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In order to evaluate the rate of publication of papers dealing with ornithopod dinosaurs, the number of papers was tabulated on a per-decade basis from 1820–2010 from the bibliography of The Dinosauria, second edition (Weishampel et al., 2004). Containing 90 published pages of references on all dinosaurian taxa, this book is likely to be comprehensive enough for our current purposes. Because the decade of 2000–2010 was incomplete in that volume, the remainder of this decade was filled in proportionally based on the approximate representation during the first three and one-half years of the decade. That is, the 2000–2010 decadal numbers are projections based on tabulations from the first three and one-half years. Total papers and papers for each research category (see below) were adjusted by multiplying the raw totals for the first three and one-half years of the 2000–2010 decade by a factor of 2.86 to yield a total proportionally equivalent to other decades. This kind of correction was judged preferable to changing data sources (e.g., Web of Science), which would have resulted in an under-sampling of the more obscure literature.

In addition to the total curve, I have attempted to characterize the papers that went into this total by identifying nine categories of research (Table 1.1). I provide general description of these categories, denoted in boldface text, below. These categories were usually assessed by title alone, but occasionally it was necessary to consult the paper itself to determine to which category it belonged. I made no account of footprints and eggshell papers, because it was often impossible to assess affinities of the tracks or shell beyond Dinosauria from the title of the paper.

Table 1.1. Categories of Ornithopod Research Identified in This Survey

General taxonomy

Functional morphology

Phylogeny

Biostratigraphy and taphonomy

Biogeography

Paleoecology

Soft tissue

Growth

Faunistics

General taxonomy refers to those publications announcing new specific or generic taxa, or new taxonomic revisions that do not come under the heading of phylogeny (see below). For example, Gilmore’s (1913) announcement of Thescelosaurus neglectus is here considered a work of general taxonomy.

Functional morphology is the category for papers involving a biomechanical or functional interpretation of an ornithopod anatomical system. An example of a functional morphology study is Alexander’s (1985) work on stance and gait in ornithopods among other dinosaurs.

Phylogeny refers to those studies that attempt to portray the evolutionary history, or phylogeny, of the group. In recent years, these studies have emphasized cladistics in phylogenetic reconstruction (e.g., Prieto-Márquez, 2010), but also include a number of pre-Hennigian analyses (e.g., Galton, 1972).

Biostratigraphy and taphonomy papers involve the geologic disposition of ornithopod specimens, whether within or among rock units. Rogers (1990) provided an example of how bonebed taphonomy can provide evidence for drought-related mortality in dinosaurs that include hadrosaurs.

Biogeography includes studies that examine the geographic distribution of ornithopods either from a dispersal or vicariant perspective, or both. For example, Casanovas et al. (1999) examined the global distribution of lambeosaurine hadrosaurids, whereas Upchurch et al. (2002) considered the full spectrum of controls on dinosaur diversity, including that of ornithopods, as a function of biogeography and biostratigraphy.

Paleoecology papers include those of Carrano et al. (1999) on convergence – or lack thereof – among ornithopods and ungulate mammals, and Varricchio and Horner (1993) on the significance of bonebeds in paleoecological interpretations, and are intended to address the reconstruction of particular taxonomically bound or free ecosystems of the past.

Soft tissue studies have been generally limited to skin impressions. Examples include Osborn (1912) on the “mummy” of Edmontosaurus annectens in the American Museum of Natural History.

Growth includes papers associated with aspects of ontogenetic development. The impact of growth on ornithopod studies is relatively recent. Here I note Dodson (1975) on the taxonomic significance of growth in Lambeosaurus and Corythosaurus, as well as various studies by Horner and colleagues (e.g., Horner et al., 1999, 2000) focused on the cellular basis of bone growth.

Faunistics includes papers whose principal purpose is to establish or review fossil assemblages that include ornithopods. For example, Lapparent (1960) reviewed the dinosaurs, including many ornithopods, from the “Continental intercalaire” of northern Africa.

Usually contributions were entered once in a category. However, a study can contribute here to several categories. For instance, Ostrom (1961) included discussion of general taxonomy, functional morphology, phylogeny, and other subjects in his major review of North American hadrosaurs, and so it was added to each of these categories.