I didn’t know that gastralia, or “belly ribs”, existed until I saw a team of veterinarians dive a knife into the belly of a Tyrannosaurus rex.

The T. rex wasn’t dead – it was never alive. This specimen was a masterwork of special effects artists and scientists. “Edwina,” as the female T. rex model was called, was 46-feet long, covered in proto-feathers, and looked real enough to blink a half-closed eye at any moment. I say “was,” because after I first gasped at the scale of Edwina lying motionless on a metal stage, a team of veterinarians and scientists sliced it apart.

You can watch them do so on June 7^th as a part of National Geographic Channel’s new special, T. rex Autopsy. (Check back on Thursday for my full review.)

When a human is autopsied, just one set of ribs need to be removed. Pathologists cut into the cartilage with a fancier set of pruning shears and around the breastbone or around the sides of the ribs, removing the entire ribcage. A T. rex has ribs you’d need to cut through to get at its organs too – two sets of them. The gastralia would have run from its sternum to its pubic bone, floating free from the skeleton, putting a bony set of armor over the areas we could still take a gut punch.

Click to enlarge.

Today, belly ribs are rare. We find modern sets only in reptiles like crocodiles and turtles and the “living fossils” that are the tuataras. But we have many fossils of gastralia in dinosaurs belonging to the group Therapoda, which includes Velociraptor (what Jurassic Park said it was showing you), Deinonychus (what Jurassic Park was actually showing you), and of course T. rex.

Watching a veterinarian use bolt cutters to crack through the belly ribs of a latex and fiberglass T. rex got me thinking…about dragons.

The Dragon’s Weakness Disappears

Where do you strike a dragon? The soft underbelly. This famous weak spot has been a part of dragon lore from the legend of Beowulf to J.R.R. Tolkien’s Smaug. Clever Quora user Thomas Snerdley traces the history:

In Tolkien’s beloved Old English poem Beowulf, a slave steals a golden cup from the hoard of a dragon at Earnaness, whereupon the dragon leaves its cave in a rage, burning everything in sight.  (Sound familiar?)  After the aged hero Beowulf broke his sword against the dragon’s invulnerably armored head, his kinsman Wiglaf stabbed his sword into the dragon’s belly, wounding it and enabling Beowulf to strike the death blow with his dagger.

The famous Catholic martyr St George was heralded in legend for slaying a dragon, after shattering his spear against its armor, by driving his sword into the dragon’s underbelly (‘… under the wing where there were no scales.‘)

The Volsunga saga and the Nibelungenleid, two of Tolkien’s inspirations, see Odin advising the hero Sigurd to dig a pit and await the dragon Fafnir whom he slays by stabbing him in the belly with his enchanted sword Gram (sound familiar?).

Margaret the Virgin was said to have escaped being swallowed by Satan in the form of a dragon because her cross burned its belly.

The terrible maiden-eating dragon of Kraków was slain by the Polish peasant Skuba who tricked it into eating sulfur and drinking water which caused its belly to explode.

This establishes a recurring pattern within western European mythology and literature vis a vis dragons’ primary weak spot.

But if dragons, though fictional, could be mapped onto any creature at all, wouldn’t it be something like a dinosaur, a T. rex with wings? Comparing a dragon to a T. rex, or at least a T. rex-like reptilian, isn’t the craziest leap in logic I’ve ever heard (especially if you want to find out how many people a dragon needs to eat every day), but it would mean that dragons’ famously soft underbelly wouldn’t have been quite so soft after all.

A noble warrior hoping to slay a dragon would find that the bones and scales protecting its body from arrows and swords would also be found lining the entire belly – gastralia would make its belly just as hard to pierce as anywhere else. Learning the art of dragon slaying should begin with Dinosaur Anatomy 101.

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Kyle Hill is the Science Editor at Nerdist industries. Follow on Twitter @Sci_Phile.

IMAGE: National Geographic; L.M. Sterling