Think Brachiosaurus, Diplodocus, or Brontosaurus, and you probably picture long necks, long tails, small heads, and four enormous weight-bearing legs. These sauropods, or “lizard-footed” dinosaurs, are known for these features, not to mention their impressive size.
Now picture long hooked spikes protruding from a sauropod neck like a bony mohawk. This is what paleontologist Pablo Gallina and his colleagues recently unearthed from a bed of 139-million-year-old rock in northern Patagonia, Argentina.
Their paper published in the journal Nature calls the dorsal appendages “extremely elongate bifid cervical neural spines that point permanently forward,” which makes them sound even more awesome. Consequently, they named the dinosaur Bajadasaurus pronuspinax: Bajada, in reference to the location of discovery; pronus, Latin for bent over forward; and spinax, Greek for spine. They would have lived between the early to mid-Jurassic and early Cretaceous periods.
Only one of the cervical vertebra was found, along with a nearly complete skull (including a “dermal roof and palatal bones, a braincase, and a nearly complete lower jaw”)—enough for the paleontologists to extrapolate the presence of a whole row of spines arming the length of the head and neck. The Bajadasaurus belongs to a group of sauropods called Dicraeosaurids, distinguished by this unusual punk-rocker morphology.
According to the paper’s abstract, a number of theories have been posited to explain Dicraeosaurids’ dramatic ornamentation: “a support structure for a thermoregulatory sail, a padded crest for display, a dorsal hump acting as fat reservoir, and even as inner cores for dorsal horns” among other courtship and defensive adaptations. It’s very likely that they served more than one of these functions, and also possible that they would vary slightly between specimens depending on a whole range of environmental and social factors.
Gallina’s Bajadasaurus discovery, however, tips the speculation scales in a more definitive direction. The delicate structure and extreme elongation of this fossilized vertebra strongly suggests its role not as a weapon, but as a warning. As in, “Hey T-Rex, my neck is bristling with spikes, which will not taste good and will hurt your face a lot.”
That the neural barbs might also have attracted mates or stored extra fat for the lean season or cooled the gigantic lizard-footed behemoths off on a hot day are all very exciting possibilities. While Gallina and his colleagues continue the hunt for more Bajadasaurus pronuspinax specimens in Patagonia, zoologists and entomologists around the world can look to creatures in their fields for current examples of spiky weaponry and regalia.
Because, as Charles Darwin would remind us, “whilst this planet has gone cycling on…endless forms most beautiful and most wonderful have been, and are being, evolved.”