ELECTRONIC SUPPLEMENTARY MATERIAL FOR

ELECTRONIC SUPPLEMENTARY MATERIAL FOR:

Craniofacial form and function in Metriorhynchidae (Crocodylomorpha:

Thalattosuchia): modelling phenotypic evolution with maximum likelihood methods

Mark T. Young

1,*

, Mark A. Bell

2

, Stephen L. Brusatte

3,4

1

School of Geosciences, Crew Building, The King’s Buildings, University of Edinburgh,

West Mains Road, Edinburgh, EH9 3JW, UK

2

Department of Geographical and Earth Sciences, Gregory Building, Lilybank Gardens,

University of Glasgow, Glasgow, G12 8QQ, UK

3

Division of Paleontology, American Museum of Natural History, Central Park West at 79 th

Street, New York, NY 10024, USA

4 Department of Earth and Environmental Sciences, Columbia University, New York, NY,

USA

1) Additional Analyses: Data Sensitivity and Robustness

2) Systematic Palaeontology: Clade Definitions and Diagnoses

3) Supplementary References

4) Form and Function Raw Data

1) Additional Analyses: Data Sensitivity and Robustness

Our maximum likelihood analyses are based on the taxonomic sample and phylogenetic framework that is currently available. It is worthwhile, therefore, to address how alternative phylogenetic topologies and subsampled taxonomic samples (the latter simulating a less complete fossil record than is currently known) may affect our analyses.

Here, we provide sensitivity analyses in which we re-run our maximum likelihood analyses to determine how robust our results may be to different phylogenetic topologies and a less complete fossil record. If the same general results are recovered as in our full analysis, then the results reported in the main text of the paper can be considered robust. It is always possible, of course, that future fossil discoveries (which would increase the taxonomic sample, add to and perhaps change the phylogeny, and provide additional morphological and functional data) may lead to different results, but it is not possible to confidently predict the affects of discoveries that are yet to be made.

A. Alternate topology

An alternate topology of Metriorhynchidae is presented in the supplementary material of Young et al . (in press). This topology is based on a second phylogenetic analysis, which is a modified version of the primary phylogenetic analysis reported by that paper, but in which all multistate characters were treated as ordered (i.e., representing a transformational sequence). This analysis resulted in a similar topology as the primary phylogenetic analysis; in fact, the cladograms are very similar, except that the second phylogenetic analysis places

Dakosaurus manselii as the sister taxon to the clade of Geosaurus + Dakosaurus and not as the basal-most species of Dakosaurus . The fact that the two analyses return such similar results supports the robusticity of our current knowledge of metriorhynchid phylogeny, so the affects of alternative topologies on the maximum likelihood analysis presented herein may

not be a major concern. However, we have re-run our maximum likelihood analyses using the second topology, which gives the same general results (compare Table 1 to Table S1). Most importantly, analyses using both the primary and secondary topologies find the same models of form and functional evolution to be most likely in each scenario examined (Brownian motion most likely for RW1 and RW2 for Metriorhynchidae and RW1, RW2, and von Mises for Geosaurinae; directional trend found to be most likely for von Mises for

Metriorhynchidae and Metriorhynchinae; stasis found to be most likely for RW1 and RW2 for Metriorhynchinae). Therefore, our results are robust to realistic topological differences in current studies of metriorhynchid phylogeny.

Table S1: AICc weights for the four maximum likelihood models of Metriorhynchidae and its two subfamilies, with the most likely model highlighted in bold.

Taxon Metric BM DT OU Stasis

Relative warp 1 0.671 0.173 0.156 <0.0001

Metriorhynchidae Relative warp 2 0.407 0.153 0.186 0.255 von Mises stress 0.283 0.699 0.045 0.002

Relative warp 1 0.168 0.113 0.060 0.659

Metriorhynchinae Relative warp 2 0.088 <0.0001 0.076 0.836 von Mises stress 0.167 0.703 0.005 0.125

Relative warp 1 0.703 <0.0001 0.021 0.276

Geosaurinae Relative warp 2 0.692 0.032 0.022 0.254 von Mises stress 0.855 <0.0001 <0.0001 0.145

B. Taxon subsampling

Methodology : Two tests were devised to test how sensitive of our initial results are to the presence and/or absence of each taxon. In both tests the procedure for the maximum likelihood analyses was identical to the primary study, and was conducted for the family

(Metriorhynchidae) and both subclades (Metriorhynchinae, Geosaurinae). The first sensitivity test involved sequentially removing the data from each taxon prior to running the modelling analyses while keeping the tip in place . The second test follows the first but differs in that the taxon is removed from the tree as well as its data. In the first test the topology remains intact; therefore branch lengths are the same as same the primary analysis with only alteration being the distribution of the data within the family and subfamily groups. In the second test, the taxa are removed prior to the calculation of the branch lengths, thereby fundamentally altering the shape of the resultant phylogeny. In sum, the first test assumes the taxon has been sampled but the relevant data is unavailable, whereas the second test examines the effects of the trends assuming the taxon was never sampled in the first place.

