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Dinosaurs were the result of the evolutionary changes that took place in reptiles during the Paleozoic Era. This chapter discusses the taxonomy and evidence of dinosaur fossils in California. Dinosaurs arose from one branch of the diapsids, a group of reptiles characterized with two holes in the skull behind the eye socket. One of the most diagnostic traits separating dinosaurs not only from mammals but also from their reptilian relatives is the numerous and unique positioning of the openings and cavities found in the bones of the skull. Because all dinosaurs are diapsids, they have two pairs of main openings behind the eye. The great majority of the dinosaur fossils found in California are from the Cretaceous Period. Dinosaurs from this period have been found from southern Oregon, throughout the length of California, and into northern Baja California. Hadrosaurs were perhaps the most common dinosaur to have inhabited the Pacific coastal region of California, and indeed, more fossil hadrosaurian remains have been found in California than those of any other dinosaur.

This chapter examines the post-glacial population distribution of mayflies in New Zealand. It explains that the mayfly population was isolated after New Zealand was separated from Antarctica and the eastern coast of Australia during the late Cretaceous period, and that the survivors evolved into the present fauna, which includes 42 species. The result of the analysis supports the view that a center of population dispersal of double gilled leptophlebiid was in northern New Zealand and that glaciations in the south resulted in a different pattern of radiation of some single-gilled species. The chapter argues that the pattern of distribution is not necessarily purely the result of biogeographical processes.

This introductory chapter explains the theme of this book, which is about the treeshrews of Borneo. It provides a brief overview of thought on treeshrew taxonomy and phylogeny and the search for their true, but often mistaken, identity. The chapter explains that before 1900, treeshrews were generally thought to be in the order Insectivora and related to the true shrews, but by the first decade of the twentieth century comparative anatomists separated them from that order and proposed a closer relationship to other groups. It suggests that treeshrews are the most closely related living models of the very earliest primate ancestors of the late Cretaceous period, and that their lifestyles can provide a window onto our earliest antecedents, and perhaps a view of why evolution may have taken the direction it did.