Dataset DOI: 10.5061/dryad.4mw6m90rm

Description of the data and file structure

We sampled 62 specimens representing 5 species distributed across the extinct subfamilies Hesperocyoninae and Borophaginae. DMTA analysis was conducted by creating high resolution molds of either the lower second molar or talonid basin of the lower first molar (following Tanis et al. 2018) using polyvinylsiloxane impression material. Molds were filled with a clear epoxy resin and the resulting casts scanned via a Sensofar PLu neox optical profiler at Vanderbilt University. Each scan comprised four adjacent quadrants totaling 206×276 μm² which were analyzed via scale-sensitive fractal analysis software to compile microwear parameters. Median values of DMTA parameters from the four scans were used to represent a given specimen. Analysis of dietary specialization focused on three DMTA parameters with known dietary correlations within carnivorans: anisotropy (epLsar), complexity (Asfc), and textural fill volume (tfv). Quantification of dietary specialization was performed for each species by aggregating DMTA parameters from individual specimens together. Each DMTA parameter was then adjusted with z-score standardization to account for differences in scale without altering distributions. We then used a Bayesian framework to reconstruct 95% probability ellipsoids reflecting a multi-dimensional dietary texture space for each species. Dietary specialization was also assessed via morphological categorization of four anatomical features commonly derived from skeletal and dental elements to identify dietary roles in canids. Specifically, we explored relative blade length of the lower carnassial (RBL), relative surface area for grinding on the upper tooth row (RUGA), the ratio of dentary depth to length (JDJL), and log body mass each compiled from the literature, representing aggregates from throughout their geographic and temporal ranges, not just within the John Day community. first and last appearance dates were estimated from known occurrences to calculate species duration (Foote and Raup 1996; Alroy 2000). Species occurrence data was downloaded from the Paleobiology Database and Miomap Database (last accessed 8 February 2019, using the parameters Taxon Name: ‘Borophagus’, ‘Cynarctoides’, ‘Mesocyon’, ‘Paraenhydrocyon’, ‘Paratomarctus’, ‘Philotrox’, ‘Phlaocyon’, and ‘Rhizocyon’) combined, and cleaned of duplicate records and largely imprecise age brackets. First and last appearance dates were calculated following established Birth-Death Markov chain Monte Carlo procedures via the PyRate package of program Python, running 10 million iterations with the first 200,000 as burn in, thinning by 1,000. Median first and last appearance times were used from the resulting posterior distributions to calculate species duration times. Species duration was compared to each DMTA parameter and morphological trait via Pearson correlation as a broad indicator of relationships between metrics and lineage duration. Species durations were also used to create a series of generalized linear models to assess a relationship between extinction risk, standard ellipsoids (i.e., dietary breadth), and morphological traits. Models were weighted by sample size from the DMTA analysis and were conducted via generalized linear regression. We compared model performance using Akaike’s information criterion adjusted for small sample sizes.

Files and variables

File: Tanis_et_al-Table_S1.csv

Description: Complete list of all specimens analyzed for this project along with general locality information DMTA attribute values for each specimen, standard ellipse volumes (SEV), and dietary categorization. Specimens were sampled from the John Day National Monument Collection (JODA), the University of California Museum of Paleontology (UCMP), and the University of Washington Burke Museum (UWBM). Dental microwear Attributes abbreviations are Asfc (area-scale fractal complexity), epLsar (anisotropy), Tfv (textural fill volume), Smc (scale of maximum complexity), and Ftfv (fine textural fill volume). DMTA attributes do not have units. Missing data is entered as NA.

Variables

• Subfamily

• Species

• Catalog Number: John Day National Monument Collection (JODA), the University of California Museum of Paleontology (UCMP), and the University of Washington Burke Museum (UWBM)

• Formation: Geological units of rock with strata that are associated with distinctive depositional environments. 

• Member: Broad bio-stratigraphic units subdividing geological formations. Here defined by Fisher and Rensberger (1972)

• Section: Designated bio- and litho-stratigrafic subdivisions of geologic members the John Day Formation. 

• Elevation: Designated bio- and litho-stratigrafic subdivisions of geologic sections within parts of the John Day Formation intitally established by Fremd et al. (1994). Letters and numbers (A-M, from older to more recent) are informal subdivisions added over time and roughly corresponding to faunal horizons and later revized with paleomagnetic and Ar/Ar dating.

• mya_base: maximum age estimates in millions of years modeled from U-Pb zircon dates of stratigraphic units via Mohr et al. 2025

• mya_top: minimum age estimates in millions of years modeled from U-Pb zircon dates of stratigraphic units via Mohr et al. 2025

• Tooth facet sampled: l/r (left/right); m2-hypoconid facet of the lower second molar; m1-hypoconid facet of the talonid (t) of the lower first molar

• Asfc: area-scale fractal complexity

• epLsar: anisotropy

• Tfv: textural fill volume

• Smc: scale of maximum complexity

• Ftfv: fine textural fill volume

• Dietary classification: categorization as hypercarnivorous (hyper), mesocarnivorous (meso), or hypocarnivorous (hypo)