Results : The RW1 form metric has no incongruence in any of the sensitivity analyses (for

Metriorhynchidae and both subclades) (Table S2 and S5). In other words, in both the full original analysis and all of the sensitivity analyses Brownian motion is found to be most likely for Metriorhynchidae and Geosaurinae, and stasis is most likely for Metriorhynchinae.

Therefore, these results are considered robust. The RW2 form metric exhibits limited incongruence between the full original analysis and the sensitivity analyses (Table S3 and

S6). There was no incongruence in either subclade analysis; in other words, stasis was always found for Metriorhynchinae and Brownian motion for Geosaurinae. These results, therefore, are considered robust. However, for Metriorhynchidae as a whole, the removal of a few taxa

( Suchodus brachyrhynchus , Dakosaurus maximus and Dakosaurus andiniensis ) changed the most likely mode of evolution from Brownian motion to stasis, while removal of

Gracilineustes leedsi changed the mode of evolution from Brownian motion to a directional trend. As these are only 4 of 19 taxa, however, and the deletion of the 15 other taxa does not change the pattern, the general result of Brownian motion is quite robust.

The function metric exhibits some incongruence from the initial result to those of the sensitivity analysis (Table S4 and S7) (see Figure S1 for the initial topology). For

Metriorhynchinae as a whole the incongruence is limited: removal of a few taxa

( Gracilineustes leedsi , Gracilineustes acutus , Cricosaurus araucanensis in both analyses; also Metriorhynchus superciliosus for the “tip removed” analysis) changed the most likely result from a directional trend to Brownian motion. Incongruence is more marked in the two subclades. For Metriorhynchinae, removal of Metriorhynchus superciliosus or

Metriorhynchus geoffroyii changed the pattern of evolution from a directional trend to stasis, while removal of any other taxon changed the metriorhynchine pattern from a directional trend to Brownian motion. For Geosaurinae removal of any taxon changes the pattern of evolution from Brownian motion to a directional trend. Therefore, the results for the two subclades may not seem robust. However, by deleting taxa from a small dataset, these sensitivity analyses are hampered by a small sample size (n=8 for metriorhynchines; n=5 for geosaurines). What is most important is that the sensitivity analyses for Metriorhynchinae as a whole, which is a large dataset (n=13), show that the results recovered by the full analysis are quite robust, as only deletion of a few select taxa change the patterns. The fact that a consistent pattern is repeatedly recovered for Metriorhynchidae (save with the deletion of a few taxa) suggests that, although the addition or subtraction of taxa may alter the results of the subclade analyses (an unfortunate reality for small datasets), the overarching pattern of a directional trend in metriorhynchid functional evolution is robust

In summary, sensitivity analyses show: 1) the general pattern of phenotypic evolution for Metriorhynchidae, Metriorhynchinae and Geosaurinae are robust for both form metrics; 2)

craniofacial form in Metriorhynchinae and Geosaurinae were undergoing different modes of evolution (metriorhynchine form metrics are best explained as evolving under stasis; geosaurine form metrics are best explained as evolving under Brownian motion); 3) functional evolution in metriorhynchids as a whole is robustly explained as directional; 4) craniofacial function in Metriorhynchinae and Geosaurinae was likely undergoing different modes of evolution, but small sample sizes may hamper interpretation and confound the maximum likelihood methods.

FIGURE S1. A) von Mises stress contour plots of metriorhynchid crania in dorsal-aspect.

These are placed within phylogenetic context and have the major clades labelled. Figure modified from Young et al . (2010). B) Labelled metriorhynchid FE-model highlighting the location of: applied forces, boundary conditions and were the nodes for function metric were selected. The function metric was derived from the finite element analysis reported in Young et al. (2010), in which the methodology is detailed. In sum, (x,y) co-ordinates of metriorhynchid crania in dorsal aspect were captured using the Freeware ImageJ

(http://rsb.info.nih.gov/ij). These were imported into the Cosmos finite element analysis package (v2.95, 256K; http://www.cosmosm.com). Spline curves were used to connect the co-ordinate positions of: both supratemporal fenetrae and the outer margin of the skull. The models were then meshed, creating the planar FE-models composed of approximately 13,000 three-noded triangular elements. All the models were then scaled to the same length. Only cranial bone was modelled, and was treated as homogeneous and isotropic. A Young’s modulus of 5.6 GPa, and Poisson’s ratio of 0.29 was selected (see Young et al., 2010 for further information). The FE-models were constrained by preventing translation at the left and right quadrates (jaw joint), with the nodes along the posterior outer margin of quadrates

being constrained. A 1000 Newton bilateral bite was applied to the nodes corresponding to the anterior maxillary teeth in the z-direction.

