It’s not just the punk-rocker neck spikes.
Like many artists, Amargasaurus was discovered in the 80s but unappreciated for years. In this case, until Leonardo Salgado and José F. Bonaparte described it in 1991, but this is common in palaeontology and no reflection on its awesomeness.
Breakout artist, or one of many?
There’s only one known Amargasaurus skeleton, and what’s more, it’s South America’s first dicraeosaurid (like a smaller, dumpier Diplodocus). Until then, dicraeosaurs and the armoured titanosaurs, like Malawisaurus, were only known from Africa, both part of the southern supercontinent Gondwana. This had begun to break off from Laurasia in the north, and since these dinos were nowhere to be found up there, it’s thought they made a rapid rush south once the two continents began to split. But while Amargasaurus was part of the same movement, it still had a look all its own.
Cool off, show off, or fend off?
So far no other dinosaur has been found with such elaborate neck spikes, and in two rows no less. They were probably covered in a keratin sheath, but the jury’s still out as to whether they supported a flashy fin for keeping cool and attracting mates, or if the bare spikes were used to backwardly-stab enemies or lock with rivals for wrestling. A rock god needs to do all three (only artistically, one would hope), but it can’t just be about the music.
Sharp notes or dull beats?
Gregory S. Paul suggested the porcupine-esque spikes could even be rattled, either to intimidate foes or impress the opposite sex. However, based on inner ear studies of other sauropods, Amargasaurus’ hearing probably wasn’t great, even without years of concerts shredding its ear drums, so it seems odd for it to rely on sound for courtship. Its hearing wasn’t its only issue either.
Suffering for its art?
Such elaborate spikes meant Amargasaurus couldn’t lift its head higher than about 3 metres (9.8 feet), so both certain foods and the usual “S-shape” neck pose struck by other sauropods was off limits, at least if CT scans and biomechanical modelling are anything to go by!
On the other hand, restriction inspires creativity, and Amargasaurus carved out its own niche by feeding at mid-height, while other sauropods of its time browsed the tree line (titanosaurs) or lower to the ground (rebbachisaurs). Despite the aforementioned dumpiness, its legs were sturdy enough that it could probably charge like a rhino, and this coupled with its spikes must have put on a good show. But all good things come to an end.
Death of a legend
Given that Amargasaurus was smaller and shorter than more ancient sauropods, it may have evolved by paedomorphosis, i.e. by taking on juvenile aspects of its ancestors. But as any old rocker knows, trying to stay forever young doesn’t always pay off.
It missed the decidedly rock-and-roll death of the comet by tens of millions of years, and probably died out from competition with rising stars like the thumb-spiked iguanodontids and other herbivores migrating down from Laurasia.
It might not have gone out in a blaze of glory, but Amargasaurus is a snapshot of another time and place where outrageous spikes, colours, looking young and breaking new ground was all the rage. And calling someone a “dinosaur” didn’t mean they were old.
Meaning: Cazau’s reptile from Amarga (Amargasaurus cazaui), named after geologist Luis Cazau and the La Amarga Formation where it was found
What? Long-necked plant-eating dinosaur with tall neck spikes/a sail
Where? Argentina, 130 million years ago in the Late Jurassic-Early Cretaceous
How big? 2.5 metres / 8.2 feet high, 10 metres / 32 feet long.
Probable motto: I either look cool, keep cool, or both.
Just to prove I’m not fibbing:
“Amargasaurus“. No date. Natural History Museum.
“Amargasaurus“. No date. Western Australian Museum.
“Amargasaurus cazaui“. No date. Melbourne Museum.
Carabajal, Ariana Paulina et al. 2014. “Braincase, neuroanatomy and neck posture of Amargasaurus cazaui (Sauropoda, Dicraeosauridae) and its implications for understanding head posture in sauropods“. Journal of Vertebrate Paleontology 34(4):870-882.
Gregory, Paul S. 1994. “Dinosaur art and restoration notes: Dicraeosaurs“. The Dinosaur Report.
Hallett, Mark, and Wedel, Mathew J. 2016. Life in the age of giants: The sauropod dinosaurs. Johns Hopkins University Press.
Mazzetta, Gerardo V. et al. 2006. “Giants and bizarres: body size of some southern South American Cretaceous dinosaurs“. Historical Biology 16(2-4):71-83.
Novas, Fernando E. 2009. The age of dinosaurs in South America. Indiana University Press.
Sabrina. 2017. “I Know Dino Podcast Show Notes: Armagasaurus (Episode 157)“. IKnowDino.com.
Salgado, Leonardo, and Bonaparte, José F. 1991. “A new dicraeosaurid sauropod, Amargasaurus cazaui gen et sp. nov., from the La Amarga Formation, Neocomian of Nequén Province, Argentina“. Ameghiniana 28(3-4):333-346.
Strauss, Bob. 2017. “Amargasaurus Facts“. ThoughtCo.
Woodruff, D. Cary. 2017. “Nuchal ligament reconstructions in diplodocid sauropods support horizontal neck feeding postures“. Historical Biology 29(3):308-319.
Featured image credit: “Amargasaurus” by Shan Ahmed