Adolf "Dolf" Seilacher (24 February 1925 – 26 April 2014) was a German scientist who studied ancient life for more than 60 years. His work focused on how ancient life changed and interacted with its environment over time. He is most famous for his research on trace fossils; how organisms' bodies are built and their structures; biostratinomy, Lagerstätten, and the Ediacaran biota.
Career
Seilacher earned his doctorate under Otto Heinrich Schindewolf at the University of Tübingen. He was also influenced by local paleontologist Otto Linck. He served in World War II and continued his studies at Tübingen, communicating with the French ichnologist Jacques Lessertisseur. In 1951, he received his doctorate on trace fossils. He later moved to the University of Frankfurt in 1957 and then to the University of Baghdad before accepting a position in paleontology at Göttingen. He returned to Tübingen in 1964 as the successor to Schindewolf. After 1987, he held an Adjunct Professor position at Yale University.
Significant work
Seilacher has written more than 200 scientific papers on many different topics. His most well-known work involves trace fossils, which are marks left by ancient organisms. In 1967, he introduced the idea of ichnofacies, which are groups of trace fossils that are mainly influenced by the depth of the environment where they formed. Later, he expanded this idea to include other factors like the type of material in the environment, oxygen levels, and salt content. He also studied trace fossils to understand the behaviors of ancient organisms, leading to early computer models of their shapes, which he developed with David Raup in 1969. Much of his research on trace fossils is collected in a book titled Trace Fossil Analysis (2007).
In 1970, Seilacher introduced a program called "Konstruktions-Morphologie," which focused on three main factors that influence the shapes of organisms: their relationship to their environment, their evolutionary history, and the structural principles that guide their development. He argued that evolutionary history and structural rules set limits on how organisms can change over time. This idea influenced scientists like Stephen Jay Gould and Richard Lewontin, who later wrote about how not all features in evolution are perfectly adapted.
Seilacher was interested in how patterns form in nature. He supported models that explain the development of certain structures through self-organization, such as pneu structures, which are fluid-filled shapes that form due to tension spreading across their surfaces. Because of this focus on structure, he is often considered a structuralist.
Seilacher created the term Lagerstätten, which refers to special rock layers that contain unusually well-preserved or numerous fossils. In a 1985 paper, he proposed a classification system for these layers that became widely used. Much of his research also focused on how fossils are preserved in rocks, a field called taphonomy.
His most debated work involved the Ediacaran assemblages, a group of ancient fossils. In 1994, he and Friedrich Pflüger suggested these fossils were pneu structures and not related to modern animals. Many scientists disagreed with this view, but some supported it because the relationships of these ancient organisms remain unclear. Seilacher also believed many of these fossils were large single-celled organisms called xenophyophores. He participated in a documentary called Volcanoes of the Deep Sea, where he dove in the DSV Alvin to study modern examples of the trace fossil Paleodictyon.