Curious Mind: A Celebration of the Extraordinary Life and Ichnological Contributions of Adolf “Dolf” Seilacher (1925–2014)

Introduction

Curiosity (from the Latin curiosus “careful, diligent, curious,” akin to cura “care”) is a quality related to inquisitive thinking such as exploration, investigation, and learning, evident by observation in human and many animal species. The term can also be used to denote the behavior itself, being caused by the emotion of curiosity. As this emotion represents a thirst for knowledge, curiosity constitutes a major driving force behind scientific research and other disciplines of human study. Dolf Seilacher (Fig. 1A) personified this definition, and his extraordinary life stands a testament to all of us on how science should be undertaken. Although we are concentrating on Dolf's ichnological contributions, his research dealt with many other aspects of paleontology. Dolf's ichnological contributions included work in constructional morphodynamics, the study of exceptionally preserved fossil deposits (Lagerstätten), and Ediacaran assemblages, where he is known for proposing the innovative hypothesis of the Vendobionta. In each of these fields, Dolf's creative work stimulated further research, which led to fundamental discoveries and imaginative interpretations. His research is really based on first principles and the power of observation. It is rare when a discipline can chart its inception to a single practitioner, but ichnology owes its modern foundation to Adolf “Dolf” Seilacher and a series of papers that he published from 1953 to 1964. In these papers, Dolf gave life to the field of ichnology—until then, a somewhat anecdotal science that was considered by most paleontologists as a quaint field inhabited by the flotsam of paleontology. Dolf really showed us the beauty of the science and the significance of understanding animal-sediment inter-relationships.

Figure 1. A. Adolf “Dolf” Seilacher (February 24, 1925–April 26, 2014), B. A young Dolf Seilacher in the field with Bernard Hauff and Walter Häntzschel (middle) (photograph courtesy of Edith Seilacher). C. Otto Heinrich Schindewolf (June 7, 1896–June 10, 1971), Dolf's supervisor at the University of Tübingen. D. Dolf and Frank Westphal (the vertebrate paleontologist at Tübingen) with Otto Schindewolf planting a gingko tree on the occasion of Schindewolf's 68^th birthday (photograph courtesy of Edith Seilacher).

Building on the work of earlier geologists such as the German palaeontologist Rudolf Richter, founder of the Senckenberg Laboratory in Wilhelmshaven, and the Austrian paleontologist Othenio Abel, Dolf was able to put order into the fledging science. Since the inception of the Senckenberg Laboratory (Pemberton, 2003; Cadée and Goldring, 2007), Germany had become the center of innovation in animal-sediment relations, taphonomy, and Aktuo-paläontologie (Actualistic Paleontology).

One of us (SGP) first became aware of Dolf in 1971, while doing his BSc thesis at Queen's University, Kingston, Ontario, on the Ordovician Gull River Limestone. This unit contained trace fossils, and SGP started reading about them. He found Dolf's seminal papers, but they were written in German, and so it took him sometime to translate them all. The more SGP read, the more he was hooked, and he decided that ichnology was what he wanted to do. He first met Dolf at McMaster University, Hamilton, Ontario, in 1976, where he was doing his PhD. Dolf had been invited to give a series of talks by McMaster paleontologist Gerd Westermann (a classmate of Dolf's at the University of Tübingen). The talks were eagerly anticipated, but the senior author was mystified that Dolf did not even mention trace fossils; the talks centered on cephalopod suture strength. He soon learned that the hallmark of Dolf's science was to never expect the obvious!

Adolf “Dolf” Seilacher (February 24, 1925–April 26, 2014)

Recent obituaries on Dolf Seilacher have been written by Briggs (2014) and Fortey (2014). Details on Dolf's life come from his Curriculum Vitae, kindly supplied by his widow Dr. Edith Seilacher and from the acknowledgements in his landmark trace fossil book Trace Fossil Analysis (Seilacher, 2007a).

Adolf “Dolf” Seilacher was born on February 24, 1925, in Stuttgart, Germany, the son of Adolf Seilacher, pharmacist, and Frida Seilacher-Pfizer from Gaildorf. During his formative high school years (Fig. 1B), Dolf was influenced by two tutors: a local physician Dr. R. Stierlin, and the paleontologist Dr. Otto Linck. Linck was well aware of ichnology and published a number of papers on the subject (Linck, 1942, 1943, 1949a, 1949b, 1954, 1956, 1961). Dolf started his publishing career early with a paper on fossil sharks (Seilacher, 1943). At the age of 18, Dolf served his country in World War II as part of the German Navy from 1943 until 1945. During a visit to Canada in 1996, Dolf and his wife Edith stayed with George Pemberton and during a reception held at his home, Dolf and George Pemberton's father (a veteran of the British Navy and almost exactly the same age as Dolf) discovered that they may have faced one another in a naval conflict. It was touching when they toasted one another for having both survived the war.

After the war, Dolf attended the University of Tübingen, Germany working under the tutelage of the brilliant paleontologist Professor Otto Schindewolf (Fig. 1C) from 1945–1951. He received his Ph.D. in 1951 after completing a thesis on Mesozoic trace fossils. This brought him into contact with the Senckenberg Institute in Wilhelmshaven, where he was introduced to Prof. Wilhelm Schäfer and actuo-paleontology, and Prof. Walter Häntzschel, who then was compiling the Treatise on Paleontology (Part W) volume on Trace Fossils and Problematica (Häntzschel, 1962, 1965, 1975). He also completed a Habilitation in 1957, with a thesis on Spinctozoan sponges (Seilacher, 1962b).

Upon completion of his PhD, Dolf had the privilege of joining Prof. Schindewolf on his expedition to the Salt Range of Pakistan. Although their original target had been the end-Permian mass extinction, this trip introduced Dolf to Cambrian shallow-marine ichnocoenoses, in which the various activities of trilobites played a dominant role. The results were published in Seilacher (1955a and b). Later field work in Spain, led to the scheme of Cruziana ichnostratigraphy which was a dominate research theme that Dolf explored in the 1970s. Ichnostratigraphy was further refined in the symposia of the National Oil Company of Libya organized by Mustapha Salem, trips to Jordan arranged by Friedrich Bender, and to Saudi Arabia with Muhittin Senalp.

Equally important was a first trip to Italy, where the rich university collections in Pisa and Florence made Dolf familiar with the flysch ichnocoenoses and with the new ideas of Prof. Caesar I. Migliorini about sand being imported into deep-sea basins. Later, the recognition of the Nereites Ichnofacies lent strong support to Migliorini's and Phillip H. Kuenen's turbidite theory, as well as to the new paradigm of plate tectonics.

In the United States, Dolf's work captured the interest of oil companies, which were more concerned with the significance of the facies relationships of trace fossils. Consulting for Jersey Research Company (now Exxon Production Research Co.) in 1962 by the initiative of Charles Campbell gave Dolf a chance to study a broad range of ichnocoenoses throughout the southwestern United States. The confidential report that Dolf wrote for Jersey Research Company took on a near mythical status among ichnologists and was often talked about but never seen. These early trips set the stage for much of Dolf's subsequent ichnological research.

Dolf held teaching positions in the following universities; 1951–1957, assistant professor, University of Tübingen; 1957–1959, docent, University of Frankfurt/Main; 1961–1964, professor, University of Göttingen; 1964–1990, professor, University of Tübingen; and 1987–2010, professor (adjunct), Yale University. Of special note was his being named the successor of his mentor Schindewolf when he retired in 1964 (Fig. 1D). This enabled the University of Tübingen to remain the center of paleontological research in Germany.

Dolf also served as a visiting scientist at a large number of institutions worldwide (summarized in Table 1). These appointments afforded Dolf the opportunity to visit and study many famous geological sites (Fig. 2) and enabled him to apply his keen sense of observation and imaginative interpretations to a diverse array of subjects.

Table 1. List of visiting professor appoints held by Dolf Seilacher.

Year	Rank	Institution
1960–1961	Assistant Professor	University of Baghdad, Iraq
1963–1964	Visiting Lecturer	Johns Hopkins University, Baltimore
1968	Visiting Professor	University of California, Santa Cruz
1972	Visiting Professor	Moscow University
1973	Visiting Professor	Consejo Nacional de Investigaciones, Científicas, Argentina
1979	Visiting Professor	University of Mosul, Iraq
1979	Distinguished Professor	University of Kansas, Lawrence, Kansas
1979	Visiting Professor	University of Malaya, Kuala Lumpur, Malaysia
1982	German National Fellow	New Zealand Universities
1984	Visiting Professor	Yarmouk University, Irbid, Jordan 1984 Visiting Professor Jiaozuo Mining College, Jiaozuo, Henan, China
1986	Visiting Professor	Wuhan College of Geology, Beijing, China
1986–1987	Visiting Professor	University of Benin, Cotonou, Benin
1987	Professor of Zoology	University of Washington, Friday Harbour Laboratories Washington
1989	Visiting Professor	Argentinean Paleontological Association, Buenos Aires, Argentina
1992	Visiting Professor	Kyoto University, Japan
1994	Visiting Professor	University of Valencia, Spain
1995	Visiting Professor	Natural History Museum, Chiba, Japan
1996	Visiting Lecturer	University of Alberta, Edmonton, Canada
1998	Professor of Zoology	University of Washington, Friday Harbour Laboratories (mollusk course with A. Cohn and M. LaBarbera)
2001	Erskine Fellowship	Canterbury University, Christchurch New Zealand

Figure 2. A. Dolf with Don Hattin of Indiana University (Bob Frey's thesis supervisor) in the field, circa 1978. B. Dolf with Rod Tillman (standing) and Chuck Seimers (sitting) in the field during a SEPM Field trip to the Book Cliffs in 1978; C. Dolf and others at probably the first ichnology field trip, 1971 in central Texas, from left to right: 5 graduate students at Rice at the time: Eric McHuron, Martin Schuepbach, John McCrevey, Ken McMillan, Mike Brady; Kent Chamberlain just behind Stan Bues; Leo Laporte in back, Steve Alpert in front; unknown hidden behind Steve; Cortez Hoskins big guy in back (Unocal Research), Bill Fischer in front next to Dolf, unknown partially hidden behind Bill, Chuck Campbell with face hidden, Dolf, Bob Perkins with red jacket, unknown, unkown and Bill Meyers Rice grad student. Photo taken by John Warme. (photo courtesy of John Warme); D. Mid-1970s field trip to the Ouachitas Mountains in Oklahoma, organized with symposium by Paul Basan, Amoco. Dolf on turbidites (photo courtesy of John Warme).

Following Dolf's retirement from the University of Tübingen in 1990, he spent one semester a year as an adjunct professor at Yale University in New Haven, Connecticut (USA), until 2009. He had initiated his involvement with Yale in 1987. There he concentrated on his then scientific goal, a book on the morphodynamics of invertebrate skeletons, in which major groups were being discussed in terms of constructional morphology, evolution, and taphonomy (Seilacher and Gishlick, 2014). This required much studying and drawing of actual specimens, for which the well-ordered fossil collection of the Peabody Museum provided a wonderful resource.

On a personal level, Dolf was married in 1957 to fellow paleontologist Dr. Edith Drexler. Edith was a devoted partner and in later years traveled extensively with Dolf and contributed in many ways to Dolf's innovative research (Fig. 3). Dolf and Edith have two children: daughter Ulrike, born in 1958, and son Peter, born in 1963, as well as three grandchildren.

Figure 3. Dolf and his wife Edith, A. Dancing in 2010, B. Formal attire, C. In the field in Jordan, 2000 doing the peel “Waves of Petra” for Fossil Art, and D. With guides in Jordan, 2000. (Photographs courtesy of A. Ulrike Seilacher, B. Susam Butts, C. and D. Freidrich Pflüger).

