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Fig. 3 in Theropod teeth from the upper Maastrichtian Hell Creek Formation "Sue" Quarry: New morphotypes and faunal comparisons

Fig. 3. Principal components analysis of Richardoestesia teeth from Hell Creek and Lance formations (circles) and dromaeosaurid tooth FMNH PR 2899 from the Sue quarry (cross). Analysis contained variables height, FABL, and denticles/mm. PC 1 ([0.28 FABL]+[0.94 height]-[0.19 denticles/mm]) explained 76.36% of the variance. PC 2 ([0.03 FABL]+[0.18 height]+[0.98 denticles/mm]) explained 22.51% of the variance. PC 3 ([0.96 FABL]-[0.28 height]+[0.02 denticles/mm]) explained 1.13% of the variance.

Fig. 1 in Theropod teeth from the upper Maastrichtian Hell Creek Formation "Sue" Quarry: New morphotypes and faunal comparisons

Fig. 1. Principal components analysis of all teeth from the "Sue" theropod sample, Sankey (2008) tooth database (except Paronychodon and Richardoestesia), and Smith et al. (2005; Deinonychus, Dromaeosaurus, and Troodon). Principal components: (1) ([0.41 FABL]+[0.1 basal width]+[0.90 height]-[0.07 denticles/mm]) explained 77.01% of variance; (2) ([-0.03 FABL]+[0.02 basal width]+[0.09 height]+[1 denticles/mm]) explained 16.58% variance; and (3) ([0.82 FABL]+[0.40 basal width]-[0.41 height]+[0.05 denticles/mm]) 5.00% variance.

Fig. 7 in Theropod teeth from the upper Maastrichtian Hell Creek Formation "Sue" Quarry: New morphotypes and faunal comparisons

Fig. 7. Biplot of dromaeosaurid teeth from "Sue" quarry (dots) and Sankey (2008) database (crosses) measuring height versus denticles/mm. Ovals are the 95% confidence ellipses for each dataset, Sue quarry solid oval and Sankey database in dashed oval. Sue specimens are designated by the specimen number that follows FMNH PR in each instance.

Fig. 6 in Theropod teeth from the upper Maastrichtian Hell Creek Formation "Sue" Quarry: New morphotypes and faunal comparisons

Fig. 6. Principal components analysis of "Sue" quarry dromaeosaurid teeth (dots) in addition to the dromaeosaurid teeth (crosses) included in Sankey (2008). Analysis contained variables height, FABL, and denticles/mm. Basal width was not included because this variable was not included in the Sankey (2008) dataset. PC 1 ([0.38 FABL]+[0 basal width]+[0.90 height]-[0.23 denticles/mm]) explained 89.91% of the variation. PC 2 ([-0.36 FABL]-[0.01 basal width]+[0.38 height]+[0.85 denticles/mm]) explained 6.91% of the variation. PC 3 ([0.85 FABL]-[0.01 basal width]-[0.24 height]+[0.47 denticles/mm]) explained 3.17% of the variation. Ovals are the 95% confidence ellipses for each dataset, "Sue" quarry solid oval and Sankey database in dashed oval. Sue specimens are designated by the specimen number that follows FMNH PR in each instance.

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Fig. 3 in The teeth of the unenlagiine theropod Buitreraptor from the Cretaceous of Patagonia, Argentina, and the unusual dentition of the Gondwanan dromaeosaurids

Fig. 3. In situ teeth of the unenlagiine theropod Buitreraptor gonzalezorum Makovicky, Apesteguía, and Agnolín, 2005 (MPCA 245) from the Upper Cretaceous of La Buitrera, northwestern Río Negro, Argentina. A. Right side of skull, showing the zones of the mandible and maxilla with preserved teeth. B. Second and third tooth preserved in the right mandible (the first tooth is very poorly preserved). In the second tooth the central groove is visible on the lateral side of the crown flanked by shallow ridges. C. Fourth, fifth and sixth teeth preserved in the right mandible. D. First to fourth tooth preserved in the right maxilla. Here the central grooves also are visible on the lateral side of the crowns, like B. E. Left side of the skull, showing the zone with preserved teeth. F. First and second teeth preserved on the left mandible. Also visible are the grooves and the ridges of the lateral sides of the crown. G. Posterior view of F. The arrow shows the broken zone of the mandible, where is visible the root of the second tooth.

