2004 Romer-Simpson Medal Recipient
Robert L. Carroll
I was introduced to paleontology on a spring afternoon, shortly after my fifth birthday. My father has just come home from teaching science in a small town high school in central Michigan .He brought with him a box of fossils he had shown his students that day. They included a trilobite, a few brachiopods, and perhaps some corals. He explained to me that these were the remains of animals that had lived in the sea, a long time ago. I became very excited, especially when he suggested that we might find fossil on our farm.
This was not a very auspicious place to collect fossils, since the entire area was covered by glacial drift, but the glaciers had carried with them rocks represented much of the Paleozoic sequence that made up the Michigan basin, from the Ordovician through the Upper Carboniferous. That summer, my father and I walked behind the horse as it tilled our fields, and picked up what fossils we could find. We visited local gravel pits along the huge esker that ran down the center of the county, giving me an introduction to the Pleistocene glaciation, and clay quarries rich in Carboniferous plants. Although there were no Mesozoic beds within a thousand miles, I soon became interested in dinosaurs as a result of reading Roy Chapman Andrews' tales of his collecting in the Gobi Desert .
I remember very clearly a glorious fall afternoon when I was eight years old, raking leaves with my father, and he asked me what I wanted to be when I grew up. I explained that I wanted to collect and study fossils, especially of animals such as dinosaurs and humans, but I didn't know what the work was called. He replied: "Vertebrate Paleontology." To which I responded: "Then I want to be a vertebrate paleontologist." This desire was further kindled by receiving as a Christmas present that year, the left femur of Allosaurus, thanks to the generosity of Dr. Colbert, whom my father had told about my interest in vertebrate paleontology.
The high point in my childhood was a trip with my father to the famous fossil bearing localities of the western United States. These included the Eocene Green River fish beds of Fossil, Wyoming, the White River Oligocene of the badlands of South Dakota, and the Bone Cabin Quarry of the Upper Jurassic Morrison Formation. By the age of 12, I had amassed a collection that filled two rooms of the family barn, and declared this "The Mason Museum of Natural History." I even put up a sign on the highway that ran through the farm.
I received my BSc from Michigan State University, majoring in Geology, but taking as much biology as I could fit in. The summer before college I worked at the University Museum, spending much of my time preparing sauropod limbs and vertebrae. The next summer was spent in western Kansas with Claude Hibbard, collecting, screen washing and picking Pleistocene micromammals. The following year, I was a field assistant with Dick Seltin, in the Lower Permian Redbeds of north central Texas.
Because Dick Seltin had been a student of E. C. Olson, I applied to do graduate work at the University of Chicago, and was all set to go when I suddenly thought, why shouldn't I go to Harvard, and study with Dr. Romer, whose second edition of Vertebrate Paleontology I had read in college? He was clearly the best teacher I could possibly find and Harvard the best environment for graduate studies.
I actually knew very little about vertebrate paleontology when I began graduate school, but was happy to accept Dr. Romer's offer of a thesis on dissorophids, represented by a drawer filled with irregular lumps of red clay from the Texas Permian that had been collected by Lew Price. He must have had x-ray vision to see fossils through the covering matrix, but they proved to be a treasure trove of anatomical detail, illustrating the early diversity of this family.
Harvard had an extraordinary group of professors in the fields of paleontology and evolutionary biology at that time — Brian Patterson, working on advanced mammal-like reptiles and Mesozoic mammals; Ernest Williams, herpetology; Ernst Mayr, evolution; Darlington, biogeography; Harry Whittington, invertebrate paleontology and many others. But the most wonderful surprise was the arrival that year from Columbia University of George Gaylord Simpson. Many of these professors met each afternoon in the vertebrate paleontology prep room in the basement of the MCZ to have coffee and cigarettes. This provided a wonderful opportunity for the graduate students to hear of the latest discoveries and meet visiting scientists.
