DOI: 10.5061/dryad.q8bf1
title: Data from: Latitudinal body size trends in Oligo-Miocene mammals

description: Paleecological data allow not only the study of trends along deep-time
 chronological transects but can also be used to reconstruct ecological
 gradients through time, which can help identify causal factors that may be
 strongly correlated in modern ecosystems. We have applied such an analysis
 to Bergmann’s rule, which posits a causal relationship between temperature
 and body size in mammals. Bergmann’s rule predicts that latitudinal
 gradients should exist during any interval of time, with larger taxa
 toward the poles and smaller taxa toward the equator. It also predicts
 that the strength of these gradients should vary with time, becoming
 weaker during warmer periods and stronger during colder conditions. We
 tested these predictions by reconstructing body-mass trends within canid
 and equid genera at different intervals of the Oligo-Miocene along the
 West Coast of North America. To allow for comparisons with modern taxa,
 body mass was reconstructed along the same transect for modern Canis and
 Odocoileus. Of the 17 fossil genera analyzed, only two showed the expected
 positive relationship with latitude, nor was there consistent evidence for
 a relationship between paleotemperature and body mass. Likewise, the
 strength of body-size gradients does not change predictably with climate
 through time. The evidence for clear gradients is ambiguous even in the
 modern genera analyzed. These results suggest that, counter to Bergmann’s
 rule, temperature alone is not a primary driver of body size and
 underscore the importance of regional-scale paleoecological analyses in
 identifying such drivers.
description: Supplementary Data
 1Supplementary Data 1.
 Raw fossil data. Repository and Specimen indicate the collection in which
 specimen is held and its specimen number. Family, Subfamily, Tribe, Genus,
 and Species indicate taxonomy of the specimen. Site and Site # indicate
 name and locality number of site at which specimen was found. Formation
 indicates geologic formation in which specimen was found. Region and
 Subregion indicate the biological region in which specimen was found
 (after Tedford et al. 2004). Age indicates NALMA subdivision to which
 specimen dates (after Tedford et al. 2004). Latitude indicates decimal
 latitude of site. Source indicates whether specimen was measured by
 authors or collected from published literature, in which case citation of
 paper containing measurement is included. Following columns indicate type
 of measurement made and dental measurements in millimeters: 2LPL = 2nd
 lower premolar length, 3LPL = 3rd lower premolar length, 4LPL = 4th lower
 premolar length, 1LML = 1st lower molar length, 2LML = 2nd lower molar
 length, 3LML = 3rd lower molar length, 2UML = 2nd upper molar length.
 Equid Mass indicates estimated mass of equids in kilograms (using
 equations of Janis 1990).Supplementary Data
 2Supplementary Data 2.
 Raw recent data. Repository and Specimen indicate the collection in which
 specimen is held and its specimen number. Family, Genus, and Species
 indicate taxonomy of the specimen. Latitude indicates decimal latitude of
 site. Mass indicates reported mass of specimen in
 kilograms.