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Fig. 5 in The teeth of the unenlagiine theropod Buitreraptor from the Cretaceous of Patagonia, Argentina, and the unusual dentition of the Gondwanan dromaeosaurids

Fig. 5. SEM micrographs of isolated teeth associated with the holotype of the unenlagiine theropod Buitreraptor gonzalezorum Makovicky, Apesteguía, and Agnolín, 2005 from the Upper Cretaceous of La Buitrera, northwestern Río Negro, Argentina. A. Mesio−lateral view of one isolated tooth (MPCA 245 A2). Note the total absence of carinae and denticles on the mesial edge, and the central depression of the lateral side. B. Lateral side of one isolated tooth (MPCA 245 A5). Note the grooves and the ridges located near of the distal edge of the crown, to the left of the image (grooves are marked with arrows).

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Fig. 2 in The teeth of the unenlagiine theropod Buitreraptor from the Cretaceous of Patagonia, Argentina, and the unusual dentition of the Gondwanan dromaeosaurids

Fig. 2. Stratigraphic provenance of unenlagiine taxa, including Buitreraptor. The different taxa silhouettes are in scale each to other.

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Data from: Learning to see the wood for the trees: machine learning, decision trees and the classification of isolated theropod teeth

Taxonomic identification of fossils based on morphometric data traditionally relies on the use of standard linear models to classify such data. Machine learning and decision trees offer powerful alternative approaches to this problem but are not widely used in palaeontology. Here, we apply these techniques to published morphometric data of isolated theropod teeth in order to explore their utility in tackling taxonomic problems. We chose two published datasets consisting of 886 teeth from 14 taxa and 3020 teeth from 17 taxa, respectively, each with five morphometric variables per tooth. We also explored the effects that missing data have on the final classification accuracy. Our results suggest that machine learning and decision trees yield superior classification results over a wide range of data permutations, with decision trees achieving accuracies of 96% in classifying test data in some cases. Missing data or attempts to generate synthetic data to overcome missing data seriously degrade all classifiers predictive accuracy. The results of our analyses also indicate that using ensemble classifiers combining different classification techniques and the examination of posterior probabilities is a useful aid in checking final class assignments. The application of such techniques to isolated theropod teeth demonstrate that simple morphometric data can be used to yield statistically robust taxonomic classifications and that lower classification accuracy is more likely to reflect preservational limitations of the data or poor application of the methods.

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FIGURE A7 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE A7. Strict consensus cladogram of 10 most parsimonious trees recovered from analysis of dentition based characters, with each nodes numbered (see the list of synapomorphies for each clades below). Initial analysis was a New Technology Search using TNT v.1.1 of a data matrix comprising 141 dentition-based characters for one outgroup (Eoraptor lunensis) and 59 nonavian theropod taxa. Tree length = 681 steps; CI = 0.338; RI = 0.56.

FIGURE 7 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE 7. Plots of MAVG versus DAVG of ML 962, ML 327, ML 966 and 19 theropod taxa comprising the data set. For reasons of clarity, only taxa with serration of less than 20 denticles were considered.

FIGURE 4 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE 4. Isolated tooth (ML 966) of an Abelisauridae in lingual (A), mesial (B), labial (C), distal (D), apical (F), basal (G) and linguo-distal (H) views. Mid-crown denticles of the distal carina in lingual view (E, I). Abbreviations: dca, distal carina; esp, enamel spalling; ids, interdenticular sulcus; idsp, interdenticular space; lgr, longitudinal groove; mca, mesial carina; mun, marginal undulation; tun, transversal undulation.

FIGURE 3 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE 3. Isolated tooth (ML 327) of an Abelisauridae in lingual (A), mesial (B), labial (C), distal (D), apical (F), basal (G) and mesio-lingual (H) and labio-distal views. Apical denticles of the distal carina in labial view (E). Abbreviations: dca, distal carina; esp, enamel spalling; ids, interdenticular sulcus; idsp, interdenticular space; lgr, longitudinal groove; mca, mesial carina; tun, transversal undulation; wfa, wear facet.

