131-foot (40-meter) reconstruction of Argentinosaurus at the Carmen Funes Municipal Museum in Plaza Huincul, Argentina.
The massive titanosaurs
The word “titanosaur” certainly conjures up images of super massive dinosaurs, and it is the name of the largest land animals to ever live. Titanosaurs are sauropod dinosaurs, and are thought to have replaced others upon the Earth, such as brachiosaurs and diplodocids.
They lived from the late Jurassic Period until the end of the Cretaceous, from 156 million to 65.5 million years ago, and reigned for longer than the amount of time that it has been from when the Cretaceous Period ended until the present day. These are the last great sauropods before the extinction event, and the largest in size.
This is what the Earth looked like when Argentinosuaurs was living in South America, during the late Cretaceous Period.
The Cretaceous Period spanned 145 million to 6.5 million years ago. Argentinosaurus existed during the second half, about 94 to 97 million years ago. As the name implies, this animal lived in South America in what is now Argentina.
South America at the time was disconnected from North America, and located further south than it is now. Large portions of the southern portion of South America, and the northwest of the continent, were shallow seas. Sea levels worldwide were much higher than they are now, as global temperatures were considerably higher.
Fossils that have been recovered for this massive reptile are very incomplete, although enough exists to estimate the size of this animal. Most scientists estimate that Argentinosaurus was between 90 to 115 feet (27 to 34 meters) in length, and weighed between 70 and 90 tons (64 and 82 tonnes).
Mapusaurus fossils suggest that they lived and hunted in packs. These carnivores were large enough to have hunted Argentinosaurus in this manner, in South America, about 95 million years ago.
Was Argentinosaurus hunted?
At the same approximate time that Argentinosaurus walked the Earth, and in the same location, were some of the largest carnivorous dinosaurs to ever exist. Mapusaurus is one of the most massive carnivorous dinosaurs ever, probably reaching at least 40 feet (12 meters) in length, and weighing more than 6.5 tons (5.9 tonnes).
It used to be assumed that large carnivorous dinosaurs lived as lone individuals, although in South America a discovery of many Mapusaurus fossils all in the same place makes for good evidence that they lived together in groups and probably hunted in packs. It has been proposed that this animal may have hunted Argentinosaurus.
Argentinosaurus skeleton on display at the Senckenberg Museum in Frankfurt, Germany.
To see an Argentinosaurus, you’ll have to visit either (1) the Fernbank Museum of Natural History in Atlanta, Georgia, (2) the Carmen Funes Municipal Museum in Plaza Huincul, Argentina, or (3) the Senckenberg Museum in Frankfurt, Germany.
The display in Atlanta depicts a hypothetical encounter between Argentinosaurus and Giganotosaurus. The skeleton measures 117 feet (36 meters) in length.
The display in Argentina features the most massive skeleton on display in the world, measuring 131 feet (40 meters) in length. It also depicts a battle with Giganotosaurus.
Giganotosaurs is a close relative of Mapusaurus. It was originally thought that Giganotosaurus hunted Argentinosaurus, although now it is known that they were separated by time and never met, and that it was Mapusaurus that likely hunted Argentinosaurus.
RED is Amphicoelias, which likely did not really exist. PURPLE is Argentinosaurus, and the others are some of the other largest known sauropods. Image is from Amphicoelias article on Wikipedia.
Possibility of larger titanosaurs
There are a few sauropods that are close or possibly equal to Argentinosaurus in size. They include:
Futalognkosaurus, Puertasaurus, Saurposeidon, Dreadnoughtus, Alamosaurus, Paralititan, Antarctosaurus, Mamenchisaurus, and Notocolossus.
Besides these, there are fossils which in each case do not have strong evidence of authenticity, two purported sauropods that could have been considerably larger than Argentinosaurus if they were real. The problem is that in each case, the fossils were supposedly lost.
The two purported species, which if they are real are the largest land animals ever, have been given the names Bruhathkayosaurus and Amphicoelias. I've heard from paleontologists I've had discussions with on Facebook that most likely neither really existed.
Blue whales reach a maximum of about 110 feet (33.5 meters).
Comparison to a blue whale
The modern blue whale is the largest animal to ever live, and even if Bruhathkayosaurus and/or Amphicoelias were real, the blue whale would still likely hold first place.
The largest blue whales are known to weigh in excess of 200 tons (181 tonnes), and this is approximately the same as the largest of the various estimates for the two might-have-beens. It is more than double the weight estimates for Argentinosaurus.