DOI: 10.5061/dryad.h70rxwdqk
title: Data from: Elevated evolutionary rates of biting biomechanics reveal patterns of extraordinary cranio-dental adaptations in some herbivorous dinosaurs

description: Adaptation to specialist ecologies is a key innovation that has
 contributed to the evolutionary success of many vertebrate clades,
 underpinning the acquisition of diverse skull morphologies. Dinosaurs,
 which dominated Mesozoic terrestrial faunas, acquired herbivory multiple
 times, including in clades historically regarded as predominantly
 carnivorous. The evolution of herbivory in theropod dinosaurs is linked to
 drastic changes in dental and craniomandibular functional morphology, yet
 whether such changes occurred more rapidly in herbivorous lineages
 compared to in carnivorous lineages remains untested in a phylogenetic
 framework. Here, we infer rates of phenotypic evolution in relative biting
 edge lengths to test the hypothesis that the acquisition of herbivory is
 associated with rapid changes in jaw biomechanics. We find elevated rates
 of biomechanical evolution in theropods with foreshortened and beaked
 skulls (Oviraptorosauria, Limusaurus), as well as in ceratopsians and
 Diplodocus. A reduced biting edge length and increased jaw efficiency
 unites these high-rate lineages, indicating selection for greater
 efficiency in biting biomechanics. Additionally, we hypothesise that
 extreme ontogenetic changes within species' lifetimes may be behind
 some instances of branch-wise elevated rates. Thus, we show how
 exceptional rates of biomechanical evolution can reveal signatures of
 adaptations within dinosaur lineages and potentially along ontogenetic
 sequences.
description: Data were collected as measurements from published images using
 ImageJ, curated in Excel, wrangled in R and analysed in
 BayesTraits.
description: # Data from: Elevated evolutionary rates of biting biomechanics reveal
 patterns of extraordinary cranio-dental adaptations in some herbivorous
 dinosaurs Linear
 morphometrics taken from images of dinosaur skulls, along with phylogeny
 analysed using variable-rate phylogenetic regression modelling in
 BayesTraits. ## Description of the data and file structure ### ----
 \[\[Data-Primary.xlsx]] ---- Primary dataset file containing raw
 measurements, associated annotations and sources, as well as look-up table
 to match taxa in data and in the tree files. The file contains the
 following tabs: **[Source tab]**\ List of images used for data collection,
 their sources (specimen number, reference), taxonomy, scale info.
 Description of variables * Taxon: Linean binomial * Specimen: specimen
 number or unique identifier * Image file name: the name of the image file
 * Order: taxonomic order * Scale (mm): the scale used to calibrate the
 image file * Scale type: this denotes whether the scale used is a scale
 bar or a morphometric (typically skull length) with a known length **[Data
 tab]** Data for each taxon. Empty cells represent missing data (function
 in for_R tab fills this with NA). Description of variables * L_Sk: linear
 length of the skull (mm) * L_Toothrow: linear length of the biting edge
 length taken as the sum of the lengths along the premaxilla and maxilla
 (mm) * L_Orbit: linear diameter of the orbit (mm) * W_Skull: linear width
 of the skull (mm) * L_DentBattery: linear length of the dental battery if
 present (mm) * d_Bite: linear distance between the jaw joint and the
 posterior-most biting position on the biting edge (mm) * Beak: 0|1 dummy
 variable coding for presence/absence of edentulous beaks **[match_Tree
 tab]** Look up table to match taxon names between morphometric dataset and
 tip labels in the sample of trees of Lloyd et al. (2016). Description of
 variables * Name_in_Data: Taxon name used during data collection *
 Name_in_Tree: Taxon name as it appears on the Lloyd et al. (2016) tree *
 Name_to_Match: This column is used to match the data and the tree. This is
 by default the name in the data but if there is a different corresponding
 name in the tree then that takes prescedence - this is determined by an IF
