Elasmosauridae, Vakil & Webb & Cook, 2021
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publication ID |
https://doi.org/ 10.26879/1095 |
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persistent identifier |
https://treatment.plazi.org/id/039687B5-D65A-FFA2-1F14-2A944F50FA8B |
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treatment provided by |
Felipe |
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scientific name |
Elasmosauridae |
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Elasmosauridae gen. et sp. indet. (RM FR436)
Figure 10 View FIGURE 10
Material. Partial postcranial material with 12 isolated vertebrae.
Locality. Near Richmond, Queensland (exact locality unknown).
Stratigraphic horizon. Toolebuc Formation (late Albian)
Description. Twelve isolated, anterior cervical vertebrae (CW = 91.2 – 61.85 mm; CH = 62.65 – 42.1 mm; CL could not be measured owing to distortion) are free of matrix ( Figure 10A View FIGURE 10 ). All centra are complete, but most appear to be dorso-ventrally flattened and sheared, thereby distorting CL measurements. Vertebrae have faintly visible foramina subcentralia and lack fused elements. All vertebrae bear faint lateral ridges and well-developed dumbbell-shaped articular facets obscured by distortion ( Figure 10C View FIGURE 10 ) (Otero et al., 2014; Sachs and Kear, 2017).
Remarks. The original sequence of vertebrae is lost and the current sequence is based loosely on vertebra size. The lateral ridges and dumbbell-shaped articular facets are consistent with an elasmosaurid identification (Otero et al., 2014). Based on the osteological immaturity of the vertebrae, with open neurocentral sutures, and their size, the specimen appears to be a subadult. It is important to note that all vertebrae have been sheared differentially; some are skewed left dorsally whereas others are skewed right dorsally ( Figure 10 View FIGURE 10 ; Appendix Figure 1 View FIGURE 1 ). Since shearing was almost certainly caused during compaction, we can infer that the vertebrae were lying on their sides postmortem, but not all were oriented in the same direction. As the original sequence of vertebrae is not preserved, three hypotheses may explain their orientations. If the order reconstructed on the basis of size is correct ( Figure 10A View FIGURE 10 ; Appendix Figure 1A View FIGURE 1 ), individual vertebrae toppled to either side (Appendix Figure 1B View FIGURE 1 ), followed by shearing. Alternately, the vertebrae may represent two or more sections of neck that were deposited on different sides (Appendix Figure 1C View FIGURE 1 ) and were sheared together
PALAEO- ELECTRONICA.ORG in sections. This would require that the order based on size is incorrect. Finally, the vertebrae may have been disarticulated completely upon deposition, ending up resting in different random orientations prior to compaction (Appendix Figure 1D View FIGURE 1 ). This would explain the irregular ordering of the shearing, but would require that none of the vertebrae were deposited on dorsal or ventral surfaces. At this time, the lack of detailed excavation notes makes it impossible to exclude one of the options. Owing to the incomplete data, this specimen was not included in further analyses.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.