We announce with sadness the passing of John Ryan Bolt, Emeritus Curator of Fossil Amphibians and Reptiles. John was a leading expert on the evolutionary transformation of fish-like vertebrate animals as they emerged from water and became four-footed tetrapods adapted to life on land. After obtaining a Bachelor’s degree at Michigan State University, John was accepted into the innovative Paleozoology program at the University of Chicago, where he studied with professors and students whose prominence helped define vertebrate paleontology into the early years of the 21st century. In 1968, after being awarded the first Ph.D. from the Committee on Evolutionary Biology, John taught for a period at the University of Illinois Medical Center before joining the Field Museum in 1972. At the Museum, he built an impressive body of scientific work on early tetrapods, especially fossil amphibians from about 360 to 250 million years ago, and began a wider consideration of vertebrate evolution. For many years, he volunteered as treasurer and later advised on financial oversight for the Society of Vertebrate Paleontology; in 2006, he received the Gregory Award for his dedicated service. Though still working up to the end, he officially retired in 2008, having brought compelling leadership to the Museum and important contributions to the field of vertebrate paleontology.
John’s scientific work was absolutely thorough and meticulous, and his fossil discoveries overturned some older paradigms of vertebrate evolution. His exacting methods carried over into his development of “fine preparation” labs for fossils, using binocular microscopes, pin vises, and dental turbines, and the Field Museum became a world leader in this style of preparation. He developed synergistic collaborations with two colleagues, Bob DeMar from the University of Illinois and Eric Lombard from the University of Chicago. The first of these collaborations focused on the structure and replacement of teeth. John discovered fossils from Fort Sill, Oklahoma, that provided a unique piece of evidence from different forms of teeth that convincingly linked Paleozoic fossils into an inclusive group with modern amphibians. Biologist Eric Lombard had been working on the functional biology of the ear in frogs, and teamed up with John in a series of papers that revolutionized scientists’ understanding of the evolution of hearing. Their work focused on the structures of the middle ear in early amphibians, reptiles, and later-evolving vertebrates. Hearing in aquatic animals is optimized for the amplitude and speed of sound underwater, where both are greater than sound in air. The earlier paradigm stated that general eardrum structure (the tympanic membrane and related parts) had evolved only once in a common ancestor and descended with modifications to all later land-dwelling vertebrate groups. Bolt and Lombard’s painstaking comparative studies of skeletal structures in fossil and modern vertebrates showed instead that the middle ear structures had evolved independently several times. The middle ear of mammals is quite different from those of reptiles and amphibians. Moreover, these influential discoveries have been corroborated by biologists studying the embryonic development of ear structures among different living vertebrates. One last series of discoveries comes from the 324-million-year-old Delta fauna in Iowa, one of the most important and best-preserved windows into the early diversity of amphibians and reptiles. The top photo shows John with “Rex the wonder amphibian,” of the genus Whatcheeria, one of many groups of early tetrapods from this fauna that are still being described.
Who was John the person? He was a quiet and modest man, yet his sharp wit could be wickedly funny. He was tolerant of the wide variety of human behavior and quirks he encountered in others. John laughed with us about his own quirks, too, like his beloved harem of exotic bicycles. He would arrive from Hyde Park one day with a folding bike, the next with a recliner, and on and on. He had ravenous curiosity and read widely on history, politics, and finance, and was a dedicated connoisseur of good food. John was always ready for an engaging discussion on science or anything else. Above all, this was a man with an extraordinary sense of integrity and responsibility. During his two terms as Geology Chair (1981–1990), John pushed aside his own personal ambitions and focused intently on rebuilding the paleontological component of the department. Under his vision and sensible management, a stellar group of new curators—Peter Crane, Lance Grande, Scott Lidgard, John Flynn, and Olivier Rieppel—helped to elevate the profile of the department and the Field Museum to scientific prominence both nationally and internationally. As one colleague wrote, “Whatever success the department enjoyed during the 1980s, 1990s and on up to the present day, can all be traced back to John and the key decisions that he made.” This type of contribution to the scientific enterprise is hugely impactful yet underappreciated. We will all miss his presence.
This note was written by John's colleagues. A memorial event is being planned.