he workflow for establishing a hybrid framework to estimate body mass in plesiosaurs. (A) Acquire data from fossil specimens (illustrated here using the modified image of Sachicasaurus vitae, Paramo-Fonseca, Benavides-Cabra & Gutierrez, 2018, CC BY 4.0). (B) Create lateral-view silhouettes of skeletal elements. (C) Estimate the dimensions of missing fossil elements through regression formulae and/or comparisons with closely related taxa. (D) Reconstruct the main body axis, including the dimensions and shape of the skull and vertebral column. (E) Reconstruct the ribcage in both lateral view and transverse cross-sections jointly, then restore the soft-tissue outlines of the main body axis and the flippers. (F) Estimate the body mass using the cross-sectional method (Zhao, 2024). (G) Establish body mass equations from the mass estimates of multiple species. Elements in this figure are not to scale. https://doi.org/10.7717/peerj.21146/fig-1
Silhouettes of representative plesiosaur models from different clades, showing the reconstructed body outlines and transverse cross-sections. All models are scaled to the same length. (A) Thalassomedon haningtoni. (B) Aristonectes quiriquinensis. (C) Sachicasaurus vitae. (D) Liopleurodon ferox (E) Abyssosaurus nataliae. (F) Cryptoclidus eurymerus. (G) Martinectes bonneri. (H) Polycotylus latipinnis. (I) Meyerasaurus victor. (J) Macroplata tenuiceps. (K) Seeleyosaurus guilelmiimperatoris. (L) Microcleidus tournemirensis. (M) Nichollssaura borealis. (N) Brancasaurus brancai. (O) Plesiopterys wildi. https://doi.org/10.7717/peerj.21146/fig-4
Representative plesiosaur reconstructions created in this study. (A) Kronosaurus queenslandicus. (B) Albertonectes vanderveldei. (C) Aristonectes quiriquinensis. (D) Plesiopterys wildi. (E) Brancasaurus brancai. (F) Liopleurodon ferox. (G) Seeleyosaurus guilelmiimperatoris. (H) Meyerasaurus victor. (I) Cryptoclidus eurymerus. (J) Mauriciosaurus fernandezi. All limbs are vertically oriented for display. The dorsal ribs in these skeletal reconstructions have been aesthetically refined and thus differ from the initial versions used to infer ribcage cross-sections. Scale bar equals 1 m. https://doi.org/10.7717/peerj.21146/fig-5
Scatter plot and regression models of the pruned skull-neck dataset. The red curve, green dashed line, and the blue dotted line represent the nonlinear regression model based on a log–logistic (LL) function, the Ordinary Least Squares (OLS) model, and the Phylogenetic Generalized Least Squares (PGLS) model, respectively. Lower values of sample-size corrected Akaike Information Criterion (AICc) and mean per cent prediction error (∣%PE∣) represent better model performance. https://doi.org/10.7717/peerj.21146/fig-8
#Body reconstruction and #size estimation of #plesiosaurs by Ruizhe Jackevan Zhao: peerj.com/articles/21146 in @peerj.bsky.social relevant to #EvolutionaryStudies #MathematicalBiology #Paleontology #Zoology
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