Table S2: AICc weights for the four maximum likelihood models of Metriorhynchidae and its two subfamilies, with the most likely model highlighted in bold. These sensitivity analyses results were conducted on the first form metric (RW1) under the first method.

Species removed Metriorhynchidae Metriorhynchinae Geosaurinae

URM GRW OU Stasis URM GRW OU Stasis URM GRW OU Stasis

Original analysis (no removal) 0.672 0.171 0.157 <0.001 0.198 0.105 0.063 0.634 0.800 <0.001 0.024 0.176

Teleidosaurus calvadosii 0.653 0.201 0.146 <0.001 - - - - -

Metriorhynchus superciliosus 0.673 0.176 0.151 <0.001 0.132 0.045 0.049 0.775 -

-

-

-

-

-

-

Metriorhynchus geoffroyii

Metriorhynchus sp.

Metriorhynchus hastifer

Gracilineustes leedsi

0.686

0.679

0.160

0.169

0.154 <0.001 0.305

0.152 <0.001

0.075 0.040

0.180 <0.001 0.048

0.580

0.773

-

-

0.686 0.160 0.154 <0.001

0.332 0.082 0.038 0.547 -

0.688 0.157 0.154 <0.001 0.223 0.035 0.047 0.696 -

-

-

-

-

-

-

-

-

-

-

-

-

Gracilineustes acutus

Rhacheosaurus gracilis

0.817 <0.001 0.183 <0.001 0.300 0.047 0.044 0.609 -

0.690 0.155 0.155 <0.001 0.221 0.038 0.049 0.692 -

Cricosaurus suevicus

Cricosaurus vignaudi

Cricosaurus araucanensis

0.676 0.172 0.152 <0.001 0.215 0.192 0.035 0.558 -

0.817 <0.001 0.183 <0.001 0.172

0.683 0.163 0.153 <0.001 0.222 0.081 0.040 0.656 -

0.817 <0.001 0.183 <0.001 -

0.066

-

0.044

-

0.719

-

-

0.669

-

-

-

0.005

-

-

-

-

-

-

0.005 0.321 Suchodus brachyrhynchus

Suchodus durobrivensis 0.680 0.168 0.153 <0.001 -

Purranisaurus casamiquelai 0.683 0.164 0.153 <0.001 -

-

-

-

-

-

-

0.717

0.734

<0.001 0.005 0.278

<0.001 0.005 0.261

Torvoneustes carpenteri

Geosaurus grandis

Dakosaurus manselii

Dakosaurus maximus

0.685

0.684 0.163 0.153 <0.001 -

0.671

0.162

0.179

0.154 <0.001

0.150 <0.001

-

-

0.683 0.163 0.153 <0.001 -

-

-

-

-

-

-

-

-

-

-

-

-

0.771

0.833

0.759

0.687

-

-

0.009

0.008

0.006

0.006

-

-

-

-

0.005 0.215

0.006 0.153

0.005 0.230

0.005 0.303

Dakosaurus andiniensis 0.685 0.161 0.154 <0.001 - - - - 0.793 <0.001 0.005 0.201

Table S3: AICc weights for the four maximum likelihood models of Metriorhynchidae and its two subfamilies, with the most likely model highlighted in bold. These sensitivity analyses results were conducted on the second form metric (RW2) under the first method.



Original analysis (no removal) 0.450 0.181 0.189 0.179 0.055 0.007 0.081 0.858 0.780 0.041 0.024 0.156

Teleidosaurus calvadosii 0.591 <0.001 0.177 0.231 - - - - -

Metriorhynchus superciliosus 0.608 0.151 0.170 0.070 0.126 0.009 0.050 0.816 -

-

-

-

-

-

-


Metriorhynchus sp.