Dolf's pioneering research garnered him accolades the world over, including 1980 Fellowship in the American Association for the Advancement of Science; the 1983 R. C. Moore Medal of the Society of Economic Paleontologists and Mineralogists; 1984 Honorary Professor, Jiaozuo Mining College, Jiaozuo, Henan, China; 1987 Mitglied der Akademie der Wissenschaften Heidelberg; 1988 Corresponding Member of Akademie der Wissenschaften, Göttingen; 1989 Honorary Member of the Geological Society of London; 1990 Advisory Board, Academia Sinica, Paleobiology Section, Nanjing, China; the 1992 Crafoord Prize of the Royal Swedish Academy of Sciences; 1993 Honorary Member of the Royal Physiographic Society of Lund; 1993 Verdienstmedaille des Landes Baden-Württemberg; the 1993 Paleontological Society Medal, USA; the 1994 Steinmann Medal of the Geologische Vereinigung; 1994 Honorary Member, Paläontologische Gesellschaft; 1994 Honorary Member, der Gesellschaft für Naturkunde in Württemberg; 2000 Honorary Member European Palaeontological Union; a special award from ichnologists presented to Dolf at the First International Congress on Ichnology at Trelew, Argentina in 2004; the 2006 Lapworth Medal of the English Palaeontological Society London; and the 2013 Otto Jaeckel Medal of the Paläontologische Gesellschaft.

Of particular note is the 1992 Crafoord Prize (Fig. 4A) in astronomy and mathematics, biosciences, geosciences, or polyarthritis research. The Crafoord Prize is awarded annually by the Royal Swedish Academy of Sciences and is presented by the King of Sweden (Fig. 4B) according to a rotating scheme. These disciplines are chosen so as to complement those for which the Nobel Prizes are awarded. The recipients are worthy scientists who receive the prize in accordance with a set scheme:

• Year 1 Astronomy and Mathematics

• Year 2 Geosciences

• Year 3 Biosciences

• Year 4 Astronomy and Mathematics

Figure 4. A. The Craaford Prize medal front, awarded to Dolf in 1992; and B. Dolf receiving the Craaford prize from King of Sweden (photograph courtesy of Edith Seilacher).

The prize in polyarthritis is awarded only when a special committee has shown that scientific progress in this field has justified such an award. The prize sum of SEK 4 million (approximately US$600,000) makes the Crafoord one of the world´s largest scientific prizes.

The citation for the award reads:

Adolf Seilacher belongs to the great founders of schools of method and thinking in the geosciences. He was a student of O. H. Schindewolf´s, who dominated European evolutionary paleontology about the middle of the century. Adolf Seilacher´s research aimed from the beginning at understanding the interplay of extinct organisms and their life environment. This research led to breakthroughs in understanding the evolution of life and has developed a flexible and sophisticated methodology.

Seilacher investigates imprints that organisms made as traces of life activities in the geological environment and by interpreting them reconstructed the environment. He also investigated the influence of geological evolution on the life environments, thereby mapping out essential conditions for the evolution. He found among other things similar behavioral and constructional adaptations in animals belonging to different evolutionary lineages. He finds requirements posed by the environment to be met by the specific constructional details and developed methods to characterize these constructions and derive the requirements, which they met.

Fossils are often poorly preserved, but Seilacher found new and meaningful information by studying the causes and processes of their degradation. The over 600 million year of Ediacara Fauna found in Australia was subjected to his special scrutiny; it turned out to consist, among other things, of a surprising array of traces made by organisms and remains of organisms that cannot be placed in living categories like animals and plants.

Seilacher has broken new ground in different branches of paleontology. His holistic approach to the biosphere and environment, as well as his precise and, where possible, rigorous methods have greatly influenced research on evolution all over the world. He has numerous students and followers in different countries that are successfully employing his approach and methods. Retrieved from http://www.crafoordprize.se/press/arkivpressreleases/thecrafoordprize1992.5.32d4db7210df50fec2d800017997.html

Dolf held a number of administrative and editorial positions. On several occasions since 1964, he served as the Head of the Geology Department of the University of Tübingen. Additionally, he served as the dean of science, University of Tübingen, from 1969 to 1970 and was president of the Paläontologische Gesellschaft from 1977 to 1979. From an editorial point of view, Dolf was the editor of Zentralblatt für Geologie und Paläontologie, Abt. II: Paläontologie from 1970 to 1984. He served as the editor of Neues Jahrbuch für Geologie und Paläontologie, Abt. Paläontologie from 1969 to 1997, and he was Associate Editor of Ichnos from 1992 to 2014. Dolf also was the Speaker of the Sonderforschungsbereich, 53,“Palökologie” from 1970 to 1984, and was Member, Sonderforschungsbereich 230. “Natürliche Konstruktionen,” Stuttgart from 1984 to 1994. Dolf also served as adjunct curator of invertebrate fossils, Peabody Museum, Yale University, from 1987–2010.

Seilacher's philosophy for science was succinctly summed up by Dolf himself in his 1994 acceptance speech for the Paleontology Society Medal, in what he termed his 10 commandments (Seilacher, 1994, pp. 917–918):

1. The analytical power of the human eye, which can only be aided, but not substituted, by instrumentation.

2. The unity of description and interpretation, because observation is a self-correcting dialogue with the object.

3. The value of self-drawn illustrations for the observational process, as well as for the communication of the results.

4. The unity of research and teaching, which broadens our view and confronts us with ever new generations of fresh minds.

5. The heuristic value of free and interdisciplinary discussion – not to win, but to test and improve our own ideas.

6. International cooperation to broaden our database and to take advantage of different cultural traditions.

7. Popularization of our insights in talks, media, and museum exhibits, because paleontology can offer the public more than only dinosaurs.

8. Paleontologists who stand on two legs by thinking simultaneously in geobiological and in paleobiological frame-works.

9. The justification of unconventional and even provocative modeling, because this keeps our science going.

10. The joy of doing paleontology.

Dolf also was responsible for coining the phrase “to be Dolfed.” At scientific meetings, Dolf had the ability to ask the perfect question, the one that most presenters did not want to be asked. His keen observations and probing questions challenged interpretations and would force the investigator to defend his or her interpretations based on sound observations. Many ichnologists have been Dolfed (Fig. 5), and most of them were proud of it because in the end their work was the better for it.

Figure 5. Christian Meyer being “Dolfed” at a cathedral during the 5th International Lithographic Limestone Meeting in Switzerland (photograph taken by Daniel Marty, supplied courtesy of Christian Meyer).

Dolf was also a movie star, stealing the show in the feature film Volcanoes of the Deep Sea, a 2003 IMAX film executively produced by James Cameron (Avatar) and directed by Stephen Low (Titanica) with narration from actor Ed Harris (Fig. 6A). The film opens with Dolf at the Zumaya Flysch in Spain (Fig. 6B), saying: “I came here for the first time 50 years ago, on my honeymoon. It was certainly not my intention to be unfaithful, but here on these cliffs I fell under the spell of a mistress, one that has not released her grip in all these years.” The mistress was in fact the ichnofossil Paleodictyon nodosum (Fig. 6C), a hexagon-shaped biogenic structure that had puzzled ichnologists for a long time. In a landmark paper (Seilacher, 1977b), Dolf concluded that the producer of the trace fossil used the morphology of the burrow system to farm microbes. The film follows Dolf and paleontologist Peter Rona aboard the research vessel Atlantis (Fig. 6D), setting out on a quest to find the elusive Paleodictyon nodosum producer. Dolf and Peter go down in the deep-sea submersible Alvin, looking for the organism responsible for creating Paleodictyon by taking samples from the ocean floor near black smokers and lava vents. The robot arm of the submersible Alvin directed a hose that squirted water at a hexagonal array of holes, slowly removing layers of mud. The delicate operation quickly revealed a hexagonal array of subsurface tunnels identical to those of the fossil. The results of the expedition were reported in Rona et al. (2009). Unfortunately, the organism proved to be elusive, and at the end of the movie Dolf still had not found the trace-making organism. He remarked, “My wife would probably be happy that I never found my mistress of the seas.” And on that somewhat wistful note, the movie ends.

Figure 6. Dolf the movie star. A. The DVD cover for the movie “Volcanoes of the Deep”, B. Dolf doing field work at the Zumaya Flysch in Spain, C. Paleodictyon nodosum, D. Dolf and Peter Rona aboard the research vessel Atlantis.

Dolf passed away at his home in Tübingen on Saturday, April 26, 2014, at the age of 89. The funeral ceremony was held on Tuesday afternoon, May 6, in the Martins church in Tübingen, Frischlinstrasse 33. Dolf's ashes were placed with the grave of his pre-pre-predecessor at the University of Tübingen, Professor Ernst Koken.

Ichnological contributions

Basic ichnological principles

Osgood (1975) attempted to subdivide the history of ichnology on the basis of periods of time with relatively stable characteristics. This scheme has recently been modified to include two additional ages (Baucon, 2010; Pemberton et al., 2011; Baucon et al., 2012).

1. Age of Naturalists (Pre-1823): This age spanned roughly the 15th to 17th centuries during which several Renaissance intellectuals depicted and studied trace fossils, although ichnology existed as disconnected ideas about traces.

2. Age of Fucoids (1823–1881): This age started with Brongniart (1823), who considered invertebrate trace fossils as fucoids, or seaweed. During this historical stage, the botanical interpretation dominated the scientific view of trace fossils.

3. Period of Reaction (or Age of Controversy) (1881–1925): based on analogies with modern traces, Nathorst (1881) argued that many fucoids were trace fossils generated by the activity of animals. This aroused a consistent debate, with prominent scientists like Lebesconte and de Saporta supporting the botanical interpretation.

4. Development of the Modern Approach (1925–1953): This stage started with the establishment of the Senckenberg Laboratory, a marine institute devoted to neoichnology (Pemberton, 2003; Cadée and Goldring, 2007). The geologists of the period agreed with a zoological origin of trace fossils, opening the avenues to the decisive steps toward modern ichnology.

5. Modern Era of Ichnology (1953 to the present day): This period saw the foundation of the central concepts of modern ichnology, starting with Seilacher's (1953a,b) seminal publications on the methods of ichnology.

The Modern Era of ichnology is defined by the appearance of the landmark series of papers published by Dolf in the 1950s and 1960s. These papers outlined many of the basic tenets of modern ichnology, including the ethological classification of biogenic structures (Seilacher, 1953a, 1953b), the toponomic classification of biogenic sedimentary structures (Seilacher, 1953a), and the development of the ichnofacies concept (Seilacher, 1958, 1963a, 1964a, 1967c, 1967d). These papers were summarized in a chapter of the book Approaches to Paleoecology (Seilacher, 1964a). This publication, along with the response to his highly influential paper in a theme volume dedicated to discerning paleobathymetry (Seilacher, 1967d), soon led to trace fossils within the “Seilacherian” ichnofacies framework being regarded (albeit erroneously) as paleobathymeters. These papers, however, were instrumental in making ichnology a legitimate aspect of paleontology, sedimentology, and stratigraphy.

Seilacher's overarching philosophy was that trace fossils represent in situ animal behavior and, in many cases, broad epifaunal and infaunal communities that were sensitive to physico-chemical conditions imparted by the sedimentary environment. Seilacher's models and interpretations are still widely employed today, and they provided the momentum to propel ichnology into the Modern Era.

Ichnofacies

If one were forced to choose the most influential aspect of Seilacher's great body of work, it would be difficult not to settle on Dolf's massively influential ichnofacies framework. Seilacher's recognized that suites of trace fossils united by ethological ties are recurrent in the fossil record, and trace fossils could only be applied as crude biostratigraphical entities. The original Seilacherian ichnofacies express temporally and geographically recurring ethological groupings of trace fossils (Seilacher, 1962a, 1978). The concept proved so useful that Dolf's original ichnofacies have been retained in some shape or form by almost all subsequent workers (cf., summaries provided in Ekdale et al., 1984; Frey et al., 1990; Buatois and Mángano, 1995, 2011; MacEachern et al., 2007a, 2010). Dolf evolved the concept of ichnofacies throughout the 1950s, and the first application of his construct was to associate ichnofacies to depositional depth. This effort contributed to a volume of work that was aimed at establishing different means of assessing bathymetry in the rock record. Through the 1960s, Seilacher expanded the ichnofacies concept and explored its application. By the 1980s, acceptance of the ichnofacies paradigm was pervasive in the field of ichnology. Today, whether one applies ichnofacies or the later developed ichnofabric analysis, all workers are familiar with the common “Seilacherian” ichnofacies.

