Phylogenetic and paleoecological studies of early vertebrates and fossil fishes

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Complete skeletons of fossil fishes found in exceptional fossil deposits yield a wealth of information. In my lab we focus on these deposits to learn about the origins, relationships, mode of life, and anatomical features of species that lived during Silurian and Early Devonian time (400 to 430 million years ago), when early vertebrates with jaws and their jawless relatives were abundant and diverse. These exceptional fossil deposits are in the Mackenzie Mountains, N.W.T. and other parts of northern Canada.    One locality contains at least 60 species of early vertebrates, including jawless forms and early jawed vertebrates related to sharks and bony fishes. Most are complete skeletons. Some of them allow us to examine growth of the skeleton. Others tell us about the evolution of body features such as paired fins, teeth, ears, and guts. These studies involve careful comparisons with fossils found elsewhere in the world and use modern computerized methods of reconstructing the tree of life.    An Eocene (50 million years old) locality contains thousands of specimens of fishes preserved in annual layers of lake sediment. A new approach pioneered by a graduate student from North Dakota reveals growth rates of fishes calculated from fossil scales and vertebrae. Through a postdoctoral fellowship in my lab, we will apply this method to excellent collections from the Eocene locality to learn how growth rates responded to climate changes over centuries and millennia. We will extend these methods to other fossil deposits, learning how growth rates of fishes changed during long-term climate change.    Study of extraordinary deposits shows us more about extinct vertebrates than study of fragments of fossils. The results can then be extended to less favorable situations. Dating of rocks by fragments of fossils and tracing of faunal changes over time will be more reliable when the fossil species and their biology are better known. Fish scales and vertebrae teach us about the biology of ancient species and can lead to predictions about responses of living species during climate change.