0.512

0.426

0.162

0.159

0.188 0.138 0.094 0.006 0.055

0.196 0.219 0.069 0.005 0.055

0.844

0.871

-

-

0.442 0.161 0.192 0.205 0.075 0.006 0.055 0.865 -

0.294 0.499 0.111 0.096 0.089 0.111 0.048 0.752 -

-

-

-

-

-

-

-

-

-

-

-

-



0.448 0.189 0.178 0.186 0.084 0.007 0.054 0.855 -

0.442 0.254 0.152 0.150 0.051 0.006 0.054 0.888 -




0.434 0.166 0.191 0.209 0.073 0.006 0.055 0.866 -

0.454 0.196 0.155 0.195 0.087 0.008 0.052

0.466 0.172 0.166 0.196 0.053 0.004 0.054 0.889 -

0.329 0.116 0.159 0.397 - - -

0.854

-

-

0.692

-

-

-

-

-

-

-

-

-

0.006 0.005 0.297 Suchodus brachyrhynchus

Suchodus durobrivensis 0.383 0.143 0.143 0.331 -

Purranisaurus casamiquelai 0.405 0.147 0.199 0.248 -

-

-

-

-

-

-

0.702

0.719

0.008 0.005 0.285

0.009 0.005 0.267


Geosaurus grandis



0.494

0.490 0.245 0.147 0.117 -

0.211

0.197

0.075

0.161 0.148

0.282 0.432

-

-

0.306 0.132 0.187 0.376 -

-

-

-

-

-

-

-

-

-

-

-

-

0.828

0.848

0.730

0.700

-

-

-

-

-

-

0.010 0.006 0.157

0.016 0.006 0.130

0.008 0.005 0.256

0.010 0.005 0.295

Dakosaurus andiniensis 0.453 0.221 0.139 0.188 - - - - 0.788 0.016 0.005 0.191

Table S4: AICc weights for the four maximum likelihood models of Metriorhynchidae and its two subfamilies, with the most likely model highlighted in bold. These sensitivity analyses results were conducted on the function metric (mean von Mises stress) under the first method.



Original analysis (no removal) 0.305 0.644 0.049 0.002 0.182 0.679 0.005 0.134 0.824 <0.001 <0.001 0.176


Metriorhynchus geoffroyii 0.332 0.619 0.047 0.004 0.299 0.398 0.002 0.302 -

-

-

-

-

-

-

Metriorhynchus sp.




0.374

0.355

0.568

0.590

0.053

0.050

0.005

0.005

0.408 0.192 0.003 0.398

0.366 0.260 0.003 0.372

-

-

0.614 0.298 0.086 0.003 0.737 0.071 0.005 0.188 -

0.519 0.407 0.073 <0.001 0.524 0.393 0.004 0.079 -

-

-

-

-

-

-

-

-

-

-

-

-



Suchodus durobrivensis




Dakosaurus andiniensis

0.459 0.471 0.064 0.006 0.506 0.172 0.003 0.319 -

0.529 0.390 0.074 0.007 0.475 0.102 0.003 0.420 -

0.385

0.409

0.371 0.564 0.052 0.013 -

0.264

0.556

0.531

0.689

0.054

0.057

0.037

0.006

0.003

0.010

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

<0.001

<0.001

<0.001

<0.001

<0.001

-

-

0.502

0.530

0.945

0.509

0.501

-

-

0.499

0.470

0.055

0.492

0.499

-

-

<0.001

<0.001

<0.001

<0.001

<0.001

Table S5: AICc weights for the four maximum likelihood models of Metriorhynchidae and its two subfamilies, with the most likely model highlighted in bold. These sensitivity analyses results were conducted on the first form metric (RW1) under the second method.



Original analysis (no removal) 0.672 0.171 0.157 <0.001 0.198 0.105 0.063 0.634 0.800 <0.001 0.024 0.176

Teleidosaurus calvadosii 0.652 0.201 0.146 <0.001 - - - - -

Metriorhynchus superciliosus 0.677 0.171 0.152 <0.001 0.134 0.050 0.047 0.770 -

-

-

-

-

-

-


Metriorhynchus sp.