Today, 14 archetypal ichnofacies that recur temporally and spatially have been defined: Scoyenia, Mermia, Coprinisphaera, Celliforma, Termitichnus, Octopodichnus-Entradichnus, Trypanites, Teredolites, Glossifungites, Psilonichnus, Skolithos, Cruziana, Zoophycos, and Nereites (see Seilacher, 1967c, and references therein; Bromley, 1972; Bromley et al., 1984; Pemberton and Frey, 1985; Frey and Pemberton, 1987; Buatois and Mángano, 1995, 2011; de Gibert et al., 1998; Genise et al., 2000). In marine strata, ichnofacies analysis is a broadly accepted tool used for rapid and reliable determination of sedimentary conditions. Departures from the archetypal ichnofacies are used to further refine sedimentary interpretations of parameters, such as fluctuations and reductions in salinity and dissolved oxygen, as well as variability in sedimentation rates (e.g., Pemberton et al., 1982; Savrda and Bottjer, 1987; Pemberton and Wightman, 1992; MacEachern et al., 2005, 2007b; MacEachern and Gingras, 2007). Furthermore, the occurrence of substrate-controlled ichnofacies is used to identify stratigraphic discontinuities and helps to constrain sequence stratigraphic interpretations (e.g., Vossler and Pemberton, 1988; MacEachern et al., 1992; MacEachern and Burton, 2000; Pemberton and MacEachern, 2005; MacEachern et al., 2014). Recent years have witnessed progress in further expansions of the ichnofacies concept in continental settings (e.g., Buatois and Mángano, 1995, 2011; Genise et al., 2000, 2010).

Evolution of trace fossil communities

Stephen Jay Gould (1987) discussed the tension between time's arrow and time's cycle in our understanding of the Earth's history. This tension is certainly evident in Seilacher's work. Whereas the ichnofacies model emphasizes a cyclical idea of time, with trace-fossil suites recurring through long intervals of geologic time as a response to a given set of environmental conditions, Dolf understood at the same time the potential of trace fossils to illuminate macroevolutionary issues, such as the evolution of behavior, emphasizing the directional component of geologic time (Mángano and Buatois, 2012). During the 1960s, he started to think along these lines, making brief comments in papers of a more general nature (e.g., Seilacher, 1967d). Later, he published a classic paper on the evolution of deep-sea trace fossils (Seilacher, 1974a), in which he plotted ichnodiversity changes through the Phanerozoic, and illustrated evolutionary optimization for Nereites, Oldhamia, Zoophycos, and Dictyodora. This was followed by a more comprehensive paper in which he evaluated further the topic of deep-marine trace fossil evolution, as well as that of shallow-marine (including intertidal) ichnofaunas, expanding on the more theoretical aspects of macroevolution (Seilacher, 1977a). During the next years, he pursued this avenue of research by making adjustments and additions to the model (e.g., the evolution of echinoid trace fossils in Seilacher, 1979b and the evolution of Zoophycos in Seilacher, 1986).

One of the most impressive aspects of his model of the evolution of deep-sea trace fossils is that he personally visited each of the localities plotted in his ichnodiversity diagrams, allowing him to have a direct insight into these ichnofaunas. This is so unusual for this type of study that it has drawn the attention of many paleobiologists who work with large databases, most notably the late Jack Sepkoski (see Sepkoski, 1994).

Ediacaran paleobiology and the cambrian “Explosion”

Seilacher's macroevolutionary interests were also illustrated by his contributions to another field in which he has undoubtedly left an enormous mark: Ediacaran paleobiology. In the mid-1980s and 1990s, he published a dramatic re-interpretation of the Ediacaran biota (Seilacher, 1984d, 1985c, 1989a, 1992a; Buss and Seilacher, 1994). The traditional view of Ediacaran organisms emphasized supposed similarities with modern groups, implying evolutionary continuity across the Ediacaran-Cambrian transition. In this light, Ediacaran iconic fossils, such as Dickinsonia, Pteridinium, or Rangea to name just a few, were interpreted as soft-bodied ancestors of modern metazoans. After restudying specimens from some of the classic localities (e.g., southern Australia, Namibia, Newfoundland, White Sea), Seilacher noted that similarities with modern forms were actually superficial and that the common trait among Ediacaran organisms was their quilted structure. Based on this, Seilacher concluded that the Ediacaran biota was a distinct evolutionary episode rather than a nonskeletal start of Phanerozoic-style metazoan life. In other words, instead of being precursors of later biotas, Ediacaran creatures formed a unique and extinct kingdom that Dolf named Vendobionta. Later, he adjusted his interpretation by considering them giant protozooans that he correspondingly placed within the animal kingdom as an extinct order or subclass of rhizopods (Seilacher et al., 2003; Seilacher, 2007a). The view of the Ediacaran biota as a failed experiment was praised by Gould (1984) in an article in Natural History, where he told of his experience listening to Dolf as he presented this idea at a GSA annual meeting. Some of Gould's reflections are worth citing, for example: “Dolf is the greatest observer I have ever had the privilege of knowing. He looks at common objects, scrutinized by generations of researchers, and invariably sees something new and unexpected” (Gould, 1984, p. 14).

Interestingly, by showing that the Ediacaran biota does not represent the roots of the metazooan tree of life, Dolf underscored the importance of ichnologic data in macroevolution because he noted that trace fossils in fact record the presence of worm-like animals in Precambrian rocks, therefore showing the existence of these Phanerozoic-type animals in Ediacaran rocks. However, parallel to this, Dolf demonstrated that many supposed Ediacaran ichnotaxa were not actually trace fossils, shrinking the total number of Ediacaran ichnotaxa (Seilacher et al., 2005). Also, he showed that Ediacaran biotas developed in direct association with resistant matgrounds, thereby representing actualistic ecosystems. By the early Cambrian, matgrounds became rare due to the onset of bioturbation and were replaced by mixgrounds; this evolutionary event was referred to as the “Agronomic Revolution” (Seilacher and Pflüger, 1994; Seilacher, 1999c). By emphasizing the taphonomic importance of microbial films, Dolf solved a long-standing puzzle, that is, the unusual preservation of delicate, soft-bodied organisms in well-oxygenated, coarse-grained sandstones. His ideas on Ediacaran paleobiology changed our view of one of the most critical times in the history of the biosphere.

Cruziana stratigraphy

Because trace fossils are typically characterized by long temporal ranges and narrow facies ranges, they are extremely useful in paleoenvironmental analysis and less so in biostratigraphic studies. However, Dolf Seilacher understood that if some biogenic structures can preserve specific fingerprints of their producers and if the producers record significant evolution, then the trace fossils may also yield biostratigraphic implications (see discussion in Buatois and Mángano, 2011).

Although he has explored these issues with a relatively wide variety of trace fossils, his classic model is based on trilobite trace fossils, known as Cruziana stratigraphy. This ichnostratigraphic scheme was initially developed in the nineteen-seventies (Seilacher, 1970b), based on rocks containing Cruziana and Rusophycus (and to a lesser extent Dimorphichnus). Nonetheless, as with other topics, Dolf continued to explore these issues until virtually the time of his death (Seilacher, 1992k, 1983b, 1996c, 2007a; Seilacher and Alidou, 1983; Fortey and Seilacher, 1997; Seilacher et al., 2002, 2003). He amassed a huge amount of information, having seen trilobite trace fossils in a large number of Paleozoic deposits (typically Cambrian-Ordovician but younger rocks as well) in Wales, Sweden, Spain, Poland, Canada, United States, Argentina, Jordan, Saudi Arabia, Iraq Egypt, Libya, Benin, and Chad, among other places.

This scheme was developed for Gondwana for the most part, based on the recognition of more than 30 ichnospecies of Cruziana (and Rusophycus) believed to display biostratigraphic significance (Seilacher, 1970b, 1992k). The stratigraphic ranges of these ichnospecies comprise between one and three series, although the majority of these ichnotaxa are restricted to only one or two series. By far the most extensive dataset comes from the Furongian to Middle Ordovician interval, but subsequent improvements have been produced for the Lower Silurian (Llandovery) (Seilacher, 1996c). This biostratigraphic scheme has been used to date otherwise unfossiliferous rocks, having been applied quite successfully in Lower Paleozoic reservoir rocks of northern Africa (Seilacher et al., 2002).

Event stratigraphy

In two seminal papers, Seilacher (1981a, 1982e) recognized that episodic sedimentation events, including turbidites, tempestites, inundites, and phytodetrital pulses, have a number of common characteristics. For example, episodic sedimentation comprises three stages, including the onset, culmination, and waning of water turbulence associated with the event, with these hydraulic thresholds accompanied by distinctive erosional and depositional structures. Seilacher also recognized that episodic sedimentation events redistribute organic and inorganic sedimentary material along vertical and horizontal gradients. It was recognized that the living conditions for benthic organisms could be altered as a result of the changed consistency of the substrate and the food content/distribution of the bottom sediments. This theme has been explored by subsequent researchers (e.g., Pemberton and Frey, 1984; MacEachern and Pemberton, 1992; Pemberton et al., 1992; Savrda and Nanson, 2003), and the recognition of preevent and postevent trace fossil assemblages is taken into account in all dynamic sedimentary environments.

Interestingly, Dolf's vision regarding event stratigraphy has yet to come to fruition. In 1981a, he deduced that “in response [to sedimentation events], corresponding background and post-event communities expand and contract alternatively, but in different proportions. Therefore, the two communities might be expected to differ in the tempo and mode of evolution. Storm beds in epeiric seas, benthic horizons in bituminous shales and trace fossils in turbidite sequences are cited as potential test areas” (Seilacher, 1981a, p. 39), thereby suggesting that opportunistic and ambient colonizers may well evolve at different rates owing to their temporally unequal access to ecospace. This is a tantalizing hypothesis that has yet to be fully explored. However, like many ideas Dolf developed, this one will likely continue to move forward as the ichnological muse of subsequent generations.

Constructional Morphology

In the late 1960s and into the 1980s, Dolf Seilacher explored the second field of study that he founded, constructional morphology. Dolf's vision was articulated in one of his early papers on the topic: “Any biogenic form can be understood on the basis of three major causes: a traditional, a functional and a fabricational cause. This triple approach, called constructional morphology, can be equally applied to the shapes of organisms or their parts, to animal products such as spider webs or burrow systems, or to human artefacts” (Seilacher, 1973b, p. 451). In a subsequent study, Seilacher (1991a) expanded this ternary diagram to a tetrahedron by adding a fourth dimension, “effective environment,” in an attempt to incorporate facies and ecologic data. This new conceptual framework is referred to as morphodynamics (Seilacher and Gishlick, 2014).

In conducting this research, Seilacher's true abilities as a visionary polymath become evident. His scientific scrutiny wandered across the constructional morphologies of bivalves, snails, sea urchins, mole crabs, shark teeth, ammonoids and many other groups of animals. In 1995, Seilacher resolved (for many of us) the mystery of the unlikely shape of Cretaceous heteromorphic ammonites, with his rather brilliant recognition that “many constructional and taphonomic incongruencies dissolve if ammonites are modeled as active Cartesian divers” (Seilacher and LaBarbera, 1995, p. 493). His insightful reconstruction of these unusually shaped ammonites is today a much more acceptable hypothesis than the one Dolf challenged, which ascribed the shape of these ammonites to desperate morphological radiation of animals that had become far too specialized for survival (nonsense in retrospect). It should be noted that the Cartesian diver hypothesis remains controversial (Briggs, personal communication, 2015). Seilacher was not finished with constructional morphology, as some of his last works included understanding the constructional morphology of crinoid holdfasts and Dolf's beautifully illustrated textbook Trace Fossil Analysis, which draws very heavily on Seilacher's deep knowledge of animal morphology and behavior.