FIGURE 1 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE 1. Strict consensus cladogram of seven most parsimonious trees recovered from analysis of dentition based characters. Initial analysis was a New Technology Search using TNT v.1.1 of a data matrix comprising 141 dentition-based characters for one outgroup (Eoraptor), 59 nonavian theropod taxa, as well as ML 327, ML 939, ML 962 and ML 966. Tree length = 703 steps; CI = 0.331; RI = 0.564. Bremer support values are in bold and bootstrap values are in italic. For silhouette attribution, see Appendix.

FIGURE A4 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE A4. States of crown structure-based characters. A. Isolated teeth of Baryonyx walkeri (A1, NHM R9951) and Suchomimus tenerensis (A2, MNN G48-9) in lateral view displaying less than ten flutes (char. 108:1) present on both labial and lingual side of the crown (char. 107:2) in those taxa. B. First and second left dentary teeth of Ceratosaurus nasicornis (formerly C. dentisulcatus; UMNH VP 5278 = UUVP 158) in lingual view showing the weak recurvature of these mesialmost crowns (char. 39:1), the untwisted mesial carina (char. 46:0) facing mesio-labially (char. 47:1) and terminating well-above the toothcervix (char. 50:0), and the fluted crown, only present on the lingual side of the tooth (char. 59:1). C. Isolated mesialmost tooth of Masiakasaurus knopfleri (FMNH PR 2696, small tooth) in mesio-lingual view displaying the twisted mesial carina (char. 46:1) extending to the tooth cervix (char. 50:1), as well as the flutes present only on the lingual side of the tooth (char. 59:1). D. First right premaxillary tooth of Proceratosaurus bradleyi (NHM R 4860) in labial view displaying the short longitudinal furrows/striations present at the base of the crown (char. 62:1) and the braided enamel surface texture of the crown (char. 117:1). E. Tenth left maxillary tooth of Herrerasaurus ischigualastensis (PVSJ 407) in lateral view showing the longitudinal furrows/striations present at the base of the crown (char. 62:1; also present on the mesialmost teeth of H. ischigualastensis = Ischisaurus cattoi, MACN 18.060), and the irregular/non-oriented enamel surface texture of the crown (char. 117:0). F. First right premaxillary tooth of Velociraptor mongoliensis (AMNH 6515) in labial view showing the flutes present on the labial side of the crows (char. 59:3). G. Fifth left maxillary tooth of Bambiraptor feinbergi (AMNH 30556) in labial view displaying the wide mesiodistally concave area on the basal part of the crown extending along two-thirds of the crown (char. 73:2) and giving the 8-shaped cross-section of the base crown (char. 72:3), and the two elongated, longitudinal and rounded ridges present on the lingual side of the crown as well (char. 116:2). H. Third right premaxillary tooth of Raptorex kriegsteini (LH PV18) in lingual view showing the two concave areas on the lingual side of the crown and adjacent to both carinae (char. 42:2) and the central and longitudinal ridge on the crown (char. 61:1). I. Sixth and eight left maxillary teeth of Allosaurus fragilis (UMNH VP 5393) in medial view displaying the deep and well delimited unerupted tooth fossa (char. 140:0) and the wide mesiodistally concave area on the basal part of the crown and present on the lingual side of the tooth, giving the bean-shape cross-section of the base crown (char. 72:2) in this specimen (photo courtesy shared by Stephen Brusatte). J. Enamel texture of the sixth right maxillary crown of Majungasaurus crenatissimus (FMNH PR 2278) in lateral view showing the irregular non-oriented enamel surface texture (char. 117:0). K. Enamel texture of the second right maxillary tooth of Acrocanthosaurus atokensis (NCSM 14345) in lateral view showing the regular, oriented braided enamel surface texture of the crown (char. 117:1). L. Enamel texture of an isolated tooth of Baryonyx walkeri (NHM R9951) in lateral view showing the deeply veined enamel surface texture of the crown (char. 117:2), strongly curved basally close to the carina (char. 118:1).