0.687

0.681

0.159

0.167

0.154 <0.001 0.288

0.153 <0.001

0.170

0.090

0.129

0.036

0.040

0.587

0.661

-

-

0.686 0.160 0.154 <0.001

0.278 0.086 0.037 0.599 -

0.689 0.156 0.155 <0.001 0.199 0.040 0.044 0.722 -

-

-

-

-

-

-

-

-

-

-

-

-



0.690 0.155 0.155 <0.001 0.263 0.050 0.040 0.647 -

0.690 0.155 0.155 <0.001 0.184 0.037 0.045 0.734 -




0.676 0.172 0.152 <0.001 0.160 0.239 0.034 0.567 -

0.817 <0.001 0.183 <0.001 0.171 <0.001 0.476

0.683 0.163 0.153 <0.001 0.213 0.081 0.041 0.665 -

0.817 <0.001 0.183 <0.001 - - -

0.781

-

-

0.558

-

-

-

0.004

-

-

-

-

-

-


Suchodus durobrivensis 0.680 0.168 0.153 <0.001 -

Purranisaurus casamiquelai 0.683 0.164 0.153 <0.001 -

-

-

-

-

-

-

0.606

0.626

<0.001 0.004 0.389

<0.001 0.004 0.369


Geosaurus grandis



0.688

0.684 0.163 0.153 <0.001 -

0.669

0.158

0.181

0.154 <0.001

0.150 <0.001

-

-

0.683 0.163 0.153 <0.001 -

-

-

-

-

-

-

-

-

-

-

-

-

0.684

0.799

0.708

0.655

-

-

0.009

-

-

-

-

0.005 0.302

<0.001 0.005 0.196

<0.001 0.006 0.286

0.007 0.004 0.334

Dakosaurus andiniensis 0.685 0.161 0.154 <0.001 - - - - 0.681 <0.001 0.004 0.315

Table S6: AICc weights for the four maximum likelihood models of Metriorhynchidae and its two subfamilies, with the most likely model highlighted in bold. These sensitivity analyses results were conducted on the second form metric (RW2) under the second method.



Original analysis (no removal) 0.450 0.181 0.189 0.179 0.055 0.007 0.081 0.858 0.780 0.041 0.024 0.156

Teleidosaurus calvadosii 0.465 0.211 0.140 0.183 - - - - -

Metriorhynchus superciliosus 0.580 0.168 0.167 0.084 0.390 <0.001 0.035 0.575 -

-

-

-

-

-

-


Metriorhynchus sp.



0.491

0.463

0.159 0.191 0.158 0.116

0.l62 0.188 0.186 0.117

0.008

0.009

0.050

0.050

0.826

0.825

-

-

0.466 0.164 0.187 0.184 0.118 0.009 0.050 0.823 -

0.307 0.490 0.110 0.093 0.122 0.306 0.033 0.540 -

-

-

-

-

-

-

-

-

-

-

-

-



0.451 0.182 0.180 0.187 0.122 0.010 0.050 0.819 -

0.442 0.254 0.153 0.151 0.079 0.011 0.052 0.859 -




0.441 0.170 0.186 0.203 0.099 0.008 0.051 0.842 -

0.454 0.196 0.155 0.195 0.104

0.466 0.172 0.166 0.196

0.065 0.005 0.053 0.877 -

0.329 0.116 0.159 0.397

-

0.009

-

0.051

-

0.836

-

-

0.533

-

-

-

0.004

-

-

-

-

-

-


Suchodus durobrivensis 0.383 0.143 0.143 0.331 -


-

-

-

-

-

-

0.581

0.612

<0.001 0.004 0.415

0.006 0.005 0.377


Geosaurus grandis



0.496 0.224 0.142 0.138

0.490 0.245 0.147 0.117 -

0.202 0.072 0.275 0.452

-

-

0.306 0.132 0.187 0.376 -

-

-

-

-

-

-

-

-

-

-

-

-

0.747

0.814

0.696

0.652

-

-

0.010

0.013

0.006

0.014

-

-

-

-

0.005 0.238

0.005 0.167

0.006 0.293

0.004 0.330

Dakosaurus andiniensis 0.453 0.221 0.139 0.188 - - - - 0.678 0.013 0.005 0.304

Table S7: AICc weights for the four maximum likelihood models of Metriorhynchidae and its two subfamilies, with the most likely model highlighted in bold. These sensitivity analyses results were conducted on the function metric (mean von Mises stress) under the second method.



Original analysis (no removal) 0.305 0.644 0.049 0.002 0.182 0.679 0.005 0.134 0.824 <0.001 <0.001 0.176


Metriorhynchus geoffroyii 0.325 0.625 0.046 0.004 0.468 <0.001 0.004 0.529 -

-

-

-

-

-

-

Metriorhynchus sp.




0.370

0.360

0.573

0.585

0.052

0.050

0.005

0.004

0.405

0.371

0.237

0.271

0.003 0.354

0.003 0.355

-

-

0.638 0.271 0.089 0.002 0.780 0.060 0.005 0.155 -

0.507 0.422 0.070 <0.001 0.474 0.437 0.003 0.086 -

-

-

-

-

-

-

-

-

-

-

-

-



Suchodus durobrivensis





0.459 0.471 0.064 0.006 0.506 0.172 0.003 0.319 -

0.529 0.390 0.074 0.007 0.475 0.102 0.003 0.42 -

0.385

0.412

0.371 0.564 0.052 0.013 -

0.264

0.555

0.679

0.689

0.054

0.005

0.037

0.006

0.134

0.010

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

<0.001

<0.001

<0.001

<0.001

<0.001

-

-

0.502

0.530

0.948

0.509

0.510

-

-

0.498

0.470

0.050

0.491

0.490

-

-

<0.001

<0.001

<0.001

<0.001

<0.001

2) Systematic Palaeontology: Clade Definitions and Diagnoses

Formal diagnoses of all Metriorhynchidae family-group taxa are presented, in accordance with the Code of the International Commission on Zoological Nomenclature.