Fossil art

While paleontologists have traditionally examined fossils directly to study life in different geological periods, Dolf utilized the camera lucida, a device that superimposes an image of the object on the drawing board, as the foundation of his research philosophy. Dolf indicated that the famous vertebrate paleontologist Professor Friedrich von Huene taught him to use the camera lucida, which has since remained his most important research aid. “You do not see what you have not drawn,” he stated (Fig. 7). As the lines come together, details and characteristics that are unique to the specimen appear, which can connect with countless others to provide evidence for underlying principles of paleontology (Vitek, 2010). During his PhD research at the Senckenberg Institute, Dolf interacted with Professor Wilhelm Schäfer, who also influenced his drafting style, As a result of Seilacher's magnificent art work, ichnology has a tradition of exceptional artist-scientists including Richard Bromley (best exemplified in Ekdale et al.; 1984 and Bromley, 1990), Tom Saunders (best exemplified in Pemberton et al., 2001), and Kerrie Bann (best exemplified in MacEachern et al., 2007, 2010), to name just a few.

Figure 7. Dolf drawing a fossil specimen with the camera lucida (photograph courtesy of Hans Luginsland).

Dolf, together with fossil preparator Hans Luginsland (Fig. 8A) and endowed with funds from the Craaford Prize (awarded by the Swedish Academy of Sciences), created the popular traveling exhibition “Fossil Art,” which displays fossils as works of art (Fig. 8B). For the past 20 years, it has traveled around the world with some 40 exhibits from prehistoric times. The final English version of the catalogue is Seilacher (2008) and a final German version was published in 2012 (Seilacher, 2012).

Figure 8. Fossil Art, A. Dolf with fossil preparator Hans Luginsland, B. The peel “Worm Burrow Jungle” from Fossil Art, C. The senior author with Dolf at the Fossil Art display at the 33rd International Geological Congress in Oslo, Norway in 2008. Note that Dolf is wearing his famous Paleodictyon tie.

Most of the specimens are casts of bedding surfaces upon which the activities and behaviors of ancient organisms are inscribed. “In this case we are taking casts of bedding planes on which currents, waves or other sedimentary processes have left patterns which are fascinating,” Professor Seilacher said. “The exhibit follows a two-step procedure emphasizing the emotional part as a first step followed by scientific analysis.” There are no text labels, only suggestive titles, as in an art gallery, with scientific explanation contained in the catalogue Fig. 8B).

“Fossil Art” focuses on patterns and shapes. Providing information on the scientific background is of secondary importance to the researcher, a fact evident from the fancy names given to the exhibits (e.g., “Trilobite Pirouette,” “Independence Day,” and “Life and Death in Dinosaur Park”). The exhibit has traveled the world for 18 years (1995–2013) and has been an integral part of many international meetings, including the 33rd International Geological Congress in Oslo, Norway, in 2008 (Fig. 8C). The exhibit was recently donated to the Senckenberg Museum, Frankfurt.

Conclusions

It is impossible to give Dolf his due credit or outline all of his contributions in one paper, but ichnology as a modern discipline owes its very existence to his insights and his genius. An old saying seems apropos at this time—Bernard of Chartres said that “we are like dwarves perched on the shoulders of giants, and thus we are able to see farther. And this is not at all because of the acuteness of our sight or the stature of our body, but because we are carried aloft and elevated by the magnitude of the giants.” What we admired most about Dolf was that he did science the way it was done in the past. Today, too much emphasis is placed on machines to do our thinking for us. Dolf was a Renaissance Man, relying simply on his powers of observation and his imagination. The only machine he used was the camera lucida to assist him in drawing the specimens that enabled him to understand the significance of what appeared to others to be minor details. Dolf Seilacher (Fig. 9) was certainly one of the giants of paleontology. We stand upon his shoulders to see further, and he will be sorely missed.

Figure 9. Dolf in 2008 with his ubiquitous cigar (photograph courtesy of Ulrike Seilacher).

Adolf “Dolf” Seilacher (1925–2014): Bibliography

Expanded from the list in Briggs (2005):

