Journal of Vertebrate Paleontology 30(5):1478–1485, September 2010 © 2010 by the Society of Vertebrate Paleontology ARTICLE NAMING DINOSAUR SPECIES: THE PERFORMANCE OF PROLIFIC AUTHORS MICHAEL J. BENTON Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, U.K., [email protected] ABSTRACT—Many current debates about biodiversity and large-scale evolution have identified the need for comprehen- sive species inventories. Such species lists may be incomplete because more collecting is needed, or because of errors by systematists. Empirical studies show that error rates are high, as much as 30–50% for many living and fossil groups. A clear requirement is skilled systematists, and more of them; but who does the best work? An empirical investigation of the 321 authors who named all 1400 species of dinosaurs since 1824 shows that prolific authors do worse than authors who name only a few dinosaurs, and the key difference is between the 147 authors who named only one species, and the 174 who named two or more. The most prolific author was Othniel Marsh, who named 98 species of dinosaurs (including 80 non-avian dinosaurs and 18 Mesozoic birds), but only 35 (36%) of his names are currently regarded as valid. The poor showing by prolific authors is not a result of their working at different times over the last two centuries, nor on dinosaurs of a particular age, body size, or quality class, nor that their work has been over-revised, but most likely because many prolific authors of dinosaur species names have been too interested in splitting species. Current tougher refereeing standards and international communication should continue to improve standards in naming new taxa. INTRODUCTION For fossil brachiopods, Grant (1980) noted that Gustav Arthur Cooper of the Smithsonian Institution had named, or co-named, Correct species lists are crucial for good studies of evolution- 442 (13%) of the then-known 3300 genera. In the case of di- ary biology, ecology, paleontology, and biodiversity conserva- nosaurs, three researchers, Othniel C. Marsh, Friedrich von tion (Gaston and Mound, 1993; Purvis and Hector, 2000; Wil- Huene, and Edward D. Cope, dominated the field for a long son, 2003; Isaac and Purvis, 2004). The problem of error in such time; they were responsible respectively for 98, 71, and 64 species lists has long been recognized (May, 1990; Wilson, 1992; Gas- names (Fig. 1). By 1900, Marsh and Cope together had named ton and Mound, 1993), and most of that error has been as- 169 (47%) of the 362 dinosaur species names then in existence. cribed to synonymy, the act of naming a species (or other taxon) Now, with a further century of study, the proportion of the that has already been named. Such errors are unavoidable in total represented by their names has fallen to 12% (Benton, view of the vast diversity of life, variability between genders, 2008b). growth stages, and geographic populations, and the diversity of Such prolific authors would be expected to have a lifetime of languages and countries in which taxonomists work. Errors are expertise, and so ought to have an exemplary record in decision- generally identified when synoptic revisions are done at a later making. Having seen more material, often around the world, date. and devoting themselves solely to the task, they should have a Species lists depend on the accumulated labors of many work- sure touch in recognizing synonymy and in determining when a ers over the decades, and yet certain individual systematists have new find is truly a new species. Other authors, who may name tended to dominate each group of organisms. These ‘prolific au- just one or two new species in their careers, might be expected thors’ are researchers who are and were motivated to explore a to make mistakes more often. Indeed, for Thysanoptera, Gas- particular taxonomic group thoroughly. In some cases, their cho- ton and Mound (1993) found slightly mixed evidence, but the sen group is so obscure that they may labor alone in the world, most prolific author had an invalidation rate of only 8.5%, and without a living systematist with whom to discuss their work; for they made a policy recommendation, “that it would be more other organismal groups, there may be merely a handful of ex- cost effective to increase the level of support to particularly perts scattered widely around the world. Biologists and paleon- productive individuals rather than increase the total number of tologists in the great museums of the world have had the re- taxonomists” (Gaston and Mound, 1993: 142). sources to collect and curate material and to produce hefty mono- The purpose of this study is to scrutinize the work of prolific di- graphs in which the systematics of major groups are revised, and nosaurian systematists, and to determine whether they worked in many new species may be named. Less prolific authors range