TABLE 1. Plesiosauromorph specimens examined for this research.
| Specimen | Locality | Formation | Age | Current Location | Material |
| QM F12719 | Stewart Creek, Dunraven Station, Central Queensland | Toolebuc | late Albian | Queensland Museum | 27 isolated vertebrae free of matrix, of which some are crushed and others are cojoined; disarticulated cranial elements, isolated teeth. |
| QM F11050 (Holotype) | Yambore Creek, near Maxwetton, Central Northern Queensland | Toolebuc | late Albian-early Aptian | Queensland Museum | A badly crushed skull, 5 vertebrae free of matrix of which 2 are cojoined. |
| QM F12934 | Kentle Downs, south of Hughenden | Allaru | late Albian | Queensland Museum | 36 isolated vertebrae free of matrix |
| RM FR269 | Richmond | Toolebuc | late Albian | Kronosaurus Korner | 55 vertebrae free of matrix of which some are cojoined, while others are isolated; rib fragments, parts of the right and left front paddles, propodial elements |
| QM F2085 | Flinders River, about 4.8 km. from Richmond. | Toolebuc | late Albian | Queensland Museum | 22 vertebrae free of matrix of which some are cojoined while others are isolated. |
| QM L39 | Near Bore Drain on ‘Lydia Downs’ Station, north of Nelia at Julia Creek | Toolebuc | late Albian | Queensland Museum | 6 isolated vertebrae free of matrix |
| RM FR436 | Richmond | Toolebuc | late Albian | Kronosaurus Korner | 12 isolated vertebrae free of matrix. |
| QM F171282 | Flinders River, about 4.8 km. from Richmond | Toolebuc | late Albian | Queensland Museum | Isolated vertebra free of matrix |
| QM PL | Unknown (Central Queensland?) | Queensland Museum | 2 isolated vertebrae free of matrix |
TABLE 2. PCA scores, percent variance and eigenvalues for shape variables for anterior cervicals of newly described Australian xenopsarian specimens (including previously described QM F3567 from Sachs (2004), but excluding polycotylid QM F12719) and anterior cervicals of non-Australian plesiosauromorph specimens. Data for QM F3567 and RM FR271 from Sachs (2004); Opallionectes andamookaensis from Kear (2005a); Elamosaurus platyurus, Thalassomedon haningtoni, Callawayasaurus colombiensis and Cm Zfr 115 from O’Keefe and Hiller (2006); Aristonectes quiriquinensis from Otero et al. (2014); Albertonectes vanderveldei from Kubo et al. (2012); Vegasaurus molyi from O’Gorman el. (2015); Tuarangisaurus keyesi from Hiller et al. (2017); AMNH FARB 1495, AMNH FARB 5835, Styxosaurus snowii, and AMNH FARB 2554 from Otero (2016); Aristonectes parvidens from O’Gorman (2016a); Kawanectes lafquenianus from O’Gorman (2016b); Lagenanectes richterae from Sachs et al. (2017) and Jucha squalea from Fischer et al. (2020).
| Loadings | PC 1 | PC 2 | PC 3 |
| HI | 0.5269 | -0.4248 | 0.73615 |
| BI | 0.83701 | 0.10892 | -0.53623 |
| BHI | 0.14761 | 0.89871 | 0.41295 |
| Eigenvalue | 640.871 | 275.432 | 1.78314 |
| % variance | 69.805 | 30.001 | 0.19422 |
TABLE 3. MANOVA results with Pillai’s Trace values for group pairs of xenopsarian specimens examined (CV: cervicals; alpha value = 0.05). Data for QM F3567 and RM FR271 from Sachs (2004); Opallionectes andamookaensis from Kear (2005a); Elamosaurus platyurus, Thalassomedon haningtoni, Callawayasaurus colombiensis and Cm Zfr 115 from O'Keefe and Hiller (2006); Aristonectes quiriquinensis from Otero et al. (2014); Albertonectes vanderveldei from Kubo et al. (2012); Vegasaurus molyi from O’Gorman el. (2015); Tuarangisaurus keyesi from Hiller et al. (2017); AMNH FARB 1495, AMNH FARB 5835, Styxosaurus snowii, and AMNH FARB 2554 from Otero (2016); Aristonectes parvidens from O’Gorman (2016a); Kawanectes lafquenianus from O’Gorman (2016b); Lagenanectes richterae from Sachs et al. (2017) and Jucha squalea from Fischer et al. (2020).