	Seilacher, A. 1943. Elasmobranchierreste aus dem oberen Muschelkalk und dem Keuper Württembergs. Neues Jahrbuch Mineralogie Geologie Paläontologie, 10(B): 256–271, 273–292.  Google Scholar
	Seilacher, A. 1948. Ein weiterer altertümlicher Elasmobranchier (Phoebodus keuperinus n. sp.) aus dem Württembergischen Gipskeuper. Neues Jahrbuch Mineralogie Geologie Paläontologie, 14(B): 24–27.  Google Scholar
	Seilacher, A. 1951. Der Röhrenbau von Lanice conchilega (Polychaeta).Ein Beitragzur Deutung fossilen Lebensspuren. Senckenbergiana, 32: 267–280.  Google Scholar
	Seilacher, A. 1953a. Studien zur Palichnologie.I. Über die Methoden der Palichnologie. Neues Jahrbuch für Geologie und Paläontologie- Abhandlungen, 96: 421–452.  Google Scholar
	Seilacher, A. 1953b. Studien zur Palichnologie.II. Die fossilen Ruhespuren (Cubichnia). Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 98: 87–124.  Google Scholar
	Seilacher, A. 1953c. Der Brandungssand als Lebensraum in Gegenwart und Vorzeit. Natur und Volk, 83: 263–273.  Google Scholar
	Seilacher, A. 1954a. Die geologische Bedeutung fossiler Lebensspuren. Zeitschrift Deutsche Geologische Gesellachaft, 105: 214–227.  Google Scholar
	Seilacher, A. 1954b. Okologie der Triassischen Muschel Lima lineata (Schloth.) und ihrer Epöken. Neues Jahrbuch für Geologie Paläontolologie Monatsh. 4: 163–183.  Google Scholar
	Seilacher, A. 1955a. Spuren und Lebensweise der Trilobiten. In Schindewolf, O.H. and Seilacher, A. (eds.). Beiträge zur Kenntnis des Kambriums in der Salt Range (Pakistan). Akademie Wissenschaften und der Literatur zu Mainz, Mathematisch-Natnaturwissenschaftliche Klasse, Abhandlungen, 1955(10): 342–372.  Google Scholar
	Seilacher, A. 1955b. Spuren und Fazies im Unterkambrium. In Schindewolf, O.H. and Seilacher, A. (eds.). Beiträge zur Kenntnis des Kambriums in der Salt Range (Pakistan). Akademie Wissenschaften und der Literatur zu Mainz, Mathematisch-Natnaturwissenschaftliche Klasse, Abhandlungen, 1955(10): 373–399.  Google Scholar
	Seilacher, A. 1956a. Ichnocumulus n. g., eine weitere Ruhespur des schwäbischen Jura. Neues für Geologie und Paläontologie- Monatshefte. 1956: 153–159.  Google Scholar
	Seilacher, A. 1956b. Der Beginn des Kambriums als biologische Wende. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 103: 155–180.  Google Scholar
	Seilacher, A. 1957. An-aktualistisches Wattenmeer? Paläontologische Zeitschrift 31: 198–206.  Google Scholar
	Seilacher, A. 1958. Zur Ökologischen Charakteristik von Flysch und Molasse. Eclogae Geologicae Helvetiae, 51: 1062–1078.  Google Scholar
	Seilacher, A. 1959a. Vom Leben der Trilobiten. Naturwissenschaften, 46: 389–393.  Google Scholar
	Seilacher, A. 1959b. Fossilien als Strömungsanzeiger. Aus der Heimat, 67: 170–177.  Google Scholar
	Seilacher, A. 1959c. Schnecken im Brandungssand. Natur und Volk, 89: 359–366.  Google Scholar
	Seilacher, A. 1960a. Epizoans as a key to ammonoid ecology. Journal of Paleontology, 34: 189–193.  Google Scholar
	Seilacher, A. 1960b. Strömungsanzeichen im Hunsrückschiefer. Notizblatt Hessisches Geologie Landesamt Bodenforschung, 88: 88–106.  Google Scholar
	Seilacher, A. 1960c. Lebensspuren als Leitfossilien. Geologische Rundschau, 49: 41–50.  Google Scholar
	Seilacher, A. 1961a. Ein Füllhorn aus dem Hunsrückschiefer. Natur und Volk, 91: 15–19.  Google Scholar
	Seilacher, A. 1961b. Krebse im Brandungssand. Natur und Volk, 91: 257–264.  Google Scholar
	Seilacher, A. 1961c. Holothurien im Hunsrückschiefer (Unter-Devon). Notizblatt Hessisches Geologie Landesamt Bodenforschung, 89: 66–72.  Google Scholar
	Seilacher, A. 1962a. Paleontological studies on turbidite sedimentation and erosion. Journal of Geology, 70: 227–234.  Google Scholar
	Seilacher, A. 1962b. Die Sphinctozoa, eine Gruppe fossiler Kalkschwämme. Akademie Wissenschaften und der Literatur zu Mainz, Mathematisch-Natnaturwissenschaftliche Klasse, Abhandlungen 1961(10): 721–790.  Google Scholar
	Seilacher, A. 1962c. Form und Funktion des Trilobiten-Daktylus. In Paläontologische Zeitschrift (H. Schmidt Festband), 218–227.  Google Scholar
	Seilacher, A. 1963a. Lebensspuren und Salinitäts- Fazies. Fortschritte in der Geologie von Rheinland Westfalen, 10: 81–94.  Google Scholar
	Seilacher, A. 1963b. Kaledonischer Unterbau der Irakiden. Neues Jahrbuch für Geologie Paläontolologie Monatshefte, 10: 527–542.  Google Scholar
	Seilacher, A. 1963c.Umlagerung und Rolltransport von Cephalopoden-Gehäusen. Neues Jahrbuch für Geologie und Paläontologie-Monatshefte, 11: 593–615.  Google Scholar
	Seilacher, A. 1964a. Biogenic sedimentary structures. In Imbrie, J. and Newell, N. (eds.). Approaches to Paleoecology. Wiley, New York, 296–316.  Google Scholar
	Seilacher, A. 1964b. Sedimentological classification and nomenclature of trace fossils. Sedimentology, 3: 253–256.  Google Scholar
	Seilacher, A. and Meischner, D. 1964. Fazies-Analyse im Paläozoikum des Oslo-Gebietes. Geologische Rundschau, 54: 596–619.  Google Scholar
	Seilacher, A. 1966. Lobenlibellen und Füllstrukturen bei Ceratiten. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 125: 480–488.  Google Scholar
	Seilacher, A. and Hemleben, C. 1966. Beitrage zur Sedimentation und Fossilführung des Hunsrückschiefers. 14. Spurenfauna und Bildungstiefe der Hunsrückschiefer (Unter-Devon). Notizblatt Hessisches Geologie Landesamt Bodenforschung, 94: 40–53.  Google Scholar
	Seilacher, A. 1967a. Tektonischer, sedimentologischer oder biologischer Flysch? Geologische Rundschau, 94: 40–53.  Google Scholar
	Seilacher, A. 1967b. Vorzeitliche Mäanderspuren. In Hediger, H. (ed.). Die Straßen der Tiere, Braunschweig, 294–306.  Google Scholar
	Seilacher, A. 1967c. Bathymetry of trace fossils. Marine Geology, 5: 413–428.  Google Scholar
	Seilacher, A. 1967d. Fossil behavior. Scientific America, 217: 72–80.  Google Scholar
	Seilacher, A. 1968a. Sedimentationsprozesse in Ammonitengehäusen. Akademie Wissenschaften und der Literatur zu Mainz, Mathematisch-Natnaturwissenschaftliche Klasse, Abhandlungen, 1967(9): 189–203.  Google Scholar
	Seilacher, A. 1968b. Swimming habits of belemnites—recorded by boring barnacles. Palaeogeography Palaeoclimatology Palaeoecology, 4: 279–285.  Google Scholar
	Seilacher, A. 1968c. Origin and diagenesis of the Oriskany Sandstone (Lower Devonian, Appalachian) as reflected in its shell fossils. In Müller, G. P. I. T. (ed.). Recent developments in carbonate sedimentology in Central Europe. Springer-Verlag, Heidelberg, Germany, 175–185.  Google Scholar
	Seilacher, A., Drozdzewski, H., and Haude, R 1968. Form and function of the stem in a pseudoplanctonic crinoid (Seirocrinus). Palaeontology, 11: 275–282.  Google Scholar
	Seilacher, A. 1969a. Paleoecology of boring barnacles. American Zoology, 9: 705–719.  Google Scholar
	Seilacher, A. 1969b. Fault-graded beds interpreted as seismites. Sedimentology, 13: 155–159.  Google Scholar
	Seilacher, A. 1969c. Sedimentary rhythms and trace fossils in Paleozoic sandstones of Libya. In Geology, Archaeology and Prehistory of the Southwestern Fezzan, Libya. Petroleum Exploration Society of Libya, Annual Fieldtrip Conference Guidebook 11: 117–122.  Google Scholar
	Seilacher, A. and Crimes, T. P. 1969. “European” species of trilobite burrows in eastern Newfoundland. In Kay, M. (ed.). North Atlantic Geology and Continental Drift. American Association Petroleum Geologists, Memoir, 12: 145–148.  Google Scholar
	Raup, D. and Seilacher, A. 1969. Fossil foraging behavior: computer simulation. Science, 166: 994–995.  Google Scholar
	Seilacher, A. 1970a. Begriff und Bedeutung der Fossil-Lagerstätten. Neues Jahrbuch für Geologie und Paläontologie-Monatshefte, 1970: 34–39.  Google Scholar
	Seilacher, A. 1970b. Cruziana stratigraphy of “non-fossiliferous” Palaeozoic sandstones. In Crimes, T. P. and Harper, J. C. (eds.). Trace Fossils. Geolological Journal Special Issue, 3: 447–476.  Google Scholar
	Seilacher, A. 1971a. Arbeitskonzept zur Konstruktions-Morphologie. Lethaia, 3: 393–396.  Google Scholar
	Seilacher, A. 1971b. Preservational history of ceratite shells. Palaeontology, 14: 16–21.  Google Scholar
	Goldring, R. and Seilacher, A. 1971. Limulid undertracks and their sedimentologic implications. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 137: 422–442.  Google Scholar
	Seilacher, A. and Westphal, F. 1971. “Fossil-Lagerstätten.” In Miller, G. (ed.). Sedimentology of Parts of Central Europe. Verlag Waldemar Kramer, Frankfurt, Germany, 327–335.  Google Scholar
	Seilacher, A. 1972. Divaricate patterns in pelecypod shells. Lethaia, 5: 325–343.  Google Scholar
	Seilacher, A. 1973a. Biostratinomy: the sedimentology of biologically standardized particles. In Ginsburg, R. (ed.). Evolving Concepts in Sedimentology. Johns Hopkins University Press, Baltimore, 159–177.  Google Scholar
	Seilacher, A. 1973b. Fabricational noise in adaptive morphology. Systematic Zoology, 22: 451–465.  Google Scholar
	Seilacher, A. 1974a. Flysch trace fossils: evolution of behavioural diversity in the deep-sea. Neues Jahrbuch für Geologie und Paläontologie-Monatshefte, 4: 233–245.  Google Scholar
	Seilacher, A. 1974b. Vorzeitliche Umwelt. Die Arbeit des Tübinger Sonderforschungsbereichs 53. Tübinger University Zeitung, 54–58.  Google Scholar
	Seilacher, A. 1975. Mechanische simulation und funktionelle evolution des ammoniten-septums. Paläontologische Zeitschrift, 49: 268–286.  Google Scholar
	Seilacher, A., Andalib, F., Dietl, G., and Gocht, H. 1976. Preservational history of compressed Jurassic ammonites from southern Germany. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 152: 307–356.  Google Scholar
	*Seilacher, A. 1976a. Echinodermen-Lagerstätten. Zentralblatt für Geologie und Paläontolologie Teil II, 1976: 227–231.  Google Scholar
	*Seilacher, A. 1976b. Photosymbiontische Muscheln. Zentralblatt für Geologie und Paläontolologie Teil II, 1976: 303–305.  Google Scholar
	*Seilacher, A. 1976c Konstruktionsmorphologische Lizenzen des Echinodermen-Skeletts. Zentralblatt für Geologie und Paläontolologie Teil II, 1976: 306–311.  Google Scholar
	*Seilacher, A. 1976d. Ammoniten-Erhaltung. Zentralblatt für Geologie und Paläontolologie Teil II, 1976: 355–362.  Google Scholar
	*Seilacher, A. 1976e. Phosphat-Diagenese im marinen Milieu. Zentralblatt für Geologie und Paläontolologie Teil II, 1976: 371–377.  Google Scholar
	*Seilacher, A. 1976f. Evolution von Spuren- Vergesellschaftungen. Zentralblatt für Geologie und Paläontolologie Teil II, 1976: 396–402.  Google Scholar
	Seilacher, A. 1977a. Evolution of trace fossil communities. In Hallam, A. (ed.). Patterns of Evolution. Elsevier, Amsterdam, The Netherlands, 359–376.  Google Scholar
	Seilacher, A. 1977b. Pattern analysis of Paleodictyon and related trace fossils. In Crimes, T. P. and Harper, J. C. (eds.). Trace Fossils 2. Geological Journal Special Issue 9: 289–334.  Google Scholar
	Seilacher, A. 1977c. Facies problems in Cruziana stratigraphy. Journal Paleontology, 51: 25.  Google Scholar
	Seilacher, A. 1978a. Use of trace fossil assemblages for recognizing depositional environments. In Basan, P. (ed.). Trace Fossil Concepts. Society of Economic Paleontologists and Mineralogists, Short Course, 5: 167–180.  Google Scholar
	*Seilacher, A. 1978b. Constructional morphology and evolutionary ecology of sand dollars. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 157: 169–172.  Google Scholar
	*Seilacher, A. 1978c. Evolution of trace fossils communities in the deep sea. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 157: 251–255.  Google Scholar
	*Seilacher, A. and Westphal, F. 1978. Paleoecology, constructions, sedimentology, diagenesis and association of fossils. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 157: 1–2.  Google Scholar