Superfamily Metriorhynchoidea Fitzinger, 1843

Teleidosaurus Eudes-Deslongchamps, 1869

Eoneustes Young et al ., 2010

Family Metriorhynchidae Fitzinger, 1843

Subfamily Metriorhynchinae Fitzinger, 1843

Metriorhynchus von Meyer, 1830

Gracilineustes Young et al ., 2010

Tribe Rhacheosaurini novum

Rhacheosaurus von Meyer, 1831

Cricosaurus Wagner, 1858

Subfamily Geosaurinae Lydekker, 1889

Suchodus Lydekker, 1890

Purranisaurus Rusconi, 1948

Neptunidraco Cau & Fanti, 2011

Tribe Geosaurini Lydekker, 1889

Torvoneustes Andrade et al ., 2010

Geosaurus Cuvier, 1824

Dakosaurus von Quenstedt, 1856

Superfamily Metriorhynchoidea Fitzinger, 1843

Type genus : Metriorhynchus von Meyer, 1830

Diagnosis : Thalattosuchian crocodylomorphs with three teeth per premaxillae; extremely enlarged foramen for the internal carotid artery; prefrontals anterior to the orbits were short and broad, orientated posteriormedially-anterolaterally; antorbital fenestrae absent; mandibular symphysis depth moderate (symphysis depth 4.5-6.0% of the mandible length).

Phylogenetic definition : the most inclusive clade consisting of Metriorhynchus geoffroyii von Meyer, 1832, but not Teleosaurus cadomensis (Lamouroux, 1820) (from Young &

Andrade, 2009).

Family Metriorhynchidae Fitzinger, 1843


Diagnosis : Thalattosuchian crocodylomorphs lacking conspicuous ornamentation on the external surface of the rostrum; orbit orientated fully laterally, although orbit shape is only clear in lateral view; prefrontals teardrop-shaped in dorsal view, with a convex outer margin; distinct frontoparietal crest, with the frontal width more than 75% wider than that of the parietal.

Equivocal synapomorphies 1 : the following characteristics are present in all metriorhynchids, absent in teleosauroid thalattosuchians, but are unknown in all basal metriorhynchoids: axis parapophysis is partially or wholly borne on the odontoid, five cervical vertebrae, caudal vertebrae have a ventral deflection creating a hypocercal tail; dorsal vertebrae parapophyses orientated anteriorly, mid to late dorsal vertebrae lack the shallow fossa on the anterior margin of the diapopohysis; sacral ribs strongly curved ventrally, articulation for ilium on the sacral rib is small; osteoderms absent; humerus shaft reduced, contributing less than 40% of total humeral length; humerus lacks the

proximomedially articular surface; humerus and scapulae subequal in length; coracoid fanshaped, with both proximal and distal ends convex; metacarpal I broadly expanded; digit IV elongated, making it the longest manus digit; ilium lacks posterior process, ilium dorsal border proportionally short; ischium anterior process reduced and lacking articulation facets; tibia shortened, measuring less than 45% of the femur length; calcaneum tuber poorly developed or vestigial; metatarsal I has an enlarged proximal end, metatarsals II through IV become progressively shorter; chevrons are ‘w’-shaped; parasphenoid visible in palatal view, forming a ridge along the pterygoids meeting the basisphenoid posteriorly.

Equivocal synapomorphies 2 : the following characteristics are present in all metriorhynchids, but are unknown in basal metriorhynchoids more derived than

Teleidosaurus calvadosii : external nares elongate and elliptical, external nares posterodorsally retracted; preorbital fossae present (not homologous to the archosaurian antorbital fossae/fenestrae, see Fernández & Herrera, 2009); infratemporal fenestra subequal in length with orbit; external mandibular fenestra absent; retroarticular process projects medially past the glenoid fossa, retroarticular process is foreshortened; surangular has a distinct coronoid process.

Equivocal synapomorphies 3 : the following characteristics are present in all metriorhynchids, but are unknown in basal metriorhynchoids more derived than

Teleidosaurus and Eoneustes : sclerotic ring within the orbit; preorbital fossae enclosed by the lacrimals, nasals and maxillae; prefrontal–lacrimal fossae present.

Phylogenetic definition : the least inclusive clade consisting of Metriorhynchus geoffroyii von Meyer, 1832 and Geosaurus giganteus (von Sömmerring, 1816) (from Young &

Andrade, 2009).

