DOI: 10.5061/dryad.2547d7x3j
title: Taxonomic utility of isolated ankylosaurian dinosaur teeth using traditional and geometric morphometrics with implications for ankylosaur palaeoecology

description: The presence of a basal cingulum, fluting, and overall size have been used
 to differentiate nodosaurid and ankylosaurid teeth for decades. The
 taxonomic utility of tooth morphology in ankylosaurs, however, has not
 been quantitatively tested. Additionally, new phylogenetic hypotheses
 recognize four ankylosaur families (Panoplosauridae, Polacanthidae,
 Struthiosauridae, and Ankylosauridae), rather than the traditional
 nodosaurid-ankylosaurid dichotomy. Understanding ankylosaur tooth
 variation could better help identify taxa with ambiguous phylogenetic
 affinities or allow isolated teeth to test palaeoecological questions like
 a potential extirpation of mid Cretaceous ankylosaurids from Laramidia. We
 analyzed a large sample of ankylosaur teeth using traditional and
 geometric morphometrics and investigated the utility of size and the
 presence of a cingulum and fluting for differentiating ankylosaur teeth.
 Morphometric analyses show that ‘nodosaurids’ had the greatest variation
 in tooth shape and size. Panoplosauridae and Struthiosauridae accounts for
 a large amount of ‘nodosaurid’ variation, whereas basal ankylosaurs,
 Polacanthidae, and Ankylosauridae share a similar restricted morphospace.
 Teeth with a crown base length or height over 10 mm are only found in
 panoplosaurids, struthiosaurids, and Peloroplites, but smaller sizes are
 found in all clades. A basal cingulum and fluting are associated with
 Ankylosauridae and Panoplosauridae. Linear discriminant analyses could
 only accurately identify between 50-75% of the teeth in our sample, thus
 they should be used in conjunction with size and discrete traits when
 identifying isolated teeth. With these findings, caution should be used
 when attempting to use isolated ankylosaur teeth in broader
 palaeoecological questions and reclassification of museum collections
 should be undertaken.
description: # Taxonomic utility of isolated ankylosaurian dinosaur teeth using
 traditional and geometric morphometrics with implications for ankylosaur
 palaeoecology Dataset DOI:
 [10.5061/dryad.2547d7x3j](10.5061/dryad.2547d7x3j) ## Description of the
 data and file structure We have included the raw dataset, as well as the
 tooth outline data and R code needed to replicate PCAs of traditional and
 outline morphometrics for leaf-shaped ornithischian teeth. We have data on
 over 300 ornithischian teeth associated or *in situ* with skulls of known
 species. We indicate whether the data and tooth images were collected in
 person by the authors, or from literature. We include the R code and tooth
 outlines for both the labial and lingual views of the teeth. We also
 include complementary figures to the plots in the main text.
 "Supplemental 7.docx" indicates how principal compenents one and
 two contribute to the shapes in the morphospaces in our PCAs. We conducted
 linear regressions and residuals for the crown height and crown base
 lenght biplot in "Supplemental 8.docx." We plot our outline
 analysis PCA and LDA with *Animantarx* in its alternate location as basal
 ankylosaur in "Supplemental 9.pdf" ### Files and variables ####
 File: Supplemental_1.csv **Description:** This file is a summary of the
 teeth used in our analyses, indicating how many teeth come from each
 specimen, specimen age, whether teeth are associated or *in situ*, and
 type status. * *Specimen number*: Specimen number from institution *
 *Taxon*: Currently accepted specimen taxon * *Coombs (1978) family*:
  Specimen family identification using the Coombs (1978) classification *
 *Raven et al (2023) family*: Specimen family identification using the
 Raven et al. (2023) classification * *#of teeth used*: How many teeth are
 used from each specimen * *Formation*: Geological formation * *Age*:
 Geological age of specimen * *Type status*: Type status of the specimen,
 n/a means no designated type status * *Teeth in situ or associated*:
 Whether the specimens are in situ in a skull or associated #### File:
 Supplemental_2.csv **Description:** This file contains all of the
 tradtional morphometric measurements and discrete chracter scorings for
 all of the teeth used in our analyses. * *Specimen number*: Specimen
 number from institution * *Coombs (1978) family*:  Specimen family
 identification using the Coombs (1978) classification * *Raven et al
 (2023) family*: Specimen family identification using the Raven et al.
