Kevin Padian's main research areas fall into the following categories. Students are welcome to do research in these areas, or to explore other areas of research related to the evolution of major adaptations within vertebrates.
The Origins of Flight
One of the most pressing evolutionary problems is how new major adaptations (which often "define" major evolutionary groups) get started. Through a syntheses of phylogenetic, functional, and comparative morphological evidence, I try to assemble the best-supported evolutionary sequences available, and to reconstruct the steps by which major adaptations are assembled. My principal interest is flight, because it has so many physical and physiological restrictions, which have been met by only three groups of vertebrates (pterosaurs, birds, and bats). Hypotheses about the origins of major adaptations need to be rooted in rigorous functional studies, and tested against well-supported phylogenetic analyses of the groups in question, as well as other important lines of evidence that bear on a question.
The origin of birds and the origin of their flight are questions that lend themselves particularly well to this kind of analysis, because the origin of birds from theropod dinosaurs is so well understood, and the sequential assembly of features related to the evolution of flight in birds (i.e., the evolution of the flight stroke) is becoming better and better known.
Birds and Other Dinosaurs
Much of my work focuses on the origin of birds from theropod dinosaurs; in particular I am interested in the mechanical and adaptational aspects of this change, which should be informed and tested by recourse to hypotheses of evolutionary patterns (cladograms).
The Beginning of the Age of Dinosaurs
Although I work generally on Mesozoic vertebrate paleontology, I am most interested in the changes that took place around the Triassic Jurassic boundary. At that time, the last Permian holdovers disappeared from the terrestrial fauna; many new groups of vertebrates, especially archosaurs, appeared, flourished briefly, and disappeared; and the major groups of the living terrestrial vertebrate fauna (including lissamphibians, turtles, mammals, sphenodontians, squamates, and crocodiles, as well as pterosaurs and dinosaurs) first appeared.
Systematics, functional morphology, and flight of pterosaurs. Pterosaurs interest me because they were the first vertebrates to gain powered flight, they were among the closest known relatives to dinosaurs, and they persisted for 150 million years. They provide many interesting keys to the evolution of posture, locomotion, homeothermy, and vertebrate adaptation in the early Mesozoic Era, and still pose many intriguing challenges to vertebrate biologists.
Histology and constructional morphology of the bones of extinct reptiles. Bone structure and histology provide important clues to reconstructing the metabolism, growth, and adaptations of extinct animals. Comparative bone histology in a phylogenetic series of taxa and some ontogenetic series can provide the best picture of age, growth, and metabolism, and engineering design helps to understand functional adaptations of bone. Our histology work is in conjunction with Drs. Jack Horner (Museum of the Rockies) and Armand de Ricqles (University of Paris), and bioengineering with Dr. Dennis Carter (Stanford) and his associates.
My colleague Paul Olsen (Columbia University) and I have studied the stance and gait of living and extinct reptiles, including crocodiles, pterosaurs, basal theropod dinosaurs, Komodo dragons, and birds, in an effort to understand the factors that contribute to the formation of footprints. Our work focuses on the integration of anatomy, limb kinematics, and substrate competence, following Don Baird's axiom that a footprint is not a static record of a foot, but a dynamic record of that structure performing in a certain way on a given substrate. We have attempted to depict these influences using the accompanying ternary diagram. In this example, the trackway Pteraichnus shows strong influence of the incompetent substrate in which it is made. The anatomy is not clearly preserved nor impressed, partly because there was considerable substrate disturbance during the forelimb cycle.
The History of Evolutionary Thought
The years leading up to the publication of Darwin's Origin of Species are important to understand if Darwin's own magnum opus is to be understood. Central figures such as Richard Owen are seldom read or studied by biologists today, but Owen's views dominated biology in his time and his effects are still felt on textbook biology today, as well as on some of our principal evolutionary concepts, such as homology. In my work, I like to draw out some of the terms of debate in Victorian England and relate them to similar questions in our own day.