Amargasaurus: The Spiny Sauropod of the Early Cretaceous

Dinosaur Facts:

• Dinosaur Type: Sauropod (family Dicraeosauridae)
• Period: Early Cretaceous (approximately 130–120 million years ago)
• Diet: Herbivore
• Length: Approximately 30–33 feet (9–10 meters)
• Height: Roughly 7–8 feet (2.2–2.5 meters) at the shoulder; maximum browsing height around 9 feet (2.7 meters)
• Weight: Estimated 2.5 to 4 metric tons (most estimates around 2.6 tons)
• Notable Features: Relatively short neck for a sauropod, and a striking double row of tall, paired neural spines along the neck and shoulders (possibly for display, thermoregulation, or defense)

Amargasaurus for Kids

Meet Amargasaurus! Amargasaurus is a fascinating dinosaur known for the dramatic double row of spines running along its neck and back. This herbivorous dinosaur roamed the floodplains and coastal forests of what is now Argentina during the Early Cretaceous period, munching on plants while sporting one of the most unusual silhouettes of any dinosaur ever discovered.

What did Amargasaurus look like? Unlike its giant long-necked cousins, Amargasaurus actually had a fairly short neck for a sauropod, and it was on the small side — roughly the length of a school bus. Its most striking feature was the double row of tall, paired neural spines running from its neck onto its shoulders. Some scientists think these spines may have been covered in skin to form a sail, while others think they were sheathed in keratin like animal horns.

What did Amargasaurus eat? As a herbivore, Amargasaurus fed on ferns, cycads, conifers, and other low- to mid-height vegetation. Studies of its inner ear and neck bones suggest it usually held its head about 30 inches off the ground, making it more of a low-to-mid browser than a treetop feeder.

In-Depth Look at the Amargasaurus

Anatomy and Physical Features Amargasaurus belongs to the Dicraeosauridae, a family of sauropods that distinguished themselves from giants like Diplodocus and Brachiosaurus by having shorter necks and smaller bodies. What made Amargasaurus truly unique was its vertebrae: each cervical and anterior dorsal vertebra carried two extremely tall, parallel neural spines, with the longest reaching about 60 cm (24 inches). No other known sauropod carried spines this tall in this configuration. Whether they supported a skin sail, a keratin-covered defensive structure, or a fleshy hump (like a bison's) remains an active scientific debate. (source: Discover Magazine).

Behavior and Habitat Amargasaurus lived in what is now Patagonia, Argentina, in an environment reconstructed as well-watered coastal forests and floodplains with a short dry season — not the desert it's sometimes depicted in. It shared this habitat with at least three other sauropod genera, including the rebbachisaurid Zapalasaurus and the dicraeosaurid Amargatitanis, which likely fed at different heights to reduce competition. Living in herds may have provided safety in numbers.

Scientific Discovery and Research The single known Amargasaurus skeleton was discovered in February 1984 by Guillermo Rougier during an expedition led by Argentine paleontologist José Bonaparte in the La Amarga Formation. Salgado and Bonaparte formally described the dinosaur in 1991, naming it Amargasaurus cazaui after the formation and the Argentine geologist Luis Cazau. The specimen is remarkably complete — including a partial skull — making it one of the best-known sauropods of its era despite being represented by just one individual.(source: American Museum of Natural History).

Predators and Defense The predators Amargasaurus actually faced were the small ceratosaur theropod Ligabueino and a larger, unidentified tetanuran known only from teeth — not the famous Late Jurassic Allosaurus of North America, which had gone extinct tens of millions of years earlier on a different continent. The function of Amargasaurus's tall neck spines is debated, but one leading hypothesis is that they made the animal look larger and more threatening to deter exactly these kinds of predators.

Ongoing Research and Discoveries A 2025 study by Mariano Militello and colleagues reconstructed the neck musculature of Amargasaurus, finding evidence of unusually mobile head movement that would have helped it graze and uproot low vegetation across a wide feeding area without moving its body. The discovery of a close relative, Bajadasaurus, in 2019 — with similar but forward-curving spines — has reignited debate about how dicraeosaurids used these structures, and whether the spines were defensive, display-oriented, or both.

Amargasaurus in Popular Culture Amargasaurus's bizarre silhouette has made it a favorite of paleo-artists, documentaries, and video games (most recently Jurassic World Evolution). Its dramatic spine arrangement makes it instantly recognizable and ensures it stands out in any prehistoric lineup. (source: Ancient Origins).

Conclusion Amargasaurus stands out as one of the most distinctive dinosaurs ever discovered. As a small, short-necked, low-browsing sauropod sporting a double row of towering spines, it challenges the stereotype of what a sauropod "should" look like — and offers a vivid window into the surprising diversity of plant-eating giants that roamed Early Cretaceous South America.