While the Mesozoic era was filled with large carnivorous dinosaurs, very few of these predators
were close to the size of Tyrannosaurus rex. Even fewer were as large or potentially larger.
Well known examples are Spinosaurus, Giganotosaurus, Carcharodontosaurus and, to a lesser extent,
Mapusaurus. However, there is one other theropod, that while much more obscure than even Mapusaurus,
also potentially rivaled the tyrant king in size. Its name is Tyrannotitan. Tyrannotitan
was first found in 2005 in Argentina. Besides numerous isolated teeth, it is only known
from two incomplete specimens. From these, it is estimated to have been between 11 to
13 meters long with a weight between 5 to 7 metric tons. Tyrannotitan lived during the
Early Cretaceous, specifically during the Albian stage, which was lasted from 113 to
100 million years ago. Despite the name, Tyrannotitan was not a close relative of Tyrannosaurus.
Instead, it was a carcharodontosaurid, the same clade that also includes the fellow mega
predators Carcharodontosaurus, Acrocanthosaurus, Giganotosaurus, and Mapusaurus, as well as
smaller species including Siamraptor and Concavenator. Tyrannotitan was most closely related to the
fellow South American carcharodontosaurids Giganotosaurus and Mapusaurus, forming the
smaller clade Giganotosaurini. All three were found in Argentina at slightly different times.
Given the massive territory required by such massive predators, it is doubtful a continent
could support more than one of these species at a time. Therefore, it is possible the giganotosaurines
may represent a single linage changing over millions of years. As Tyrannotitan was both
the most basal and the oldest giganotosaurine, it may very well have been the direct ancestor
of its later, more famous relatives. In most regards, Tyrannotitan was similar to the other
large carcharodontosaurids, though it had its own unique traits as well. The most striking
feature of carcharodontosaurids were their deep skulls, which were massive even in proportion
to their bodies. Their skulls were thinner and less robust than Tyrannosaurus’s, resulting
in a weaker bite force. This was remedied by their teeth. Like their skulls, they looked
broad from the side but thin when viewed from the front. They were lined with serrations
that made them excellent at slicing through flesh. In comparison to the other mega-carcharodontosaurids,
Tyrannotitan’s teeth were thicker and straighter. The vertebrae in the hips and tail of most
other giganotosaurines were pneumatic, or hollow, which reduced their overall weight.
Tyrannotitan lacked this trait, which would have made its tail heavier compared to its
relatives. The neural spines of its tail vertebra were also much taller than normal, perhaps
to support the larger muscles needed to support the heavier tail. The neural spines along
the back were also taller than in Giganotosaurus, giving its back a slightly more curved appearance.
The arms of the other large carcharodontosaurids were smaller than most theropods. Like in
the tyrannosaurids, this would have allowed their head to become larger without becoming
too top heavy. Unlike the tyrannosaurids, they were still large enough to imply they
still an important role when hunting. In contrast, and perhaps appropriately for a species that
also has “tyrant” in its name, Tyrannotitan’s arms were smaller than in its relatives. Paradoxically,
Tyrannotitan’s arm muscles also seem to have more powerful, not less. Either way,
Tyrannotitan’s teeth were still its primary weapons. While small sauropods, and juveniles
of larger species, would not have been a problem for most large theropods, Tyrannotitan lived
alongside Patagotitan. With an estimated weight of 55 metric tons, it is one of the known
largest sauropods. Patagotitan has even been suggested to have been larger than Argentinosaurus,
usually considered to be the largest sauropod, though this is still under debate due to a
lack of complete skeletons of either species. Regardless, an adult Patagotitan would have
been too great a challenge for most carnivores. However, carcharodontosaurids like Tyrannotitan
seem to have specialized in such gigantic prey. Rather than kill them in one quick attack,
they are thought to have used their razor sharp, flesh cutting teeth to wound the sauropod
over and over again until it finally died from blood loss or infection. Tyrannotitan
may not have even waited for its prey to die before eating. By slicing off parts of its
flesh during these attacks, Tyrannotitan could feed without necessarily killing its prey.
This strategy, called “flesh grazing”, would partially useful since it may have taken
a long time for a Tyrannotitan to actually kill such an adult Patagotitan. It is possible
Tyrannotitan was a pack hunter. Fossils of the at least seven individuals of the giganotosaurine
Mapusaurus have been found in a single bone bed, which some paleontologists have interpreted
as a pack. While it would normally be difficult for an entire pack of large predators to sustain
themselves, especially when they are contenders for the title of largest terrestrial carnivore,
sauropods the size of Patagotitan or Argentinosaurus would have provided more than enough meat
to satisfy such a group. As Tyrannotitan as closely related to Mapusaurus, it may have
lived in groups as well. Another possibility is that rather than rather than hunt in packs,
Tyrannotitan instead usually lived alone but came together to form temporary mobs to take
down massive sauropods like Patagotitan. This would provide a best of both worlds scenario,
allowing to Tyrannotitan hunt smaller prey without overtaxing the ecosystem while also
providing it access to the rarer giants. Or it could simply be that Tyrannotitan did not
hunt adult Patagotitan, instead preying upon large juveniles, albeit far larger juveniles
than almost any other theropod could even hope to bring down. When Tyrannotitan was
alive, Argentina was a humid floodplain. Besides Patagotitan, not much is known about the fauna
contemporaneous with Tyrannotitan. The few other species known from Argentina during
the Albian stage include smaller sauropods, the primitive ceratosaur Genyodectes, and
terrestrial crocodilian relatives called peirosaurids. Finally, there are the questions of whether
Tyrannotitan was larger than Tyrannosaurs and whether it was the largest theropod. Unfortunately,
since Tyrannotitan is only known from incomplete remains, it is difficult to estimate its exact
size. The same goes for the other mega-carcharodontosaurids and Spinosaurus, though available fossils
suggest Giganotosaurus has the best chance of being the largest carcharodontosaurid.
However, out of the largest theropods, only Tyrannosaurus is known from complete enough
remains to given a reliable size estimate. As mentioned before, Tyrannotitan is estimated
to have been 11 to 13 meters long. The upper estimate is comparable to the upper length
of the largest two Tyrannosaurus specimens, Sue and Scotty. On the other hand, Tyrannotitan’s
weight is thought to have been between 5 to 7 metric tons while Scotty is estimated to
have weighed 8.8 tons. However, Scotty and Sue were exceptional. Most adult Tyrannosaurus
are only thought to have weighed between 5.4 to 8 tons. As Tyrannotitan is only known from
two specimens, it is currently impossible to know how representative these two were
of the species as a whole. Assuming the two known Tyrannotitan specimens were close to
the standard, it seems the average Tyrannotitan was longer than Tyrannosaurus but weighed
less. Regardless of which had the larger average size, it does seem there was overlap between
the two as well as the other mega-predators. Whether or not it was a record breaker, Tyrannotitan
was certainly one of the massive terrestrial predators than ever lived and was the most
dangerous predator in South America during the Albian stage of the Cretaceous. Thank
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