Introduction
Argentinosaurus is a land animal that boasts one of the largest masses in the history of animals discovered so far (including extinct and extant species).
As sauropods, Jurassic Brachiosaurus and Diplodocus are famous, but Argentinosaurus is a dinosaur that lived in the Cretaceous period. In recent studies, it has attracted attention from paleontologists around the world as a representative dinosaur showing the "extreme gigantism" reached by sauropods.
About Argentinosaurus
| Scientific Name (Genus) | Argentinosaurus |
| Meaning of Name |
Argentine lizard
Argentina (country name) - saurus (lizard) [Greek] |
| Classification | Saurischia, Sauropodomorpha, Titanosauria |
| Total Length | Max over 35m |
| Weight | About 65-75 tons (About 70 tons in recent studies) |
| Diet | Herbivorous |
| Period | Late Cretaceous (Cenomanian - Turonian: approx. 97 - 93.5 million years ago) |
| Sub-classification / Species Name | Argentinosaurus huinculensis |
| Year of Paper Publication | 1993 |
| Genus Name Publication | Bonaparte, J.F. and Coria, R.A. (1993). Un neuvo y gigantesco Saurópodo Titanosaurio de la Formación Río Limay (Albiano-Cenomaniano) de la Provincia del Neuquén, Argentina. |
Argentinosaurus - Giant Body and Its Features
Argentinosaurus is famous as one of the largest land animals in history, but surprisingly, the fossils found so far are very fragmentary, such as a backbone (dorsal vertebra), a shin bone (fibula), and parts of foot bones. There is only one backbone, which is about 1.5 meters high, and the length of the first shin bone found reached 155 centimeters.
Since there is no complete skeleton, what it looked like is estimated by comparing it with closely related dinosaurs with more fossils found (such as Patagotitan).
Secret of the skeleton supporting the giant body
To protect the extraordinary weight of about 70 tons from gravity, the backbone of Argentinosaurus had a special device. In the joints of some backbones, there were accessory joints (spare joints) called "hyposphene-hypantrum", which functioned as a "locking mechanism" to prevent the bones from twisting or shifting excessively. It possessed a strong structure like a "arch bridge" suspending huge internal organs.
In the past, some scholars thought, "Maybe its body was too big to walk on land, and it lived in the water." However, recent simulation technology using supercomputers and physics has proven that they walked excellently on land.
A study using the latest physics simulation (a model of an animal swinging its legs like a pendulum) published in 2025 revealed that their "preferred walking speed" to save the most energy was about 5.2 - 5.7 km/h (about 1.45 - 1.58 m/s). This is about the same speed as a modern large horse (draft horse) walking without a load or a human walking briskly.
The debate over the world's largest dinosaur
Since the 2000s, new giant dinosaurs such as "Puertasaurus" and "Patagotitan", which were thought to potentially surpass Argentinosaurus in size, have been discovered one after another in South America.
However, comparative studies based on rigorous volumetric calculations in recent years have proven that Argentinosaurus was about 25% (one quarter) heavier than Patagotitan, which was considered a rival. Even now, Argentinosaurus holds an unshakable position as the "scientifically proven largest dinosaur".
Limit of gigantism and the latest weight estimation
Accurately estimating the body length and weight of Argentinosaurus has been a major challenge in paleontology for many years.
In early research (1990s - 2000s), simple methods were used, such as plugging the thickness and length of the found leg bones into formulas or expanding the proportions of other sauropods like Brachiosaurus. Therefore, the weight estimates varied widely from 65 tons to 100 tons.
Conclusion by the latest technology "Volumetric Modeling"
In recent years, instead of relying only on bone thickness, a very precise method called "volumetric modeling" has been introduced. This method connects the entire skeleton in a natural posture on a computer, restores the fleshiness (volume) when it was alive, and multiplies it by the density of living animals.
As a result of analysis using this rigorous model, it was calculated that the weight of Argentinosaurus was about 70 tons (in the range of 65-75 tons), and the total length was a maximum of over 35 meters. This latest data is far more reliable than older formulas and serves as scientific evidence to correct media exaggeration.
Astounding growth and the ecosystem of the time
The hint as to why they were able to grow so huge was hidden "inside the bones". Observing the fossil bones at a microscopic level reveals that their bones were concentrated with blood vessels, and they had a mechanism unique to modern birds and mammals, where old bone is quickly replaced by new bone.
This indicates that they were not sluggish poikilotherms (cold-blooded animals), but animals with a highly active metabolism. Argentinosaurus, hatched from an egg the size of a beach ball, is thought to have grown at an explosive speed, increasing its weight by tens of thousands of times in just a few decades.
Why was there a need to grow so fast? It was because a terrifying carnivorous dinosaur called "Mapusaurus", reaching 10-12 meters in length, lived in packs in the same environment. Juveniles and young individuals of Argentinosaurus were constantly targeted by Mapusaurus, so they adopted a survival strategy to grow into a giant body that natural enemies could not touch as soon as possible.
The Patagonia region (a stratum called the Huincul Formation) where they lived about 95 million years ago was a semi-arid climate with dry and rainy seasons, and an environment where rivers flowed like a net. Along the rivers, there were rich forests of conifers and ferns, and Argentinosaurus used its towering long neck to eat large amounts of leaves from high trees that other herbivorous dinosaurs could not reach.
Fossil Discovery and Paper Description
Source: Bonaparte, J.F. and Coria, R.A. (1993).
The bones of Argentinosaurus first came to human eyes in 1987. They were discovered by a farm worker, Mr. Guillermo Heredia, on a farm in Neuquén Province, Argentina, South America. Initially, the extraordinary object protruding from the ground was mistaken for "giant petrified wood" rather than a dinosaur bone.
Later, fossils recovered by museum staff turned out to be those of a giant dinosaur, and a large-scale scientific excavation project began in early 1989.
The excavated specimens were studied in detail, and in 1993, a paper was officially published as a new genus and species of dinosaur, "Argentinosaurus huinculensis", co-authored by prominent Argentine paleontologists Dr. José F. Bonaparte and Dr. Rodolfo A. Coria.
This historic discovery became a major turning point, confirming that the South American continent was the stage for the evolution of the world's largest land animals in the Cretaceous period.
Argentinosaurus Stamp and Fossil Gallery