	*Brenner, K. and Seilacher, A. 1978. New aspects about the origin of the Toarcian Posidonia Shales. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 157: 11–18.  Google Scholar
	*Seilacher, A. and Wiesenauer, E. 1978. Preservational and adaptational history of belemnites. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 157: 145–149.  Google Scholar
	Seilacher, A. 1979. Constructional morphology of sand dollars. Paleobiology, 5: 191–221.  Google Scholar
	Frey, R.W. and Seilacher, A. 1980. Uniformity in marine invertebrate ichnology. Lethaia, 13: 183–207.  Google Scholar
	Seilacher, A. 1981a. Towards an evolutionary stratigraphy. Acta Geologica Hispanica, 16: 39–44.  Google Scholar
	Seilacher, A. 1981b. Konstruktionsmorphologie von Muschelgehäusen. Paläontologische Kursbücher 1: 173–186.  Google Scholar
	Seilacher, A. 1982a. Ammonite shells as habitats in the Posidonia Shales of Holzmaden—floats or benthic islands? Neues Jahrbuch für Geologie und Paläontologie-Monatshefte, 2: 98–114.  Google Scholar
	Seilacher, A. 1982b. Posidonia shales (Toarcian, S. Germany)—stagnant basin model revalidated. In Motanaro Gallitelli, E. (ed.). Palaeontology, Essential of Historical Geology: Proceedings of the First International Meeting on Palaeontology, Essential of Historical Geology. Venice, Italy, June 2–4, 1981. S.T.E.M. Mucchi, Modena, Italy, 279–298.  Google Scholar
	*Seilacher, A. 1982c. Erfolgte die Ammoniten-Besiedlung im Holzmadener Posidonienschiefer vor oder nach dem Absinken? Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 164: 31.  Google Scholar
	*Seilacher, A. 1982d. “Hammer oysters” as secondary soft bottom dwellers. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 164: 245–250.  Google Scholar
	Seilacher, A. 1982e. General remarks about event deposits. In Einsele, G. and Seilacher, A. (eds.). Cyclic and Event Stratification. Springer-Verlag, Heidelberg, Germany, 161–174.  Google Scholar
	Seilacher, A. 1982f. Distinctive features of sandy tempestites. In Einsele, G. and Seilacher, A. (eds.). Cyclic and Event Stratification. Springer-Verlag, Heidelberg, Germany, 333–349.  Google Scholar
	Seilacher, A. 1982g. Ammonite shells as habitats—floats or benthic islands? In Einsele, G. and Seilacher, A. (eds.). Cyclic and Event Stratification. Springer-Verlag, Heidelberg, Germany, 504.  Google Scholar
	*Ghiold, J. and Seilacher, A. 1982. Burrowing strategies. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 164: 221–228.  Google Scholar
	*Chinzei, K., Savazzi, E., and Seilacher, A. 1982. Adaptational strategies of bivalves living as infaunal secondary soft bottom dwellers. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 164: 229–244.  Google Scholar
	Seilacher, A. 1983a. Palökologie—Wechselwirkung zwischen geologischen und biologischen Prozesser. In Seibold, E. (ed.). Forschung in der Bundesrepublik Deutschland. Weinheim, DFG, Verlag Chemie GmbH, 689–696.  Google Scholar
	Seilacher, A. 1983b. Upper Paleozoic trace fossils from the Gilf-Kebir-Abu-Ras area in southwestern Egypt. Journal of African Earth Science, 1: 21–34.  Google Scholar
	Seilacher, A. 1983c. Papers on cephalopod palaeobiology and phylogeny. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 165: 327–329.  Google Scholar
	Seilacher, A. 1984a. Sedimentary structures tentatively attributed to seismic events. Marine Geology, 55: 1–12.  Google Scholar
	Seilacher, A. 1984b. Storm beds: Their significance in event stratigraphy. In Seibold, E. and Meulenkamp, J. D. (eds.). Stratigraphy quo vadis? Tulsa, OK, American Association of Petroleum Geologists, Studies in Geology, 16: 49–54.  Google Scholar
	Seilacher, A. 1984c. Constructional morphology of bivalves: Evolutionary pathways in primary versus secondary soft-bottom dwellers. Palaeontology, 27: 207–237.  Google Scholar
	Seilacher, A. 1984d. Late Precambrian and early Cambrian Metazoa: Preservational or real extinctions. In Holland, H. D. and Trendall, A. F. (eds.). Patterns of Change in Earth Evolution. Dahlem Konferenzen, May 1–6, 1983, Springer-Verlag, Heidelberg, Germany, 159–168.  Google Scholar
	Seilacher, A. 1985a. The Jeram model: Event condensation in a modern intertidal environment. In Bayer, U. and Seilacher, A. (eds.). Sedimentary and Evolutionary Cycles. Springer-Verlag, Heidelberg, Germany, 336–341.  Google Scholar
	Seilacher, A. 1985b. Bivalve morphology and function. In Bottjer, D. J. Hickman, C. S., and Ward, P. D. (eds.). Mollusks: Notes for a Short Course Sponsored by the Paleontological Society, University of Tennesse, Knoxville, Tennessee, 88–101.  Google Scholar
	Seilacher, A. 1985c. Discussion of Precambrian metazoans. Philosophical Transactions of the Royal Society of London Series B, 311: 47–48.  Google Scholar
	Seilacher, A. 1985d. Trilobite palaeobiology and substrate relationships. Transactions Royal Society of Edinburgh, 76: 231–237.  Google Scholar
	Seilacher, A., Reif, W.-E., and Westphal, F. 1985. Sedimentological, ecological and temporal patterns of fossil Lagerstätten. Philosophical Transactions of the Royal Society of London Series B, 311: 5–23.  Google Scholar
	Seilacher, A., Matyja, B.A. and Wierzbowski, A. 1985. Oyster beds: Morphological response to changing substrate conditions. In Bayer, U. and Seilacher, A. (eds.). Sedimentary and Evolutionary Cycles. Heidelberg, Springer-Verlag Heidelberg, Germany, 421–435.  Google Scholar
	Seilacher, A. 1986. Evolution of behavior as expressed in marine trace fossils. In Nitecki, M. H. and Kitchell, J. A. (eds.). Evolution of Animal Behavior: Paleontological and Field Approaches. Oxford University Press, New York, 62–87.  Google Scholar
	Seilacher, A. and Seilacher-Drexler, E. 1986. Sekundäre Weichbodenbewohner unter den Cirripediern. Paläontologische Zeitschrift, 60: 75–92.  Google Scholar
	Alidou, S., Lang, J. Bonvalot J., Roman, E., and Seilacher, A. 1986. Elements de datation en faveur d'un age Paleozoique et Mesozoique du bassin de Kandi (Nord-Est du Benin,Afrique de l'Ouest). Journal of African Earth Science, 5: 339–344.  Google Scholar
	Seilacher, A., Reif, W.-E., Frey, E., Riess, J. and Saure, C. 1987. Bauprinzipien und Evolution der Skelette von Tieren. Sonderforschungsbereich Bl/B3, Arcus, 16–21.  Google Scholar
	Seilacher, A. 1988a. Why are nautiloid and ammonite sutures so different? Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 177: 41–69.  Google Scholar
	Seilacher, A. 1988b. Schlangensterne (Aspidura) als Schlüssel zur Entstehungsgeschichte des Muschelkalks. Neue Forschungen zur Erdgeschichte von Crailsheim, Sonderband Gesellschaft für Naturkunde in Württemberg, 1: 85–98.  Google Scholar
	Seilacher, A. and Alidou, S. 1988. Ordovician and Silurian trace fossils from northern Benin (W. Africa). Neues Jahrbuch für Geologie und Paläontologie, 7: 431–439.  Google Scholar
	Seilacher, A. and Chinzei, K. 1988. Selbstbildungs- Mechanismen als Prozessoren organismischer Entwicklung und Evolution. Leichtbau in Architektur und Natur, Natürliche Konstruktionen, 3: 55–63.  Google Scholar
	Seilacher, A. 1989a.Vendozoa: organismic construction in the Proterozoic biosphere. Lethaia, 22: 229–239.  Google Scholar
	Seilacher, A. 1989b. Spirocosmorhaphe, a new graphoglyptid trace fossil. Journal of Paleontology, 63: 116–117.  Google Scholar
	Seilacher, A. and Chinzei, K. 1989. Selbstbildungs-Mechanismen als Processoren organischer Entwicklung und Evolution. Natürliche Konstruktionen, Mitteilungen des SFB, 230: 55–64.  Google Scholar
	Seilacher, A. 1990a. Aberrations in bivalve evolutionrelated to photo- and chemosymbiosis. Historical Biology, 3: 289–311.  Google Scholar
	Seilacher, A. 1990b. Paleozoic trace fossils. In Said, R. (ed.). The Geology of Egypt. Balkema, Rotterdam, The Netherlands, 1565–1581.  Google Scholar
	Seilacher, A. 1990c.Taphonomy of fossil-Lagerstätten: overview. In Briggs, D. E. G. and Crowther, P. R. (eds.). Palaeobiology, A Synthesis. Blackwell Science Publication, Oxford, 266–270.  Google Scholar
	Seilacher, A. 1990d. Die Holzmadener Posidonienschiefer: Entstehung der Fossillagerstätte und eines Erdölmuttergesteins. In Weidert, W. K. (ed.). Klassische Fundstellen der Paläontologie. Goldschneck-Verlag, Korb, Germany, 107–131.  Google Scholar
	Seilacher, A. 1990e. The sand dollar syndrome: a polyphyletic evolutionary breakthrough. In Nitecki, M. H. (ed.). Evolutionary Innovations. University of Chicago Press, Chicago, 231–252.  Google Scholar
	Seilacher, A. 1991a. Self-organizing mechanisms in morphogenesis and evolution. In Schmidt-Kittler, N. and Vogel, K. (eds.). Constructional Morphology and Evolution. Springer-Verlag, Heidelberg, Germany, 251–271.  Google Scholar
	Seilacher, A. 1991b. Precambrian evolutionary experiments: Vendozoa and Psammocorallia. In Alberch, P. and Dover, G. A. (eds.). The Reference Points in Evolution. Fundacion Juan March, Madrid, 48–53.  Google Scholar
	Seilacher, A. 1991c. Morphologic transformation in the wake of behavioral change. In Alberch, P. and Dover, G. A. (eds.). The Reference Points in Evolution. Fundacion Juan March, Madrid, 80–82.  Google Scholar
	Seilacher, A. 1991d. Self-organization: Morphogenetic mechanisms as processors of evolution. Revista Española Paleontologia Extraordinario, 5: 5–11.  Google Scholar
	Seilacher, A. 1991e. Was Fossilien erzählen, oder: zur Taphonomie und Diagenese von Kreidefeuersteinen. Fossilien, 4: 210–214.  Google Scholar
	Seilacher, A. 1991f. Events and their signatures— an overview. In Einsele, G., Ricken, W. and Seilacher, A. (eds.). Cycles and Events in Stratigraphy. Springer-Verlag, Heidelberg, Germany, 222–226.  Google Scholar
	Seilacher, A. 1991g. “Medusoid” salt pseudomorphs. Journal of Paleontology, 65: 330.  Google Scholar
	Leszcynski, S. and Seilacher, A. 1991. Ichnocoenoses of a turbidite sole. Ichnos 1: 293–303.  Google Scholar
	Alidou, S., Lang, J. Bonvalot, J., Roman, E. and Seilacher, A. 1991. Marine influences in the socalled continental sediments of the Paleozoic- Mesozoic Kandi Basin (Northern Benin, West Africa). Journal of African Earth Science, 12: 55–65.  Google Scholar
	Seilacher, A. and Aigner, T. 1991. Storm deposition at the bed, facies, and basin scale: the geologic perspective. In Einsele, G., Ricken, W. and Seilacher, A. (eds.). Cycles and Events in Stratigraphy. Springer-Verlag, Heidelberg, Germany, 249–267.  Google Scholar
	Brett, C. E. and Seilacher, A. 1991. A taphonomic consequence of event sedimentation. In Einsele, G., Ricken, W. and Seilacher, A. (eds.). Cycles and Events in Stratigraphy. Springer-Verlag, Heidelberg, Germany, 283–297.  Google Scholar
	Einsele, G. and Seilacher, A. 1991. Distinction of tempestites and turbites. In Einsele, G., Ricken, W. and Seilacher, A. (eds.). Cycles and Events in Stratigraphy. Springer-Verlag, Heidelberg, Germany, 377–382.  Google Scholar
	Pflüger, F. and Seilacher, A. 1991. Flash flood conglomerates. In Einsele, G., Ricken, W. and Seilacher, A. (eds.). Cycles and Events in Stratigraphy. Springer-Verlag, Heidelberg, Germany, 383–439.  Google Scholar
	Savrda, C. E., Bottjer, D. J. and Seilacher, A. 1991. Redox-related benthic events. In Einsele, G., Ricken, W. and Seilacher, A. (eds.). Cycles and Events in Stratigraphy. Springer-Verlag, Heidelberg, Germany, 524–541.  Google Scholar
	Seilacher, A. 1992a.Vendobionta and Psammocorallia: Lost constructions of Precambrian evolution. Journal Geological Society London, 149: 607–613.  Google Scholar
	Seilacher, A. 1992b. Whale barnacles: How an evolutionary dream could become true. Mitteilungen des SFB 230, Natürliche Konstruktionen, 8: 131–136.  Google Scholar
	Seilacher, A. 1992c. Event stratigraphy: Dynamic view of the sedimentary record. In Brown, G., Hawkesworth, C. and Wilson, C. (eds.). Understanding the Earth. Cambridge University Press, Cambridge, 375–385.  Google Scholar
	Seilacher, A. 1992d. How to proceed and succeed in paleontology. Europal, 1: 11–13.  Google Scholar
136	Seilacher, A. 1992e. Vendobionta: strangest organisms on earth and evolution of trace fossils. In Alvarez, F. (ed.). Palaeobiology: Preparing for the twenty-first century. Instituto Juan March de Estudios e Investigaciones, Centro de Reuniones Internacionales sobra Biologia, 3: 57–74.  Google Scholar
	Seilacher, A. 1992f. Self-organization of morphologies. In Alvarez, F. (ed.), Palaeobiology: Preparing for the twenty-first century. Instituto Juan March de Estudios e Investigaciones, Centro de Reuniones Internacionales sobra Biología, 3: 89–100.  Google Scholar
	Seilacher, A. 1992g. Dynamic taphonomy: the process-related view of Fossil-Lagerstätten. In Fernandez Lopes, S. (ed.). Conferencias de la Reunión de Tafonomía y Fosilización. Complutense, Madrid, 109–125.  Google Scholar
	Seilacher, A. 1992h. Quo vadis, ichnology? In Maples, C. G. and West, R. R. (eds.). Trace Fossils. Paleontology Society, Short Courses in Paleontology, 5: 224–238.  Google Scholar
	Seilacher, A. 1992i. Präkambrisches Leben. Protoplasma in Luftmatratzen, Tübingen Universität, 52: 4–5.  Google Scholar
	Seilacher, A. 1992j.Vendobionta als Alternative zu Vielzellern. 34. Phylogenetisches Symposium; 1991 Dec 13–15; Hamburg. Mitteilungen aus den Hamburgischen Zoologischen Museum und Institut, 89: 9–20.  Google Scholar
	Seilacher, A. 1992k. An updated Cruziana stratigraphy of Gondwanan Paleozoic sandstones. In Salem, M. J., Hammuda, O. S. and Eliagoubi, B. A. (eds.). The Geology of Libya, Vol. 4. Elsevier, Amsterdam, 1565–1581.  Google Scholar
	Seilacher, A., Seilacher, P. and Seilacher, U. 1992. Bonebed-Bildungen am heutigen Amazonas. Fossilien, 4: 246–248.  Google Scholar
	Seilacher, A. and Pflüger, F. 1992. Trace fossils from the late Proterozoic of North Carolina: early conquest of deep-sea bottoms. In Lidgard, S. and Crane, P. R. (eds.). Fifth North American Paleontological Convention: Abstracts and Program. Paleontology Society, Washington, DC, 265 p.  Google Scholar
	Seilacher, A. 1993a. Ammonite aptychi: how to transform a jaw into an operculum. In Dodson, P. and Gingerich, P. (eds.). Functional Morphology and Evolution. Kline Geological Laboratory Yale University, New Haven, CT, 20–32. ( American Journal of Science, Special volume, 293A)  Google Scholar
	Seilacher, A. 1993b. Fossil-Lagerstätten im Muschelkalk. In Hagdorn, H. and Seilacher, A. (eds.). Muschelkalk, Schöntaler Symposium 1991. Sonderbände der Gesellschaft für Naturkunde in Württeberg, 2: 213–222.  Google Scholar
	Seilacher, A. 1993c. Problems of correlation in the Nubian sandstone facies. In Thorweihe, U. and Schandelmeier, H. (eds.). Geoscientific Research in Northeast Africa. Rotterdam, Balkema, 329–333.  Google Scholar
	Seilacher, A. and Klug, C. 1993. Selbst-Organisation bei Kerzenmuscheln. Naturwissenschaftliche Rundschau, 46: 132–134.  Google Scholar
	Skwarko, S. K. and Seilacher, A. 1993. Trace fossils and problematica. In Skwarko, S. K. (ed.). Palaeontology of the Permian of Western Australia. Geological Survey Western Australia Bulletin 136: 390–403.  Google Scholar
	Seilacher, A. and Chinzei, K. (eds.). 1993. Progress in constructional morphology. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 190: 165–167.  Google Scholar
	Chinzei, K. and A. Seilacher. 1993. Remote biomineralization I: Fill skeletons in vesicular oyster shells. Neues Jahrbuch für Geologie und Paläontologie- Abhandlungen, 190: 185–197.  Google Scholar
	Seilacher, A. and Chinzei, K. 1993. Remote biomineralization II: Fill skeletons controlling buoyancy in shelled cephalopods. Neues Jahrbuch für Geologie und Paläontologie- Abhandlungen, 190: 199–208.  Google Scholar
	Seilacher, A. and Gunji. Y. P. 1993. Morphogenetic countdown: another view on heteromorphy shells in gastropods and ammonites. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 190: 73–101.  Google Scholar
	Seilacher, A. 1994a. Candle wax shells, morphodynamics and the Cambrian explosion. Acta Palaeontologica Polonica, 38: 273–280.  Google Scholar
	Seilacher, A. 1994b. Self-organized structures in the evolution of early life. In Natürliche Konstruktionen, Mitteilungen des SFB 230, Natürliche Konstruktionen, 9: 303.  Google Scholar
	Seilacher, A. 1994c. Early multicellular life: Late Proterozoic fossils and the Cambrian explosion. In Bengtson, S. (ed.). Early Life on Earth. Columbia University Press, New York, 389–400.  Google Scholar
	Seilacher, A. 1994d. How valid is Cruziana stratigraphy? Geologische Rundschau, 83: 752–758.  Google Scholar
	Seilacher, A. 1994e. Response to Paleontology Society medal. Journal of Paleontology, 68: 917–918.  Google Scholar
	Seilacher, A. and Seilacher-Drexler, E. 1994. Bivalve trace fossils: A lesson from actuopaleontology. Senckenbergiana Lethaea, 72: 5–15.  Google Scholar
	Buss, L. and Seilacher, A. 1994. The phylum Vendobionta: A sister group of the Eumetazoa? Paleobiology, 20: 1–4.  Google Scholar
	Seilacher, A. and Pflüger, F. 1994. From biomats to benthic agriculture: a biohistoric revolution. In Krumbein, W., Paterson, D. M. and Stal, L. J. (eds.). Biostabilization of sediments. Bibliotheks-und Informationssystem der Carl von Ossietzky Universität Odenburg, 97–105.  Google Scholar
	Seilacher, A. 1995a. Fossile Kunst: Albumblätter der Erdgeschichte. Goldschneckverlag, Korb, Germany 48 p.  Google Scholar
	Seilacher, A. 1995b. Black shale models: An observational approach. Europal, 8: 23–25.  Google Scholar
	Seilacher, A. 1995c. Selbstorganisation in der Frühen Evolution des Lebens. Jahreshefte Gesellschsft für Naturkunde in Wüerttemberg, 151: 73–82.  Google Scholar
	Penalver, E. and Seilacher, A. 1995. Rubielos de Mora: eine untermiozäne Fossil Lagerstätte. Fossilien, 4: 211–216.  Google Scholar
	Seilacher, A. and LaBarbera, M. 1995. Ammonites as Cartesian divers. Palaios, 10: 493–506.  Google Scholar
	Maeda, H. and Seilacher, A. 1996. Ammonoid taphonomy. In Landman, N. H., Tanabe, K. and Davis, R. A. (eds.). Ammonoid Paleobiology. Plenum Press, New York, 543–578.  Google Scholar
	Seilacher, A. 1996a. Explosive evolution in the Precambrian/Cambrian transition. In Molina, E. (ed.). Evolución: aspectos interdisciplinares. Semester Interdiscip. University Zaragoza, Zaragoza, Spain, 15–20. ( Cuadernos Interdiscip 6)  Google Scholar
	Seilacher, A. 1996b. Great revolutions in the history of life [in Japanese]. In Morita, R. (ed.). Guidebook for the Special Exhibition of the Natural History Museum and Institute. Syobundo, Chiba, Japan, 2–6.  Google Scholar
	Seilacher, A. 1996c. Evolution of burrowing behavior in Silurian trilobites: Ichnosubspecies of Cruziana acacensis. In Salem, M. J., Mouzughi, A. J. and Hammuda, O. S. (eds.). The Geology of Sirt Basin, Vol. 1. Elsevier, Amsterdam, 523–530.  Google Scholar
	Kull, U., Maier, W., Nachtigall, W. and Seilacher, A. 1996. Funktions-und Konstruktionsmorphologie. In Teichmann, K. and Wilke, I. (eds.). Prozess und Form “Natürlicher Konstruktionen.” Ernst and Sahn Verlag, Berlin, 34–51.  Google Scholar
	Seilacher, A. and Goldring, R. 1996. Class Psammocorallia (Coelenterata, Vendian-Ordovician): recognition, systematics and distribution. Geologiska Foreningens i Stockholm Forhandlingar, 118: 207–216.  Google Scholar
	Gehling, J. G., Runnegar, B., and Seilacher, A. 1996. Rasping markings of large Metazoan grazers, terminal Neoproterozoic of Australia and Cambrian(?) of Saudi Arabia; SEPM meeting abstracts. Tulsa, OK: SEPM (Society for Sedimentary Geology), 100 p.  Google Scholar
	Seilacher, A. 1997a. Sandkorallen: Ein ausgestorbener Lebensformtyp. Fossilien, 2: 79–84.  Google Scholar
	Seilacher, A. 1997b.Great revolutions in the history of life. Journal Natural History Museum Institute Chiba, 4: 87–91.  Google Scholar
	Seilacher, A. 1997c. Fossil art. Journal Natural History Museum Institute Chiba, 4: 93–95.  Google Scholar
	Seilacher, A. 1997d. Fondement écologique et conséquences de l'explosion cambrienne [The ecological base and consequences of the Cambrian explosion]. Geobios (mem spec.) 21: 229–233.  Google Scholar
	Seilacher, A. 1997e. Austern und Rudisten—ein konstruktionsmorphologischer Vergleich. Courier Forschungsinstitut Senckenberg, 201: 421–432.  Google Scholar
	Seilacher, A. 1997f.Warum fossile Fährten oft nur bergauf gehen. Fossilien, 6: 372–375.  Google Scholar
	Seilacher, A. 1997f. Für Eddi Klitzsch. In Schandelmeier, H. and Reynolds, P. (eds.). Palaeogeographic–Palaeotectonic Atlas of North-eastern Africa, Arabia, and Adjacent Areas—Late Neoproterozoic to Holocene. Rotterdam, Balkema, 15–16.  Google Scholar
	Seilacher, A. 1997g. Fossil art: An exhibition of the Geologisches Institut Tübingen University, Germany. Drumheller, Alberta, Canada, Royal Tyrell Museum of Palaeontology, 64 p.  Google Scholar
	Seilacher, A. 1997h. The meaning of the Cambrian explosion. Bulletin National Museum of Natural Science Peking, China, 10: 1–9.  Google Scholar
	Fortey, R. A. and Seilacher, A. 1997.The trace fossil Cruziana semiplicata and the trilobite that made it. Lethaia, 30: 105–112.  Google Scholar
	Seilacher, A. 1998a. “Sue”—Das teuerste Fossil aller Zeiten. Fossilien, 4: 236–238.  Google Scholar
	Seilacher, A. 1998b: Rudists as bivalvian dinosaurs. In Johnston, P. A. and Haggart, J. (eds.). Bivalves: An eon of evolution. University of Calgary Press, Calgary, Alberta, 423–436. ( Paleobiological studies honoring Norman D. Newell)  Google Scholar
	Seilacher, A. 1998c. Mosasaurs, limpets or diagenesis: How Placenticeras shells got punctured. Mitteilungen Museum Naturkunde Berlin Geowissenschaftlichen Reihe, 1: 93–102.  Google Scholar
	Seilacher, A. 1998d. Schemas de macroevolution, comment se preparer a l'extinction? [Patterns of macroevolution: how to be prepared for extinction]. Comptes Rendus de l'Académie des Sciences, Sciences de la Terre Planètes, 327: 431–440.  Google Scholar
	Kase, T., Johnston, P. A., Seilacher, A. and Boyce, G. B. 1998. Alleged mosasaur marks on Late Cretaceous ammonites are limpet (patellogastropod) home-scars. Geology, 26: 947–950.  Google Scholar
	Seilacher, A., Bose, P., Pfluger, P. and Pflüger, F. 1998. Triploblastic animals more than 1 billion years ago: Trace fossil evidence from India. Science, 282: 80–83.  Google Scholar
	Seilacher, A. 1999a. Oecoptychius Rätsel. Fossilien, 3: 131.  Google Scholar
	Seilacher, A. 1999b. Pinna. Fossilien, 3: 138.  Google Scholar
	Seilacher, A. 1999c. Biomat-related life styles in the Precambrian. Palaios, 14: 86–93.  Google Scholar
	Seilacher, A. 1999d. Erdgeschichte als Langzeit- Experiment: die großen Revolutionen in der Entwicklung des Lebens. Eclogae Geologicae Helvetiae, 92: 73–79.  Google Scholar
	Seilacher, A. 1999e. Ediacaran biota. In Singer, R. (ed.). Encyclopedia of Paleontology. Fitzroy Dearborn Pubication, Chicago, 391–397.  Google Scholar
	Omarini, R. H., Sureda, R. I., Götze, H.-J., Seilacher, A. and Pflüger, F. 1999. Puncoviscana folded belt in northwestern Argentina: testimony of Late Proterozoic Rodinia fragmentation and pre-Gondwana collisional episodes. International Journal of Earth Science, 88: 76–97.  Google Scholar
	Keupp, H., Röper, M. and Seilacher, A. 1999. Paläobiologische Aspekte von syn vivo-besiedehen Ammonoideen im Plattenkalk des Ober-Kimmeridgiums von Brunn in Ostbayern. Berliner Geowissenschaften Abhandlungen, E 30: 121–145.  Google Scholar