FIGURE 10 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE 10. Isolated tooth (ML 939) of Richardoestesia aff. R. gilmorei in lingual (A), distal (B), labial (C), mesial (D), apical (F) and basal (G) views. Mid-crown denticles of the distal carina in labial (E, I) views, and enamel texture in lingual (H) view. Abbreviations: cs, concave surface; dca, distal carina; ent, enamel texture; esp, enamel spalling; ids, interdenticular sulcus; lad, labial depression; lgr, longitudinal groove.

FIGURE A9a in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE A9a. Strict consensus cladogram of six most parsimonious trees recovered from the analysis of a supermatrix including a dentition-based datamatrix and six recent datasets based on whole theropod skeleton (i.e., Xu et al. 2009; Brusatte et al. 2010; Martinez et al. 2011; Senter 2011; Pol and Rauhut 2012; Carrano et al. 2012). The consensus tree was obtained after the deletion of the wildcard taxa Erectopus and Piatnitzkysaurus. Initial analysis was a Ratchet (Island Hopper) analysis using WinClada 1.00.08 of a supermatrix comprising 1972 characters for one outgroup (Eoraptor) and 57 non-avian theropod taxa. Tree length = 3507 steps; CI = 0.57; RI = 0.64. The same topology was obtained with TNT v.1.1 with a New Technology Search that yielded four MPTs (Tree length = 3529 steps; CI = 0.575; RI = 0.642). The unambiguous and ambiguous dentition based synapomorphies are represented by black and white circles, respectively, and the character number and character state associated with each synapomorphy are above and below the circles, respectively.

FIGURE 2 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE 2. Strict consensus cladogram of 49 most parsimonious trees recovered from analysis of a supermatrix of 1972 discrete characters after the deletion of the two wildcard taxa Erectopus and Piatnitzkysaurus. The supermatrix includes a dentition-based datamatrix of 141 discrete characters and six recent datasets based on whole theropod skeleton (Xu et al. 2009; Brusatte et al. 2010; Martinez et al. 2011; Senter 2011; Pol and Rauhut 2012; Carrano et al. 2012). Initial analysis was a New Technology Search using TNT v.1.1 for one outgroup (Eoraptor), 57 non-avian theropod taxa and ML 327, ML 966, ML 939 (coded as lateral teeth), and ML 962 (coded as a mesialmost tooth). Tree length = 3552 steps; CI = 0.563; RI = 0.628. For silhouette attribution, see Appendix.

FIGURE 9 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE 9. Isolated tooth of Torvosaurus tanneri (ML 962) in labial (A), distal (B), lingual (C), mesial (D) and basal (F) views. Apical denticles of the distal carina in labial view (E). Abbreviations: ce, cervix; dca, distal carina; idsp, interdenticular space; mca, mesial carina.

FIGURE 8 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE 8. Plots of CBR versus DAVG of ML 962, ML 327, ML 966 and 21 theropod taxa comprising the data set. For reasons of clarity, only taxa with serration of less than 22 denticles were considered.

