian boundary.  

　　Dr Ali will also be happy to discuss biogeographic problems the audience may have.  

　　 

                                                        脊椎动物演化与人类起源重点实验室&学生会     

　                                                                               2014.6.16