Subfamily Metriorhynchinae Fitzinger, 1843


Diagnosis : Thalattosuchian crocodylomorphs with atlas hypocentrum subequal in length to odontoid process; cervical vertebrae centra length shortened; anterior and mid-snout maxillary tooth crowns procumbent (i.e. not orientated perpendicular to the long-axis of the skull but have a distinct rostral orientation); lacrimal contributes less than 40% to the rostral margin of the orbit; maxillopalatine suture in palatal view forms an ‘M’-shape orientated posteriorly; surangular extends rostrally beyond the orbit along the dorsal margin of the mandible (can be obscured by dentary overlap in lateral view); tibia length further shortened, measuring less than 40% of the femur length.

Phylogenetic definition : the most inclusive clade consisting of Metriorhynchus geoffroyii von Meyer, 1832, but not Geosaurus giganteus (von Sömmerring, 1816) (from Young &

Andrade, 2009).

Tribe Rhacheosaurini novum

Type genus : Rhacheosaurus von Meyer, 1831

Diagnosis : Thalattosuchian crocodylomorphs with presacral vertebrae count increased by one

(to 25), number of caudal vertebrae increased by at least eight (>45); teeth lack carinae; reduction in premaxilla length posterior to the external nares (contributing 28% or less of total premaxillary length); prefrontals teardrop-shaped with a smooth convex outer margin that does not exceed the jugal bar in dorsal view; frontopostorbital suture lower than (ventral to) the interremporal bar; infratemporal fenestra length shorter than that of the orbit; supratemporal fossae (in dorsal view) extend rostrally at least as far of the postorbital; supratemporal fenestrae subequal in length with the orbit; in dorsal view, between the parietal-supraoccipital sutures the parietal is straight with an enclave for the supraoccipital; both angular and surangular bones extend rostrally beyond the orbit; coronoid participates on

the lateral (external) face of the mandible; humerus deltopectoral crest absent or vestigial; humerus shaft greatly reduced, contributing less than 25% of total humeral length; radius and ulna are subequal in size to the radiale and ulnare, respectively; tibia length greatly shortened, measuring less than 30% of the femur length.

Phylogenetic definition : the most inclusive clade including Rhacheosaurus gracilis von

Meyer, 1831 but not Metriorhynchus geoffroyii von Meyer, 1832, and Gracilineustes leedsi

(Andrews, 1913).

Subfamily Geosaurinae Lydekker, 1889

Type genus : Geosaurus Cuvier, 1824

Diagnosis : Thalattosuchian crocodylomorphs with a rostrum transversely broader than dorsoventrally high; 17 or fewer teeth per maxillae; 18 or fewer teeth per dentary; base of postorbital process of the jugal is directed dorsally; maxillopalatine suture in palatal view forms a broad ‘U’-shape orientated anteriorly; internal choana forms a ‘W’-shape in palatal view; mandibular symphysis proportionally short (contributing less than 40% of total mandibular length); mandibular symphysis increasingly deep (symphysis depth more than 7% of the mandible length); the coronoid does not project as far rostrally as the dentary toothrow; glenoid fossae are orientated dorsally.

Phylogenetic definition : the most inclusive clade consisting of Geosaurus giganteus (von

Sömmerring, 1816), but not

Metriorhynchus geoffroyii von Meyer, 1832 (from Young &

Andrade, 2009)

Tribe Geosaurini Lydekker, 1889

Type genus : Geosaurus Cuvier, 1824

Diagnosis : Thalattosuchian crocodylomorphs with increasing apicobasal length of toothcrowns (exceeding 12 centimetres); contiguous serrations along the mesial and distal carinae of the teeth; reduction in size of the basal tubera; prefrontals teardrop-shaped, with the inflexion point directed caudally at an angle less than 70 degrees from the rostrocaudal axis of the skull; very narrow (close to 45 degrees) angle between the medial and the caudolateral processes of the frontal; supratemporal fossae (in dorsal view) extend caudally beyond the parietal; humerus shaft greatly reduced, contributing less than 25% of total humeral length.

Phylogenetic definition : the least inclusive clade consisting of Geosaurus giganteus (von

Sömmerring, 1816),

Dakosaurus maximus (Plieninger, 1846) and Torvoneustes carpenteri

(Wilkinson et al ., 2008) (modified from Cau & Fanti, 2011).

3) Supplementary References

Andrews CW. 1913.

A descriptive catalogue of the marine reptiles of the Oxford Clay , Part

Two. London: British Museum (Natural History).

Cau A, Fanti F. 2011. The oldest known metriorhynchid crocodylian from the Middle

Jurassic of North-eastern Italy: Neptunidraco ammoniticus gen. et sp. nov. Gondwana

Research 19 (2): 550-565.