| Group 1 | Group 2 | Pillai's | df1 | df2 | F | p-value |
| Australian elasmosaurs | QM F3567 | 0.5438 | 3 | 30 | 11.92 | 2.61E-05 |
| Elasmosaurines | QM F3567 | 0.04133 | 3 | 92 | 1.322 | 0.272 |
| Elasmosaurines | Aristonectines | 0.8789 | 3 | 107 | 258.9 | 6.87E-49 |
| O. andamookaensis | Aristonectines | 0.1005 | 3 | 21 | 0.7819 | 0.5173 |
| O. andamookaensis | Australian elasmosaurs | 0.5664 | 3 | 28 | 12.19 | 2.77E-05 |
| Elasmosaurines | V. molyi | 0.6565 | 3 | 105 | 66.88 | 2.92E-24 |
| Elasmosaurines | T. keysi | 0.147 | 3 | 92 | 5.286 | 2.09E-03 |
| V. molyi | T. keysi | 0.7489 | 3 | 21 | 20.87 | 1.66E-06 |
| V. molyi | Aristonectines | 0.8344 | 3 | 36 | 60.48 | 3.92E-14 |
| T. keysi | Aristonectines | 0.8668 | 3 | 23 | 49.87 | 3.17E-10 |
| C. colombiensis | Australian elasmosaurs | 0.2584 | 3 | 30 | 3.485 | 0.02781 |
| T. haningtoni | Australian elasmosaurs | 0.4669 | 3 | 35 | 10.22 | 5.62E-05 |
| T. haningtoni | C. colombiensis | 0.1759 | 3 | 13 | 0.9252 | 4.56E-01 |
| C. colombiensis | Elasmosaurines | 0.4284 | 3 | 92 | 22.98 | 3.45E-11 |
| CM Zfr 115 | Australian elasmosaurs | 0.771 | 3 | 41 | 46.02 | 3.46E-13 |
| AMNH FARB 2254 | Australian elasmosaurs | 0.5694 | 3 | 33 | 14.55 | 3.31E-06 |
| Elasmosaurines | Australian elasmosaurs | 0.4602 | 3 | 114 | 32.4 | 3.21E-15 |
| Aristonectines | Australian elasmosaurs | 0.8132 | 3 | 45 | 65.3 | 1.99E-16 |
| V. molyi | Australian elasmosaurs | 0.4117 | 3 | 43 | 10.03 | 3.92E-05 |
| C. colombiensis | Aristonectines | 0.7155 | 3 | 23 | 19.28 | 1.79E-06 |
| L. richterae | Australian elasmosaurs | 0.5687 | 3 | 30 | 13.18 | 1.15E-05 |
| L. richterae | Elasmosaurines | 0.7249 | 3 | 92 | 80.83 | 1.08E-25 |
| L. richterae | Aristonectines | 0.7695 | 3 | 23 | 25.6 | 1.64E-07 |
| J. squalea | Australian elasmosaurs | 0.158 | 3 | 36 | 2.252 | 0.09894 |
| J. squalea | Elasmosaurines | 0.4009 | 3 | 98 | 21.86 | 6.39E-11 |
| J. squalea | Aristonectines | 0.9184 | 3 | 29 | 108.8 | 7.01E-16 |
| K. lafquenianus | CmZfr115 | 0.279 | 3 | 22 | 2.838 | 6.14E-02 |
| K. lafquenianus | Australian elasmosaurs | 0.8108 | 3 | 33 | 47.13 | 5.00E-12 |
| K. lafquenianus | Elasmosaurines | 0.6012 | 3 | 95 | 47.75 | 6.61E-19 |
| K. lafquenianus | Aristonectines | 0.9169 | 3 | 26 | 95.67 | 3.60E-14 |
TABLE 4. Non-Australian plesiosauromorph specimens examined for this study.
| Taxon | Specimen | Author |
| Styxosaurus sp. (“Hydralmosaurus serpentinus”) |
AMNH FARB 1495 | Cope, 1877 (see Otero, 2016) |
| Styxosaurus snowii | KUVP 1301 | Williston, 1890 |
| Elasmosaurus platyurus | ANSP 10081 | Cope, 1868 |
| Thalassomedon haningtoni | DMNH 1588 | Welles, 1943 |
| Vegasaurus molyi | MLP 93-I-5-1 | O’Gorman et al., 2015 |
| Albertonectes vanderveldei | TMP.2007.011.0001 | Kubo et al., 2012 |
| Aristonectes quiriquinensis | SGO.PV.957 | Otero et al., 2014 |
| Aristonectes parvidens | MLP 40-XI-14-6 | Cabrera, 1941 |
| Tuarangisaurus keyesi | NZGS CD426 | Wiffen and Moisley, 1986 |
| Callawayasaurus colombiensis | UCMP 38349 | Welles, 1963 |
| “Cimoliasaurus magnus” | AMNH FARB 2554 | Leidy, 1851 |
| Styxosaurus browni | AMNH 5835 | Welles, 1952 |
| Indeterminate elasmosaurid | CM Zfr 115 | |
| Kawanectes lafquenianus | MLP 71-II-13-1 | O’Gorman, 2016 |
| Lagenanectes richterae | BGR Ma 13328 | Sachs et al., 2017 |
| Jucha squalea | UPM 2756/1-53 | Fischer et al., 2020 |