different ways from their less active colleagues, and whether their from those who published very little of any kind, and yet named work was better as a result of accumulated expertise, or whether one or two species, to those with distinguished research careers in some might have named many species because they were moti- biology or paleontology, but who did not include naming species vated in other ways. The measures of ‘quality’ are the survival as a major activity. of their names to the present day, and the quality of the speci- Gaston and Mound (1993) noted that almost half the 6112 mens they used, ranging from isolated scraps to whole skeletons. species of Thysanoptera (thrips) named from 1901 to 1993 were Of course, it may be that dinosaurian systematists are a special authored by four people, and one of these was responsible breed, subject to different pressures and temptations than sys- for 1065 names. The same is true for caecilians (limbless am- tematists of other groups; further, working on the systematics of a phibians), whose species list up to 1970 was dominated by one fossil group may lead to different behavior or different outcomes researcher, Edward H. Taylor, who described 40 (25%) of from working on extant taxa. the then-known 157 species (Nussbaum and Wilkinson, 1989). 1478 BENTON—NAMING DINOSAURS 1479 FIGURE 1. Portraits of the three most pro- lific authors of new dinosaur (and Mesozoic bird) names: A, Othniel C. Marsh (1831–1899), who named 98 species; B, Friedrich von Huene (1875–1969), who named 71 species; and C, Edward D. Cope (1840–1897), who named 64 species. (Marsh and Cope portraits from copyright-free sources; Huene portrait from Collections and Museum, Institute of Geo- sciences, University of Tubingen.)¨ SYSTEMATIC PRACTICE AND ERROR yet only 230 of these (16.4%) are synonyms, 340 (24.3%) are des- ignated nomen dubium, 47 (3.4%) are designated nomen nudum, Species lists may grow and shrink for many reasons. Hard- and 58 (4.1%) are not dinosaurs. [Nomina dubia are based on un- est to document is the constant tension between ‘splitters’ diagnostic or incomplete type materials and nomina nuda have and ‘lumpers,’ those systematists who divide species finely or no designated type material.] So, of invalid dinosaurian species, coarsely. Splitters may recognize each population group or ge- twice as many have been invalidated for reasons other than syn- ographic variant as a species, whereas lumpers might call such onymy. forms varieties or subspecies of a larger species. There are no rules for determining the level at which varieties, subspecies, METHODS species, and genera ought to be discriminated, and such debates are even trickier in dealing with fossil species, where generally the The database (http://paleo.gly.bris.ac.uk/dinosaur/dinospecies only evidence is characters of hard tissues of skeletons or shells. .xls) is a complete listing of all 1400 dinosaurian species names The current view of validity of species names probably depends compiled in order of publication, from the 1820s to the end of as much on the quality of the earlier work as on the quality of re- 2004. The primary source was Weishampel et al. (2004), a com- vision. If a lumper reviews a splitter’s work, many species will pilation of systematic chapters on all dinosaurian groups, but the be moved to synonymy; in the reverse case, it is likely that most listing was enhanced by adding papers to the end of 2004, but older species names will survive, and more will be added. In cases importantly by tracking each name through time to document in- where interest is sustained and broad, such as in dinosaur sys- validations and revalidations: this required a thorough reading of tematics, revisions happen every few years or decades, and the nearly every taxonomic paper on dinosaurs, from 1824 to 2004 risk of bias by a single active author or reviser is reduced. Species (Benton, 2008a, 2008b). Data were also recorded on the date of may survive scrutiny throughout, others may be identified as er- naming, authors, geographic location (country, continent), geo- roneous early on and remain in that state, whereas yet others may logical age (period, epoch, stage, geological formation), size (to- be identified as erroneous by one reviser, and then may be resus- tal body length, arbitrarily divided into small [up to 2 m long], citated by a later reviser, and so come in and out of validity many medium [2.01–5 m long], large [5.01–10 m long], very large [more times. Alroy (2002, 2003) described a ‘flux ratio’ method to docu- than 10.01 m long]), validity (whether currently valid or not), and ment the fluid nature of species lists through time. He noted that, quality of the type specimen (isolated remains, a skull, several despite the constant flux of names, most remain in the state (valid skulls, a skeleton, several skeleton).