It was ironic that I was doing a thesis on dissorophids at the same time that Parsons and Williams were hatching the Lissamphibian hypothesis. The very animals that prior paleontologists, including D. M. W. Watson, had put forward as the possible ancestors of frogs were now seemingly dismissed from that role because they did not have any of the unique shared derived characters that Parson and Williams had proposed for a putative common ancestor of frogs, salamanders and caecilians. Rather, my thesis dealt with dissorophids strictly within the context of Paleozoic labyrinthodonts.
Another area of research that really excited me at Harvard was Brian Patternson's investigation of the origin of mammals, based on recently discovered cynodonts from South America and Lower Cretaceous therian teeth from Texas. But the foundation for my future research was provided by Dr. Romer\'s suggestion of a study of Dawson's collection of early tetrapods from the Carboniferous tree stump fauna of Joggins, Nova Scotia, at Redpath Museum, McGill University. This study was focussed on two interrelated problems, the origin of reptiles and the nature of microsaurs, which had long been confused with early amniotes.
The great diversity of the long-neglected Joggins fauna not only enabled me to find answers to both of these problems, but introduced me to many other groups of Paleozoic tetrapods. During the second half of my postdoctoral studies, taken at the British Museum (Natural History), I decided to undertake a comprehensive study of the entire Order Microsauria, which took another 15 years. This expanded further into investigations of all lepospondyl amphibians, as well as key Carboniferous labyrinthodonts. During a sabbatical in South Africa, I pursued the later radiation of stem amniotes into their putative descendants among later Permian and early Triassic diapsids. Fossils of primitive aquatic diapsids from the late Permian of Madagascar that I saw in the Cape Town Museum led me to study larger collections from this locality in Paris and a private museum in Brittany. These, in turn, resulted in studies of primitive sauropterygians and pleurosaurs in other European institutions.
By this time, I had been joined at McGill by the first of a succession of extremely talented and enthusiastic undergraduates, graduate students, postdoctoral fellows, and the most talented artist and preparator, Pam Gaskill, all of whom interacted so to cover an extensive portion of early tetrapod evolution. I am pleased to say that most of these students have found museum and academic positions in the United States and Canada, and are now producing a new generation of vertebrate paleontologists. Teaching also provided the impetus for writing Vertebrate Paleontology and Evolution and Patterns and Process of Vertebrate Evolution.
Periodically, during the past 45 years of research on Paleozoic amphibians, my students and I have written papers concerned with the possible nature of their relationships with modern frogs, salamanders and caecilians. Now, I am spending much of my time on this single, complex problem, trying to integrate what my students, colleague, and I had learned about ancient amphibians, with what other have described of the modern groups. This requires a much different analytical approach than others have used in recent years — specifically the integration of knowledge of all aspects (primitive and derived) of the functional and structural anatomy, physiology, way of life, and especially the sequence of ontogenetic development that can be gained from modern and extinct taxa. The goal is not simply to achieve the most parsimonious three taxon statement, but rather to establish the specific sequence of evolutionary changes that have led to the modern orders. This study will also provide the background for a book, for a fairly wide audience, covering the entire history of amphibians.
Another project, being initiated with the help of students and colleagues, is a description of all the elements — fish, early tetrapods, invertebrate trace fossils, and plants — of the biota of the Lower Carboniferous Horton Formation of Nova Scotia, from which we have been collecting over the past 40 years. Bit by bit we have assembled the scattered remains of the earliest Carboniferous terrestrial vertebrates, hundreds of their footprints, gigantic rhizodontids, a diversity of acanthodians, palaeoniscoids and occasional shark spines that will help us to understand many aspects of the environment and way of life of early terrestrial vertebrates.
All these activities continue to give me great pleasure, and I hope contribute in some way to the understanding of the evolution of vertebrates. I thank the Society for providing a professional environment where I can share my enthusiasm for all things paleontological and evolutionary, and for the medal that also honors Drs. Romer and Simpson who contributed so much in founding this society, and to my own training.
Photo courtesy of Robert L. Carroll.