Cuvier G. 1824.

Sur les ossements fossiles de crocodiles, 5. In: Dufour, D’Occagne, eds.

Recherches sur les ossements fossiles

, 2nd édn. Paris: Dufour & d’Occagne, 143–160.

Eudes-Deslongchamps E. 1869.

Mémoire sur les téléosauriens de la Normandie.

Bulletin de

la Société Linnéenne de Normandie, Série 2 3: 124–221.

Fernández MS, Herrera Y. 2009. Paranasal sinus system of

Geosaurus araucanensis and the homology of the antorbital fenestra of metriorhynchids (Thalattosuchia:

Crocodylomorpha). Journal of Vertebrate Paleontology 29 : 702-714.

Fitzinger LJFJ. 1843.

Systema reptilium

. Wien: Braumüller et Seidel.

Lamouroux JVF. 1820.

Sur le crocodile fossile trouvé dans les carrière du bourg. Annales

Générales des Sciences Physiques 3

: 160–163.

Lydekker R. 1889.

On the remains and affinities of five genera of Mesozoic reptiles.

Quarterly Journal of the Geological Society 45 : 41-59.

Lydekker, R. 1890.

On a crocodilian jaw from the Oxford Clay of Peterborough. Quarterly

Journal of the Geological Society, London 46 : 284-288.

Meyer CEH von. 1830.

Achte Versammlung der Naturforscher und Aerzte zu Heidelberg im

September 1829. Isis von Oken , 1830: 517-519.


Neue fossile Reptilien aus der Ordung der Saurier. Nova Acta

Academiae Leopoldino-Carolinae Curios 15 : 173-184.


Palaeologica zur Geschichte der Erde und ihrer Geshopfe . Frankfurt:

Meyer 560pp.

Plieninger T. 1846.

Prof. Dr. Th. Plieninger hielt nachstehenden vortrag über ein neues

Sauriergenus und die Einreihung der Saurier mit flachen, schneidenden Zähnen in eine Familie. Pp. 148–154 in: Zweite Generalversammlung am 1. Mai 1846 zu

Tübingen. Württembergische naturwissenschaftliche Jahreshefte 2 : 129–183.

Quenstedt FA von. 1856.

Sonst und Jetzt: Populäre Vortäge über Geologie

. Tübingen:

Laupp, 131.

Rusconi C. 1948.

Nuevo plesiosaurio pez y Langostas del mar Jurassico de Mendoza. Revista

del Museo de Historia Natural de Mendoza 2 : 3-12.

Sömmerring ST von. 1816.

Ueber die Lacerta gigantea der vorwelt. Denkschriften der

Königlichen Akademie der Wisseschaften zu Münch 6

: Classe der Mathematik und

Naturwissenschaften 37-59.

Wagner A. 1858. Zur Kenntniss der Sauier aus den lithographischen Schiefen. Abhandlungen der Mathemat.-Physikalischen Classe der Königlich Bayerischen Akademie der

Wissenschaften 8 : 415-528.

Wilkinson LE, Young MT, Benton MJ. 2008.

A new metriorhynchid crocodile

(Mesoeucrocodylia: Thalattosuchia) from the Kimmeridgian (Upper Jurassic) of

Wiltshire, UK. Palaeontology 51 : 1307-1333.

Young MT, Andrade MB. 2009.

What is Geosaurus ? Redescription of G. giganteus

(Thalattosuchia, Metriorhynchidae) from the Upper Jurassic of Bayern, Germany.

Zoological Journal of the Linnean Society 157 : 551–585.

4 ) Form and Function Raw Data

The relative warps scores and mean von Mises stress values were taken from the analyses presented in Young et al . (2010).

Species

Teleidosaurus calvadosii

RW1 RW2

0.030 -0.010

Metriorhynchus superciliosus 0.038 0.016 von Mises stress

-

3.57


Metriorhynchus sp.





0.063 -0.035

0.019 -0.021

0.061 -0.023

0.039 -0.025

0.092 -0.020

0.098 0.003

3.71

4.12

3.94

3.80

6.13

5.56




Suchodus brachyrhynchus

0.019 -0.021

0.061 -0.023

0.079 -0.040

-0.062 0.034

Suchodus durobrivensis -0.071 0.011

Purranisaurus casamiquelai -0.038 0.003

Torvoneustes carpenteri -0.031 -0.011

Geosaurus grandis




-0.059 0.002

-0.164 -0.081

-0.131 -0.062

-0.103 -0.038

-

-

6.19

-

2.50

2.23

3.20

-

-

1.50

1.37

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