Determining which biological traits affect taxonomic durations is critical for explaining macroevolutionary patterns. Two approaches are commonly used to investigate the associations between traits and durations and/or extinction and origination rates: analyses of taxonomic occurrence patterns in the fossil record and comparative phylogenetic analyses, predominantly of extant taxa. By capitalizing upon the empirical record of past extinctions, paleontological data avoid some of the limitations of existing methods for inferring extinction and origination rates from molecular phylogenies. However, most paleontological studies of extinction selectivity have ignored phylogenetic relationships because there is a dearth of phylogenetic hypotheses for diverse non-vertebrate higher taxa in the fossil record. This omission inflates the degrees of freedom in statistical analyses and leaves open the possibility that observed associations are indirect, reflecting shared evolutionary history rather than the direct influence of particular traits on durations. Here we investigate global patterns of extinction selectivity in Devonian terebratulide brachiopods and compare the results of taxonomic vs. phylogenetic approaches. Regression models that assume independence among taxa provide support for a positive association between geographic range size and genus duration but do not indicate an association between body size and genus duration. Brownian motion models of trait evolution identify significant similarities in body size, range size, and duration among closely related terebratulide genera. We use phylogenetic regression to account for shared evolutionary history and find support for a significant positive association between range size and duration among terebratulides that is also phylogenetically structured. The estimated range size–duration relationship is moderately weaker in the phylogenetic analysis due to the down-weighting of closely related genera that were both broadly distributed and long lived; however, this change in slope is not statistically significant. These results provide evidence for the phylogenetic conservatism of organismal and emergent traits, yet also the general phylogenetic independence of the relationship between range size and duration.
Terebratulide body size measurements from museum specimens
Data on the maximum body size of terebratulide genera collected via measurements of museum specimens. More than 2000 intact specimens of Paleozoic terebratulides were measured in the collections at the Natural History Museum (London), the National Museum of Natural History (Washington, D.C.), and the Yale Peabody Museum (New Haven, Conn.). Each specimen was aligned and photographed from two orthogonal angles, one angle representing the commissure margin and the other representing the “profile,” or the side view. 101 equally spaced coordinates were sampled around the commissure margin, using the software program tpsDig v. 1.4 written by James Rohlf and then scaled to millimeters. Centroid size for was then calculated each individual, using the coordinates sampled from the commissure view. Each genus is represented by the individual specimen with the largest measured centroid size. Centroid sizes were gathered for 28 Devonian genera, with the median number of specimens measured per genus equal to 5.5 (interquartile range was 2 to 18.25 specimens).
Terebratulide body size measurements from figured specimens
Data on the maximum body size of terebratulide genera collected from figured specimens in the Treatise on Invertebrate Paleontology (Kaesler 2000). Linear measurements of shell width and length were gathered, as well as shell height wherever possible. For genera comprising two or more species, genus body size was calculated as the geometric mean of the holotype specimen for each species. If the holotype was not figured for a species, the paratype, neotype, or best-resolution illustration was used, in that order. Length: shell length (in mm) - beak to commissure; Width: shell width (in mm) - parallel to hinge; Height: shell height (in mm) - perpendicular to the other two axes; Area: product of shell length and width, in log10 mm^2; Volume: product of shell length, width, and height, in log10 mm^3; Figure: figure number of the measured illustration in the Treatise on Invertebrate Paleontology; Figure_part: figure part in the Treatise (required to get the exact specimen measured); Founder: this is the authority for the species as reported in the Treatise; Year: this is the year in which the measured species was described.
The geographic occurrences of Devonian terebratulide genera. These occurrence data were compiled previously in an exhaustive search of the published literature for a study of Paleozoic terebratulide latitudinal diversity gradients (Fitzgerald and Carlson 2006). The data set consists of 476 occurrences, resolved to 5 degree paleolatitudinal bins, ranging from 85 degrees S to 45 degrees N.
Terebratulide data for extinction selectivity analyses
File contains data used in Devonian terebratulide extinction selectivity analyses. "Duration" is the stratigraphic range of each terebratulide genus in millions of years. "Singleton" identifies genera known from only a single geological stage. "Raw_Cumulative_Latitudinal_Range_Size" is the cumulative latitudinal range size of each genus over its duration. "Standardized_Cumulative_Latitudinal_Range_Size" is the cumulative latitudinal range size of each genus scaled to the maximum range size possible over its duration. "Raw_Max_Latitudinal_Range_in_a_Stage" is the maximum latitudinal range of each genus in a given geological stage. "Standardized_Max_Latitudinal_Range_in_a_Stage" is the maximum latitudinal range of each genus in a geological stage scaled to the maximum possible in that stage. "Body_Size_Area" is the product of shell length and width, in log10 mm^2. "Body_Size_Volume" is the product of shell length, width, and height, in log10 mm^3.
Terebratulide stratigrapihc ranges
Genus durations calculated from the observed first and last occurrence data from the revised brachiopod Treatise on Invertebrate Paleontology (Curry and Brunton 2007), with genera assumed to range from the base of the stage in which they first occurred to the top of the stage in which they last occurred. Ages of stage boundaries are from the revised Devonian timescale of Ogg et al. (2009).
Terebratulide temporally-calibrated phylogeny
Temporally-calibrated phylogenetic hypothesis for Devonian terebratulide genera using the strict consensus of 71 phylogenetic trees reported by Carlson and Fitzgerald (2008). Note that tips in this phylogeny correspond to the first occurrences of terebratulide genera, not last occurrences, so as to reduce any circularity when the tree was used for comparative analyses that included genus duration. Please refer to the article for additional details regarding the phylogeny and temporal calibration.