Variability of vertebral laminae in eight specimens of Plateosaurus (Saurischia, Sauropodomorpha)

Data associated with: • Regalado Fernández, Omar R. (2024) Variability of vertebral laminae in eight specimens of Plateosaurus (Saurischia, Sauropodomorpha). Revue de Paléobiologie, Genève 43(1):85-100. 10.5281/zenodo.10732345 METHODS A region in the type SMNS 13200 was defined as a set of vertebrae with the same laminae. The different specimens were then mapped onto this for comparison. In addition, this regionalisation was codified in a string of 0/1 for the absence (0) or presence (1) of laminae in that region. In specimen SMNS 13200, the cervical vertebrae sets are Ce3-Ce4, Ce5-Ce6, Ce7-Ce8, and Ce9-Ce10. A string reflecting the appearance of vertebral laminae was produced for each lamina. For instance, the sprl is present from Ce7 onwards, thus coded as 0011, and the same lamina in specimen MB.R.2090 – present from Ce3 onwards – would be coded as 1111. In the case of the dorsal vertebrae, the sets of vertebrae are D1, D2-3, D4-7, D8-D11, D12-D13, and D14-D15. The same lamina, cprl, would thus be coded 110001 in specimen SMNS 13200 but 111111 in MB.R.2090. The type materials for Ruehleia and Adeopapposaurus were included for comparison. The laminae of Ruehleia were described using specimen MB.R.4718, whereas the laminae of Adeopapposaurus were taken from the literature (Martínez, 2009; Barrett et al., 2019). Approximately seven Ruehleia specimens were discovered in the locality Großen Gleichberg, Römhild, Germany, and are considered to be from the Steinmergelbank, Trossingen Formation (von Huene, 1934); the phylogenetic position of Ruehleia has been suggested to be either more closely related to Plateosaurus than to other early-diverging sauropodomorphs (McPhee et al., 2015) or as part of a Plateosauridae clade (Peyre de Fabrègues & Allain, 2020; Regalado Fernández & Werneburg, 2022). Adeopapposaurus, on the other hand, has been found nested within the clade Massospondylidae, as being more closely related to Massospondylus than to Plateosaurus (McPhee et al., 2015; Chapelle et al., 2019; Peyre de Fabrègues & Allain, 2020). Specimen MB.R.4404 was described in detail by Jaekel (1914) as a plateosaurid with 23 presacral vertebrae. In Jaekel (1914: fig. 15), the neck is indicated to have 10 cervical vertebrae; however, the count in the drawing considers the odontoid process and the axis as two cervicals, suggesting that specimen MB.R.4404 has 9 cervicals instead of 10. Based on Jaekel (1914: fig. 12), the cervical with the numeral 11 corresponds to the 10th cervical vertebra based on the illustrated morphology, i.e. the parapophysis is set anteriorly to the diapophysis, the centrum has the same morphology as the preceding cervical vertebra but different than the following one, and the rib is shorter and would articulate closer to parallel to neck’s ventral plane. The vertebra with the numeral 12 would correspond to the 1st dorsal vertebra, tallying 13 dorsal vertebrae, instead of the 15 counted in the other specimens, and similar to the count in Adeopapposaurus (Martínez, 2009). Unfortunately, it is not possible to corroborate this as only a few elements of the postcranial skeleton of MB.R.4404 are preserved, with most of them lost (Galton, 2001b). To code the specimens, Adeopapposaurus and MB.R.4404 were scored as “0” for all the laminae in the sixth dorsal region (D14-D15). Three matrices were then produced: one matrix with the strings that reflect the vertebral laminae in the cervical region, another one with the strings that reflect the dorsal region, and a third matrix that contains the strings of the postaxial presacral vertebrae together. The vertebral column is only preserved completely in SMNS 13200 and GPIT-PV-30784. In Tables 1-2, the question marks represent the absence of vertebrae from that region.