 (2023) classification * *Species*: Currently assigned species of specimens
 * *Formation*: Geological formation * *Image source*: Image sources for
 outline geoemtric morphometric analyses * *Age citation*: Literature
 source for specimen age * *Age*: Geological age of specimen * *Isolated or
 associated*: Whether the specimens are in situ in a skull or associated *
 *Basal cingulum?*: Presence or absence of basal cingulum (y means present,
 n means absent, NA means no data - tooth is too worn to tell or difficult
 to tell from images) * *Fluting?:* Presence or absence of fluting (y means
 present, n means absent, NA means no data - tooth is too worn to tell or
 difficult to tell from images) * *Root?*: Presence or absence of root (y
 means present, n means absent, NA means no data - tooth is too worn to
 tell or difficult to tell from images) * *CH*: Tooth crown height (mm),
  NA means no data - tooth is too worn or broken to tell * *CBL*: Tooth
 crown base length (mm),  NA means no data - tooth is too worn or broken to
 tell * *NL*: Tooth neck length (mm),  NA means no data - tooth is too worn
 or broken to tell * *AL*: Tooth apical length (mm),  NA means no data -
 tooth is too worn or broken to tell * *MCL*: Tooth mesial crown length
 (mm),  NA means no data - tooth is too worn or broken to tell * *DCL*:
 Tooth distal crown length (mm),  NA means no data - tooth is too worn or
 broken to tell * *MDC*: Tooth mesial denticle count,  NA means no data -
 tooth is too worn or broken to tell * *DDC*: Tooth distal denticle count,
  NA means no data - tooth is too worn or broken to tell * *MDH*: Tooth
 mesial denticle height (mm),  NA means no data - tooth is too worn or
 broken to tell * *MDL*: Tooth mesdial denticle length (mm),  NA means no
 data - tooth is too worn or broken to tell * *DDH:* Tooth distal denticle
 height (mm),  NA means no data - tooth is too worn or broken to tell *
 *DDL*: Tooth distal denticle length (mm),  NA means no data - tooth is too
 worn or broken to tell * *CA*: Tooth crown angle (degrees),  NA means no
 data - tooth is too worn or broken to tell #### **File:
 Supplemental_3.txt** **Description:** This file is the annotated R code
 for labial tooth outlines. #### File: Supplemental_4.txt
 **Description:** This file is the annotated R code for lingual tooth
 outlines #### File: Supplemental_5.zip **Description:** This .zip file
 contains a folder with all of the 161 labial tooth outlines and
 "labial_outlines.csv" needed for running the labial R code to
 replicate our PCAs.  #### File: Supplemental_6.zip **Description:** This
 .zip file contains a folder with all of the 189 lingual tooth outlines and
 "lingual_outlines.csv" needed for running the lingual R code to
 replicate our PCAs.  #### File: Supplemental_7.pdf **Description:** This
 file contains figures that describe how principal components one and two
 contribute to shape in the morphospaces of each of our PCA plots. ####
 File: Supplemental_8.pdf **Description:** This file contains a linear
 regression and plots of residuals for our crown height and crown base
 length tooth size biplot. #### File: Supplemental_9.pdf
 **Description:** This file contains an outline PCA and LDA with
 *Animantarx* plotted as its alternate family identification as a basal
 ankylosaur. ## Code/software "Supplemental 3.docx" and
 "Supplemental 4.docx" contain our R script to be run with the
 outline and csv files in "Supplemental 5. zip" and
 "Supplemental 6.zip" ###### *Language and Environment* RStudio
 ###### *Version* 2023.09.1+494 ***Dependencies*** tidyverse Momocs shapes
 ade4 ## Version changes: **July 14, 2025**: References section added to
 Supplemental_1.csv