	Seilacher-Drexler, E. and Seilacher, A. 1999. Undertraces of sea pens and moon snails. Neues Jahrbuch für Geologie und Paläontologie- Abhandlungen, 214: 195–210.  Google Scholar
	Eklöf, J., Rydell, J., Fröjmark, J., Johansson, M. and Seilacher, A. 1999. Orientation of agnostid shields in Alum Shale (Upper Cambrian): implications for the depositional environment. Geologiska Foreningens i Stockholm Forhandlingar, 121: 301–306.  Google Scholar
	Seilacher, A. 2000a. Fossillagerstätten, Literaturbericht. Zentralblatt für Geologie und Paläontologie Teil II, Heft 5/6, 1999: 363–373.  Google Scholar
	Seilacher, A. 2000b.Ammoniten als Kartesische Taucher? Fossilien, 4: 231–237.  Google Scholar
	Seilacher, A. 2000c. Leben im Präkambrium. Naturwissenschaften Rundschau, 629: 553–558.  Google Scholar
	Seilacher, A. 2000d. Ordovician and Silurian arthrophycid ichnostratigraphy. In Sola, M. A. and Worsely, D. (eds.). Geological Exploration in Murzuq Basin. Elsevier, Amsterdam, 237–258.  Google Scholar
	Seilacher, A., Meschede, A., Bolton, E. W. and Luginsland, H. 2000. Precambrian “fossil” Vermiforma is a tectograph. Geology, 28: 235–238.  Google Scholar
	Seilacher, A. and Keupp, H. 2000. Wie sind Ammoniten geschwommen? Fossilien, 5: 310–313.  Google Scholar
	Seilacher, A., Marshall, C., Skinner, H. C.W. and Tsuihiji, T. 2001. A fresh look at sideritic “coprolites.” Paleobiology, 27: 7–13.  Google Scholar
	Seilacher, A. 2001. Concretion morphologies reflecting diagenetic and epigenetic pathways. Sedimentary Geology, 143: 41–57.  Google Scholar
	Rydell, J., Hammarlund, I. and Seilacher, A. 2001. Trace fossils associations in the Mickwitzia sandstone (Lower Cambrian): did trilobites really hunt for worms? Geologiska Foreningens i Stockholm Forhandlingar, 123: 247–250.  Google Scholar
	Omarina, R. H., Sureda, R. J., Götze, H. J., Seilacher, A. and Pflüger, F. 2001. Puncoviscana, folded belt in northwestern Argentina: Testimony of Late Proterozoic Rodinia fragmentation and pre-Gondwana collisional episodes: a reply. International Journal of Earth Science, 90: 894–902.  Google Scholar
	Seilacher, A. 2002. Non olet: The strange taphonomy of coprolites and cololites. In De Renzi, M., Alonso, M. W. P., Belinchon, M., Penalver, E., Montoya, P. and Marques-Aliaga, A. (eds.). Current Topics on Taphonomy and Fossilization. Valencia, Ajuntament de Valencia, 233–240.  Google Scholar
	Grazhdankin, D. and Seilacher A. 2002.Underground vendobionta from Namibia. Palaeontology, 45: 57–78.  Google Scholar
	Seilacher, A., Lüning, S., Martin, M. A., Klitzsch, E., Khja, A. and Craig, J. 2002. Ichnostratigraphic correlation of Lower Palaeozoic clastics in the Kufra Basin (SE Libya). Lethaia, 35: 257–262.  Google Scholar
	Seilacher, A. 2003a.Vendobionts (Precambrian evolution). In McGraw-Hill 2003 Yearbook of Science and Technology. McGraw-Hill, New York, 458–461.  Google Scholar
	Seilacher, A. 2003b. Der Garten von Ediacara und die Kambrische Explosion. In Hansch, W. (ed.). Katastrophen in der Erdgeschichte—Wendezeiten des Lebens. Heilbronn, Städ. Museo, 19: 70–81.  Google Scholar
	Seilacher, A. 2003c. Anrüchig? Koprolithen und Cololithen. Fossilien, 4: 230–233.  Google Scholar
	Seilacher, A., Grazhdankin, D. and Legouta, A. 2003. Ediacaran biota: the dawn of animal life in the shadow of giant protists. Paleontological Research, 7: 43–54.  Google Scholar
	Simon, T., Hagdorn, H., Hagdorn, M. K. and Seilacher, A. 2003. Swimming trace of a coelacanth fish from the Lower Keuper of south-west Germany. Palaeontology, 46: 911–926.  Google Scholar
	Seilacher, A., Cingolani, C. and Varela, R. 2003. Ichnostratigraphic correlation of early Paleozoic quartzites in North Africa and central Argentina. In Salem, M. J., Oun, K. M. and Dessiq, H. M. (eds.). The Geology of Northwest Libya. Earth Science Society Libya, 1: 275–292.  Google Scholar
	Seilacher, A. 2004a. Constructional “mistakes” in the evolution of blastoid echinoderms. In Heinzeller, T. and Nebelsick, J. H. (eds.). Echinoderms: München. Taylor and Francis, London, 503–508.  Google Scholar
	Seilacher, A. 2004b. Trittbrettfahrer im Muschelkalkmeer. Fossilien 3: 157–160.  Google Scholar
	Seilacher, A. 2004c. Principles of ichnostratigraphy. In Buatois, L. A. and Mángano, M. G. (eds.). Ichnia Trelew, Argentina. Museo Paleontológico Egidio Feruglio, 9–10.  Google Scholar
	Wisshak, M., Volohonsky, E., Seilacher, A. and. Freiwald, A. 2004. A trace fossil assemblage from fluvial Old Red deposits (Wood Bay Formation; Lower to Middle Devonian) of NW Spitsbergen, Svalbard. Lethaia, 37: 149–163.  Google Scholar
	Seilacher, A. and Seilacher, E. 2004. Die Hieroglyphen von Moher Cliffs. Fossilien, 1: 42–45.  Google Scholar
	Seilacher, A. and Hauff, R. B. 2004. Constructional morphology of pelagic crinoids. Palaios, 19: 3–16.  Google Scholar
	Seilacher, A. 2005a. Saccocoma: Plankton-Fischer im Jurameer. Fossilien, 1: 48–52.  Google Scholar
	Seilacher, A. 2005b. Silurian trace fossils from Africa and South America mapping a trans-Gondwanan seaway. Neues Jahrbuch für Geologie und Paläontologie- Monatshefte, 129–141.  Google Scholar
	Seilacher, A. 2005c. Trace fossils as tourist attractions. In Neto de Carvalho, C. (ed.). Cruziana '05: Paleontological Heritage, from Discovery to Recognition; Abstracts from the International Meeting on Paleontological Heritage, Geoconservation and Geotourism. Idanhaa-Nova, Portugal, Centro Cultural Raiano, 43–45.  Google Scholar
	Seilacher, A. 2005d. Pyrit-Sonnen. Globulus, 11: 91–94.  Google Scholar
	Seilacher, A. 2005e. Whale barnacles: Exaptational access to a forbidden paradise. Paleobiology, 31(2)( suppl.): 27–35.  Google Scholar
	Seilacher, A. 2005f. Secondary soft-bottom dwellers: Convergent responses to an evolutionary “mistake.” In Briggs, D.E.G. (ed.). Evolving Form and Function: Fossils and Development. Proceedings of a Symposium Honoring Adolf Seilacher for his Contributions to Paleontology, in Celebration of his 80th Birthday. April 1–2, Peabody Museum of Natural History, Yale University, New Haven, CT, 257–271.  Google Scholar
	Grazhdankin, D. and Seilacher, A. 2005, A re-examination of the Nama-type Vendian organism Rangea schneiderhoehni. Geological Magazine, 142: 571–582.  Google Scholar
	Seilacher, A., Buatois, L.A. and Mángano, M.G. 2005. Trace fossils in the Ediacaran–Cambrian transition: Behavioral diversification, ecological turnover and environmental shift. Palaeogeography, Palaeoclimatology, Palaeoecology, 227: 323–356.  Google Scholar
	Seilacher, A. and MacClintock, C. 2005. Crinoid anchoring strategies for soft-bottom dwelling. Palaois, 20: 224–240.  Google Scholar
	Seilacher, A. 2006. Ein Solnhofner Ammonitenschicksal. Fossilien, 23: 368–370.  Google Scholar
	Seilacher, A. 2007a. Trace Fossil Analysis. Springer, New York, 226 p.  Google Scholar
	Seilacher, A., 2007b. The nature of vendobionts. Geological Society, London, Special Publications, 286: 387–397.  Google Scholar
	Seilacher, A. 2007c. Principles of ichnostratigraphy. In Bromley, R. G., Buatois, L. A., Mángano, G., Genise, J. F. and Melchor, R. N. (eds.). Sediment-Organism Interactions: A Multifaceted Ichnology. Society of Economic Paleontologists and Mineralogists, Special Publication, 88: 53–56.  Google Scholar
	Seilacher, A. 2007d. Fossile Seelilien-Sträuße. Natur und Museum, 137: 159–163.  Google Scholar
	Seilacher, A. 2007e. Evolutionary innovation versus ecological incumbency. In Pudritz, R., Higgs, P. and Stone, J. (eds.). Planetary Systems and the Origins of Life. Cambridge University Press, Cambridge, 193–209.  Google Scholar
	Seilacher, A., Hauff, R.B. and Wolf, M. 2007. Fest verwurzelt in schwimmendem Grund: Treibholz-Seelilien in Lias-Ölschiefern. Fossilien, 6: 349–355.  Google Scholar
	Seilacher, A., Reif, W-E. and Wenk, P. 2007. The parasite connection in ecosystems and macroevolution. Naturwissenschaften, 94: 155–169.  Google Scholar
	Seilacher, A. 2008a. Biomats, biofilms, and bioglue as preservational agents for arthropod trackways. Palaeogeography, Palaeoclimatology, Palaeoecology, 270: 252–257.  Google Scholar
	Seilacher, A. 2008b. Fossil Art. CBM Publishing, Laasby, Denmark, 102 p.  Google Scholar
	Seilacher, A. 2008c. Ediacara - Leben wie auf einem anderen Planeten. In Betz, O. and Köhler, H-R. ( Hrsg.). Die Evolution des Lebendigen, Narr, Francke Attempto Verlag, Tübingen, 97–115.  Google Scholar
	Seilacher, A. 2008d. Ammoniten in Blumen gebettet. Eine besondere Diagenese. Fossilien, 3: 187.  Google Scholar
	Seilacher, A. 2008e. Silurian trace fossils in Al Kufrah Basin: Bracing hot shales and tracking a Trans-Gondwanan Seaway. In Salem, M.J., El-Arnauti, A. and El Sogher Saleh, A. (eds.). The Geology of East Libya, Part III. Earth Science Society of Libya, Tripoli, 189–200.  Google Scholar
	Seilacher, A., Olivero, E.B., Butts, S.H. and Jäger, M. 2008: Soft-bottom tube worms: From irregular to programmed shell growth. Lethaia, 41: 349–365.  Google Scholar
	Volohonsky, E., Wisshak, M., Biomeier, D., Seilacher, A., and Snigirevsky, S. 2008. A new helical trace fossil from the Lower Devonian of Spitsbergen (Svalbard) and its palaeoenvironmental significance. Palaeogeography, Palaeoclimatology, Palaeoecology, 267: 17–20.  Google Scholar
	Rona, P. A., Seilacher, A., de Vargas, C., Gooday, A. J., Bernhard, J. M., Bowser, S. Vetriani, C., Wirsen, C. O., Mullineaux, L., Sherrell, R., Grassle, J. F., Low, S. and Lutz, R. A. 2009. Paleodictyon nodosum: A living fossil on the deep-sea floor. Deep Sea Research Part II: Topical Studies in Oceanography, 56: 1700–1712.  Google Scholar
	Hagadorn, J. W. and Seilacher, A. 2009. Hermit arthropods 500 million years ago? Geology, 37: 295–298.  Google Scholar
	Seilacher, A. and Hagadorn, J. W. 2010. Early molluscan evolution: Evidence from the trace fossil record. Palaois, 25: 565–575.  Google Scholar
	Seilacher, A. 2011. Developmental transformations in Jurassic driftwood crinoids. Swiss Journal of Paleontology, 130: 129–131.  Google Scholar
	Seilacher, A. and Mrinjek, E. 2011. Benkovac Stone (Eocene, Croatia): A deep-sea Plattenkalk? Swiss Geological Society, 104: 159–166.  Google Scholar
	Gingras, M., Hagadorn, J. W., Seilacher, A., Lalonde, S. V., Pecoits, E., Petrash, D. and Konhauser, K. O. 2011. Possible evolution of mobile animals in association with microbial mats. Nature Geoscience, 4: 372–375.  Google Scholar
	Seilacher, A. 2012. New Discoveries of Ordovician Trilobite Burrows in Libya. The Geology of Southern Libya 1. Earth Science Society of Libya, Tripoli, 259–265.  Google Scholar
	Seilacher, A. and Thomas, R.D.K. 2012. Self-organization and emergent individuality of favositid corals adapted to live on soft substrates. Lethaia, 45: 2–13.  Google Scholar
	Seilacher, A. 2013a. Cyclism revisited: extinction and 'Achilles Heels' keep diversification in check on macroevolutionary time scales. Historical Biology, 25: 239–250.  Google Scholar
	Seilacher, A. 2013b. Patterns of macroevolution through the Phanerozoic. Palaeontology, 56: 1273–1283.  Google Scholar
	Seilacher, A. 2013c. Fossil Art (Deutsche Ausgabe). Schweitzerbart, E, Berlin. 97 p.  Google Scholar
	Seilacher, A. and Gishlik 2014. Morphodynamics of Invertebrates. CRC Press, Boca Raton, FL, 531 p.  Google Scholar

Acknowledgments

We would like to thank Dr. Edith Seilacher, Peter Seilacher, and Ulrike Seilacher for providing insights into Dolf's life. Many of the figures in this paper came from Edith or friends of Dolf's, and we thank them all for their permission to use them to celebrate the life and contributions of this amazing scientific paragon. This paper was reviewed by Derek Briggs and Tony Martin, who we thank for their thoughtful comments that improved the manuscript considerably.