 function (e.g., =IF(B2="",A2,B2)). * Name_to_Use: This column is
 ultimately the name to be used in the final analysis as it accounts for
 outdated names in the tree. * USE: 0|1 binary coding to denote whether the
 taxon will be used in the final analysis. **[for_R]** Description of
 variables. Cell values are pulled from the Data tab and blank cells are
 filled with NAs. * Name_in_Tree: taxon name that matches to the tip label
 of the Lloyd et al. (2016) trees. * Use: 0|1 binary flag indicating which
 rows to use in the analyses ### ---- \[\[Toothrow linear and arc
 lengths.xlsx]] ---- Supplementary data file to demonstrate the
 relationship between linear biting edge length and the arc length of the
 ventral curvature of the tooth row. The sheet contains a scatterplot with
 a regression line fitted to demonstrate the 1:1 relationship, i.e., there
 is no discernible bias in taking the linear measurement over the arc
 length. Blank cells represent uncollected data and are left blank as the
 graphing function in Excel is incapable of handling NA values. * Taxon:
 Linean binomial * Specimen: specimen number or individual identifier for
 the source of the image * Scale (mm): the known distance the scale was
 calibrated against in ImageJ. * Scale type: type of scale used to
 calibrate image - scale bar (scale bar on image); skull length (where
 scale bar is either absent or unreliable so independent measurement of
 skull length was taken from literature and used to scale image) * L_Pmx:
 linear length of tooth row along premaxilla (mm) * L_Mx: linear length of
 tooth row along maxilla (mm) * L_Tooth: sum of L_Pmx and L_Mx (mm) *
 C_Tooth: arc length of the ventral curvature of the tooth row, taken as
 the sum of a series of linear distances between landmarks placed at the
 tips of the teeth along the tooth row (mm) * log10_L_Tooth: log10
 transformed L_Tooth * log10_C_Tooth: log10 transformed C_Tooth \--NOTE:
 L_Pmx, L_Mx, L_Tooth and C_Tooth were remeasured for a subset of the
 theropod dinosaurs (those with tooth rows instead of beaks) by MS for the
 sole purpose of comparing measurement discrepancies between linear biting
 edge length (L_Tooth) and arc lengths of the ventral curvature of the
 tooth row (C_Tooth). The original data used in the main analyses were
 measured by CK. Slight variation in measurement owe to differences between
 MS and CK. log10_C_Tooth was plotted against log10_L_Tooth and a trend
 line was fitted. The slope of 1.015 is indicative of an isometric
 relationshp between log10_C_Tooth and log10_L_Tooth, meaning that the two
 measurement of tooth row lengths scale 1:1, which the intercept of 0.0127
 indicates that log10_C_Tooth is on average 1.03 times larger than
 log10_L_Tooth, i.e., roughly 3% over-estimate the latter. This discrepancy
 is minimal and within margin of error, particularly with measurements
 dealing with fossil organisms. ### ---- \[\[data.txt]] ---- This file is
 the data file that was fed into BayesTraits. * Taxon: Linnean binomial *
 Order: Grouping variable denoting one of three dinosaurian clades,
 Theropoda, Sauropodomorpha, and Ornithischia * L_Sk: linear length of the
 skull (mm) * L_Pmx: linear length of tooth row along maxilla (mm) *
 L_Bite: linear length of the biting edge length taken as the sum of the
 lengths along the premaxilla and maxilla (mm) * d_Bite: linear distance
 between the jaw joint and the posterior-most biting position on the biting
 edge (mm) * L_Orbit: linear diameter of the orbit (mm) * Beak: 0|1 dummy
 variable coding for presence/absence of edentulous beaks * logLSk: log10
 transformed L_Sk * logLPmx: log10 transformed L_Pmx * logLBite: log10
 transformed L_Bite * logdBite: log10 transformed d_Bite * logLOrbit: log10
 transformed L_Orbit ### ---- \[\[trees.nex]] ---- Nexus file containing
 100 time-scaled trees from Lloyd et al. 2016 - this is also used as input
 for BayesTraits. ## Sharing/Access information Data was derived from the
 following sources: * Sources are listed in Data-Primary.xlsx ##
 Code/Software BayesTraits V4: