About Amargasaurus
| Scientific Name (Genus) | Amargasaurus |
| Meaning of Name |
Lizard of La Amarga Canyon
La Amarga Formation [Place name] - saurus (lizard) [Greek] |
| Classification | Saurischia, Sauropodomorpha, Dicraeosauridae |
| Total Length | Approx. 12m |
| Diet | Herbivorous |
| Period | Early Cretaceous (approx. 130 - 120 million years ago) |
| Sub-classification / Species Name | Amargasaurus cazaui |
| Year of Paper Publication | 1991 |
| Genus Name Publication | Salgado, L.; Bonaparte, J. F. (1991). Un nuevo sauropodo Dicraeosauridae, Amargasaurus cazaui gen. et sp. nov., de la Provincia del Neuquén, Argentina. |
The Mystery of the Neck Spines: Horns or a Sail?
The most prominent feature of Amargasaurus is the two rows of neural spines along its neck and back, which could measure over 60cm long. Since their discovery, various hypotheses have been proposed regarding their function, including "weapons to defend against carnivorous dinosaurs," "humps for storing fat," and "sails covered by a membrane."
However, a histological study of the bone tissue published in 2022 refuted the long-held theory of them being "weapons covered in hard keratinous horns (spikes)." Detailed examination of the bone surface revealed a complete absence of the characteristic structures and blood vessel grooves needed to support keratin. While once thought to be defensive weapons, this possibility is now considered highly unlikely.
Instead, evidence was found showing that strong "ligaments" connecting the bones were firmly attached to the inside of the spines. Because of this, the most widely accepted theory today is that a sturdy membrane of skin and ligaments was stretched between the spines, creating a massive "sail." It is believed this sail was used to make the body appear larger to intimidate carnivorous dinosaurs or for communication (display) among their own kind.
What is Bone Histology?
It is a research method that involves slicing fossil bones very thinly and observing their internal structure under a microscope. This allows researchers to learn in detail about the dinosaur's growth rate and what kind of muscles and ligaments were attached around the bone during its life.
Unique Feeding Strategy and Rearing Behavior
Compared to other sauropods like Brachiosaurus, Amargasaurus was smaller and had a shorter neck. Recent studies examining the structure of its skull (inner ear) have shown that they habitually kept their heads close to the ground, pointing downwards.
It has also been revealed that the muscles connecting the back of their head to their neck were extremely powerful. Rather than eating leaves from high trees, it is thought they fed using a unique, powerful method: swinging their thick, strong necks from side to side and downwards to forcefully crop or uproot ferns and other plants close to the ground.
Furthermore, a 2025 study using computer simulations proved that Amargasaurus had very robust hind limb bones and could easily rear up on its hind legs alone. While they usually walked on all fours to eat low-lying plants, in an emergency, they might have reared up on their hind legs and flared their neck "sail" to intimidate carnivorous dinosaurs.
What is Finite Element Analysis (FEA)?
This is a method of dividing the shape of an object into small blocks (elements) on a computer to calculate where and how much stress is applied when a force is exerted. It is used in automobile design, etc., but in paleontology, it is utilized to simulate the strength and movement of dinosaur bones.
Many sauropods that grew to massive sizes developed honeycomb-like cavities inside their neck and back bones to lighten their bodies. However, CT scan investigations have revealed that Amargasaurus bones lacked such complex cavities and had a relatively simple structure.
Because they chose an evolutionary path of a smaller body and shorter neck, there was no need to force their bones to be lighter. Instead, they likely maintained a certain bone weight to stabilize their center of gravity. Among close relatives in the Dicraeosauridae family is "Bajadasaurus," which had terrifying forward-curving spines. Rather than growing giant, they successfully adapted to their environment by evolving unique body shapes and spines.
History of Discovery and Research
Source: Salgado, L.; Bonaparte, J. F. (1991)
Amargasaurus fossils were discovered in February 1984 by an expedition led by the famous Argentine paleontologist Dr. José Bonaparte in the "La Amarga Formation" of Patagonia.
It was geologist Luis Cazau who recognized the paleontological importance of this formation and prompted the excavation. In honor of his immense contribution, the species name "cazaui" was given. Incidentally, the carnivorous dinosaur "Carnotaurus" was also discovered during this 1984 expedition.
The discovered fossil (specimen number: MACN-N 15) was found in an extremely well-preserved state, with bones from part of the skull to the pelvis remaining mostly articulated. As a result, Amargasaurus is one of the most thoroughly understood Cretaceous sauropods. Even after being officially described as a new genus and species in 1991, its true appearance continues to be revealed one after another alongside advancements in research methods.