Adolf "Dolf" Seilacher (24 February 1925 – 26 April 2014) was a German palaeontologist. He worked in evolutionary and ecological palaeobiology for over 60 years. He is best known for his contributions to the study of trace fossils; constructional morphology and structuralism; 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. He earned his doctorate in 1951, focusing on trace fossils. Seilacher later moved to the University of Frankfurt in 1957 and then to the University of Baghdad before being appointed to a position in paleontology at Göttingen. He returned to Tübingen in 1964 as Schindewolf’s successor. After 1987, he held an Adjunct Professorship at Yale University.

Significant work

Seilacher has written over 200 publications on many different subjects. His most famous work involves studying trace fossils, which are marks left by ancient organisms. In 1967, he wrote about how the depth of water affects these fossils. He introduced the idea of ichnofacies, which are groups of trace fossils that depend mostly on water depth. Later, he expanded this idea to include other factors like the type of surface, oxygen levels, and salt content. He also studied trace fossils to understand the behaviors of ancient organisms, including early computer models of their shapes, which he developed with David Raup in 1969. Much of this research is summarized in a book titled Trace Fossil Analysis (2007).

In 1970, Seilacher started a program called "Konstruktions-Morphologie," which focused on three factors that shape organisms: their environment and how they adapt, their evolutionary history, and the physical structure of their bodies. He argued that history and physical construction set limits on how organisms can change over time. This idea influenced later scientists like Stephen Jay Gould and Richard Lewontin, who wrote about how not all features in evolution are the result of direct adaptation.

Seilacher was interested in how patterns form in nature. He supported models that explain how certain structures, like pneu structures, develop naturally. These are fluid-filled shapes that form because of the need to spread pressure evenly. Because of this focus on structure, Seilacher is often seen as a structuralist.

He 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 system to classify these layers, which became widely accepted. Much of his work has focused on how fossils are preserved and the study of taphonomy, which is the process of how organisms become fossils.

Seilacher's most controversial work involved the Ediacaran assemblages, a group of ancient fossils. He and Friedrich Pflüger suggested in 1994 that these fossils were pneu structures and not related to modern animals. This view has been debated, as the relationships of these organisms remain unclear. He also believed many of these fossils were giant xenophyophores, a type of large single-celled organism. He appeared in a film called Volcanoes of the Deep Sea and took a dive on the DSV Alvin to study modern examples of the trace fossil Paleodictyon.