Ca12 - Spinosaurus aegyptiacus neotype

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12th caudal vertebra of the Spinosaurus aegyptiacus neotype, FSAC-KK 11888.

Ca12 is peculiar because it preserves an incomplete, very thin prespinal lamina, located dorsally to the centrum and connecting the prezygapophyses to the spine. The prespinal lamina forms a prominent median buttress which, together with the spinodiapophyseal laminae and postspinal lamina, served as the attachment site for the interspinous ligaments. Distal to the transition point (Ca19) the prespinal lamina is only very weakly expressed and then disappears.

From Ca11–12 on, throughout the caudal series, the neural spine becomes more inclined at the base, maintaining a remarkably constant angle of 45°.

The specimen is housed in the palaeontological collections of the Université Hassan II, Aïn Chock, Casablanca, Morocco.

Reference: Ibrahim N. et al. (2020). Tail-propelled aquatic locomotion in a theropod dinosaur. Nature, doi.org/10.1038/s41586-020-2190-3.