Celebrating 100 Years
Alan H. Cheetham: Invertebrate Paleontologist
Alan H. Cheetham was born in El Paso, Texas. After spending his first two years in Chihuahua, Mexico, he grew up in Taos, New Mexico; there he cultivated an early interest in chemistry and geology when his father and grandfather became involved in an effort to revive an old gold mine in the mountains north of town. While an undergraduate at the New Mexico Institute of Mining and Technology, he became fascinated with the marine invertebrate fossils that he encountered while doing field work for his senior thesis in the mountains of central New Mexico. Upon graduating, he went to Louisiana State University (LSU) for his master’s degree, pursuing his new interest in paleontology and invertebrate zoology. He continued teaching at LSU while completing his doctorate in geology and paleontology at Columbia University as one of the first students awarded a National Science Foundation (NSF) fellowship in a national competition. He was again awarded an NSF fellowship for a year at the Natural History Museum in London in 1961-62. In 1964-65, he taught as a guest professor at the University of Stockholm in Sweden, before coming to the Smithsonian Institution in 1966.
Cheetham’s research concerns Bryozoa, small, aquatic invertebrates—with an appearance that ranges from moss-like to miniature coral-like—which reproduce both sexually and by budding. Budding produces clones of genetically identical individuals that ordinarily remain physically connected within an aggregate, called a colony, but can become separated to produce new colonies, similar to those formed sexually. Colonies can be free living, or in the form of encrusting sheets, or erect branching miniature tree-like forms attached to stones, aquatic plants, or other invertebrates. Fossilized skeletons of these animals occur profusely in many marine sedimentary deposits dating as far back as the Ordovician Period, almost 500 million years ago. As a consequence of their extensive fossil record a
nd diversity of form, they have proven important in deciphering details of rates and modes of evolution, as well as reconstructing interrelationships of organisms in ancient marine environments.
It was while he was at Louisiana State University, in the heart of the Gulf Coast region, that Cheetham’s focus turned to the interval of the bryozoan fossil record to which he would devote his career: the Cenozoic Era, covering the last 65 million years, during which the group called Cheilostomata, or cheilostomes, became the dominant Bryozoa, as they remain today. Although much work had been done on this group in the late 19th and early 20th centuries, it was far from complete and, in some cases, based on outmoded principles.
Cheetham’s work on the Bryozoa from Eocene deposits (approximately 40 million years old) in Florida, Alabama, and Mississippi, published in 1963, and on those from deposits of equivalent age in southern England, published in 1966, qualified him to be one of the last curators hired under the National Oceanographic Program, initiated under the Kennedy administration in anticipation of a need for specialists on groups of organisms likely to become available for study in material collected on and under the ocean floor by a variety of projects. Particularly exciting to paleontologists was the Deep Sea Drilling Project designed to extract extensive cores through sediments under the deep ocean with technologies then only recently developed. The results would not only help in understanding ocean history, but also provide fossils not previously accessible for study.
Over the course of his career in the National Museum of Natural History’s Department of Paleobiology, Cheetham authored and edited a number of book-length publications, including the textbook Fossil Invertebrates (with R. S. Boardman and A. J. Rowell), as well as numerous journal articles and book chapters. He served as advisor to doctoral and post-doctoral students, both at the Smithsonian and in universities. During his time at the University of Stockholm in the mid-1960s, he convened a gathering of experts on Bryozoa from across Europe to found the International Bryozoology Association, a group that has met every three years since, and for which some of his students have served as president, as he had during the association’s formative years.
Since 1990, he has been active with the Panama Paleontology Project, a project to collect and document fossils from ancient deposits on both sides of the Central American isthmus and use them in research on evolutionary and environmental changes over time. And since 1996, he has been the coordinator of bryozoan contributors for the Neogene Marine Biota of Tropical America, an online database of Tropical American biodiversity from the last 25 million years. With Dr. Jeremy Jackson, co-founder of the Panama Paleontology Project, Cheetham has been involved in a series of studies—based in large part on material from these two sources—that have tested the controversial evolutionary theory of punctuated equilibrium. Their results have proven interesting to both evolutionary biologists and paleontologists and are now included in textbooks on evolution as well as on principles of paleontology.An active member of many scientific societies and a fellow of the American Association for the Advancement of Science, he has been recognized with the Paleontological Society Medal (2001) and the Raymond C. Moore Medal for Excellence in Paleontology (1997). Alan and his wife Marjorie have been retired and living in Santa Fe, New Mexico, since 2002. He nevertheless continued to work with his colleagues at the Museum, up until the time his last paper was published in 2007.
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