Gastralia

: gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods.

These structures have been referred to as inscriptional ribs,[2] based on their alleged association with the inscriptiones tendinae (the tendons that form the six pack in humans).

[2] Gastralia are also present in a variety of extinct animals, including theropod and prosauropod dinosaurs, pterosaurs, plesiosaurs, choristoderes and some primitive pelycosaurs.

[3][4] Discoveries about how the gastralia fit together in the skeleton of Sue the T. rex have led to an understanding that Tyrannosaurus bodies were more barrel-chested – and heavier – than previously thought.

[13] The Allosaurus fragilis specimen USNM 8367 contained several gastralia which preserve evidence of healed fractures near their middle.

[15] The left scapula and fibula of an Allosaurus fragilis specimen catalogued as USNM 4734 are both pathological, both probably due to healed fractures.

[16] The holotype of Neovenator salerii had many pathologies, including pseudoarthrotic gastralia and a deviation to the right of the third and fourth neural spines of the neck vertebrae.