FIGURE A2 in Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth

FIGURE A2. States of dentition-based characters. A. Fourth right premaxillary tooth of Eoraptor lunensis (PVSJ 512) in lateral view lacking a mesial carina (char. 43:0), displaying a concave area present on the labial side of the crown and adjacent to the distal carina (char. 42:1), and having an important constriction between root and crown at both mesial and distal margins (char. 35:1), giving a lanceolate shape to one of the premaxillary teeth (char. 34:0). B. First and second left premaxillary teeth of Dubreuillosaurus valesdunensis (MNHN 1998-13) in anterior (B1) and palatal (B3) views, and second left premaxillary tooth in posterior view (B2) showing a non-twisted (char. 46:0) mesial carina, facing labially (char. 47:1) and terminating wellabove the cervix (char. 50:0), as well as a distal carina facing distally (char. 48:0). The axis passing through both carinae at midcrown in Dubreuillosaurus mesialmost teeth is subparallel to long axis of the skull (char. 49:0). The distal carinae, designated by the green arrows, are centrally positioned on the crown and not displaced labially. C. Premaxillary teeth of Raptorex kriegsteini (LH PV18) in medial (C1) and palatal (C2) views showing the U-shaped outline of mesialmost crowns (char. 41:5), the concave area adjacent to both carinae (char. 42:2), the mesial and distal carinae facing lingually (char. 47:3; char. 48:2), and the axis passing through both carinae at mid-crown in mesialmost teeth that is perpendicular to long axis of skull (char. 49:2). D. Right premaxilla of Majungasaurus crenatissimus (FMNH PR 2100) in palatal view displaying the subrectangular alveoli (char. 13:1), a 'flying-saucer'-shaped outline of the mesialmost teeth (char. 41:2), a concave area present on the lingual side of the crown and adjacent to both carina (char. 42:2), a non-twisted mesial carina (char. 46:0) facing mesially (char. 47:0), a distal carina facing distally (char. 48:0), and an axis passing through both carinae at mid-crown in mesialmost teeth medio-laterally oriented from long axis of skull (char. 49:1). E. First premaxillary tooth of Acrocanthosaurus atokensis (NCSM 14345) in anterior (E1) and posterior (E2) views and premaxillary teeth in palatal view (E3) showing the oval alveoli (char. 13:0), and the mesial carina facing labially (char. 47.1) and terminating well-above the cervix (char. 50:0). Unlike Dubreuillosaurus valesdunensis, the distal carina, pointed by the green arrows, is here strongly displaced labially (char. 48:1). F. Isolated premaxillary crown of Dromaeosaurus albertensis (AMNH 5356) in lingual (F1) and distal (F2) views showing the concave area on the lingual side of the crown and adjacent to the mesial carina only (char. 42:3), and the strongly twisted mesial carina (char. 46:1) terminating at the level of the cervix (char. 50:1). Like Acrocanthosaurus, the distal carina, designated by the green arrow, is strongly displaced labially (char. 48:1). G. Isolated lateral tooth of Carcharodontosaurus saharicus (UC PV6) in lingual (G1), mesial (G2) and labial (G3) views showing the weak constriction between root and crown at the lateral margin (char. 64:2), the weakly sigmoid distal profile of the crown due to the convex apical half of the tooth (char. 68:3), the pronounced and well-visible marginal undulations (char. 112:1) adjacent to both carinae (char. 113:2), and the mesial carina terminating well beneath the cervix (char. 80:2) and extending further basally than the distal carina (char. 79:1; the basal extension of carinae are represented by green bars). H. Lateral teeth of Genyodectes serus (MLP 26-39) in linguodistal (H1) and apical (H2) views showing the concave surface adjacent to the distal carina (char. 71:1) and the wide mesiodistally concave area on the basal part of the labial margin of the crown and giving a bean-shape outline of the cross-section (char. 72:2). I. Tenth left maxillary tooth of Rugops primus (MNN IGU1) in labial views showing the slightly concave, roughly straight distal margin of the crown (char. 68:1), the apically hooked denticles on the distal carina (char. 88:2), and the parabolic margin of apical denticles on the mesial carina (char. 89:1), having a vertical subrectangular shape (char. 91:0). J. Maxillary tooth of Irritator challengeri (SMNS 58022) in labial view showing the convex, almost straight mesial (char. 69:1) and distal (char. 68:2) margins of the crown. K. Mid-crown denticles on the distal carina of the first left maxillary crown of Erectopus superbus (MNHN 2001-4) in lateral view showing the narrow interdenticular space (char. 103:0), and the short interdenticular sulci (char. 105:1) in between the denticles. L. Mid-crown denticles on the distal carina of the height right maxillary tooth of Tyrannosaurus rex (FMNH PR 2081) in laterodistal view showing the broad interdenticular space (char. 103:1) and the welldeveloped interdenticular sulci (char. 105:2) in between the denticles. M. Mid-crown denticles on the distal carina of the third right maxillary tooth of Majungasaurus crenatissimus (FMNH PR 2278) in lateral view showing the apically hooked denticles (char. 88:2), the narrow interdenticular space (char. 103:0), and the well-developed interdenticular sulci (char. 105:2).