Stromatoporoidea, 1926-2000

Journal of Paleontology, Nov 2001 by Stock, Carl W

ABSTRACT-The history of research on the "true" stromatoporoids, a presumably monophyletic group of sponges that occurred from the Ordovician through the Devonian, is examined in detail. Stromatoporoid published research is summarized in five categories: quantity of publication; biological affinities; systematics; skeletal microstructure; and paleoecology. Quantity of publication is measured from each of the 75 years. Moderate levels of publication in the late 1920s and 1930s declined in the early 1940s, and were reduced to zero for four years due to the impact of World War II. Levels similar to that of the 1930s returned in the 1950s, after which there was an overall increase until the mid-1980s, when levels began a decrease that persists today. The proportion of research on paleoecology has increased as research on systematics decreased through time. Post-Devonian forms assigned to the stromatoporoids are a polyphyletic grouping of several apparently unrelated taxa, possibly representing both Porifera and Cnidaria. Publications on the post-Devonian "stromatoporoids" amount to less than one-third that on the true stromatoporoids during the same 75 years.

INTRODUCTION

THE TERM stromatoporoid" has been assigned to various taxa ranging in age from the Cambrian through the Tertiary. For the purposes of this paper, only those organisms that have been demonstrated to have a phyletic connection with Stromatopora are considered to be true stromatoporoids; these occur from the Lower Ordovician through the Upper Devonian. Cambrian socalled stromatoporoids are now regarded as archaeocyaths (Zhuravlev et al., 1994). Those fossils found in Carboniferous through Tertiary rocks that have been called stromatoporoids, represent a polyphyletic grouping of several kinds of organisms that have evolved by convergence on the stromatoporoid morphology, the so-called "stromatoporoid-grade" of organization of Wood (1990); these will be dealt with in greater detail below.

QUANTITY OF RESEARCH

It is assumed that the number of publications is the best indicator of the intensity of research being done on a particular topic, Therefore, simple counts of publications per year for the past 75 years will be used an indicator of the amount of research being conducted at any particular time (Fig. 1). The 734 papers included here deal with the taxonomy, systematics, biological affinities, paleoecology, and paleobiogeography of the stromatoporoids. A qualifying publication must be a journal article, monograph, book, or book chapter. No abstracts, museum catalogs, book reviews, theses, nor dissertations have been included. Also not included are publications in which the presence of stromatoporoids in a reef or particular stratigraphic unit is simply listed or briefly mentioned.

The history of the study of stromatoporoids from 1926 to 2000 can be divided into three episodes of unequal length. Episode 1 (1927-1942) is characterized by relatively few publications, with peaks at seven (1931) and eight (1937) in single years. The most prolific author of this episode is Riabinin (e.g., 1929, 1932, 1937, 1939, 1941) with 10 publications. The dominant topic of Episode 1 is systematics. Next came what can be thought of as the "World War II hiatus," (1943-1946) during which nothing on stromatoporoids was published.

An overall increase in the rate of publication, culminating with 32 in 1984, characterizes Episode 2 (1947-1984). The number of publications dealing with the paleoecology (see below) and biological affinity of stromatoporoids increased during this time. Bogoyavlenskaya (e.g., 1965a, 1965b, 1969a, 1969b, 1971, 1972a, 1973, 1977b, 1981, 1982, 1984) is the most prolific author of Episode 2 with 36 publications.

Since 1984 the rate of publication on stromatoporoids has declined; this constitutes Episode 3 (1985-2000). Systematics and paleoecology accounted for the majority of publications. The most prolific author of this episode is Steam (e.g., 1990, 1992, 1993, 1997; Steam and Mah, 1987; Webby et al., 1993; Steam and Pickett, 1994; Prosh and Steam, 1996; Steam et al., 1999) with 22 publications.

The number of publications alone does not always represent the contributions of monographs, which in many cases contain a great deal information on a number of subjects. In particular, many include both systematics and paleoecology. Some examples of such monographs include those by Riabinin (1951, 1953), Nestor (1964, 1966, 1976), Mori (1968, 1970), Bogoyavlenskaya (1973), Bol'shakova (1973), and Stock (1979) on the Silurian, and Parks (1936), Lecompte (1951, 1952a), Galloway and St. Jean (1957), Kazmierczak (1971), Zukalova (1971), Khromych (1974, 1976), Yang and Dong (1979), Fagerstrom (1982), Cockbain (1984), Mistiaen (1985), Khromych and Nguyen (1988), and Prosh and Steam (1996) on the Devonian. Yavorsky's (1955, 1957, 1961, 1963, 1967) monographs on stromatoporoids of the Ordovician through Devonian of the USSR also deserve mention. Individual summary articles and monographs that have been cited, and probably will be cited, often by many workers include those by Kahn (1927, 1939), Lecompte (1956), Galloway (1957), Flagel and Flugel-Kahler (1968), Webby (1979, 1986, 1993), Steam (1980), Bogoyavlenskaya and Khromych (1985), and Steam et al. (1999).