While most people are familiar with prehistoric predators like Tyrannosaurus
and Smilodon,
there were many other large carnivores throughout Earth’s long history.
Among these was Prestosuchus. While smaller than many of the later theropod dinosaurs,
with a length close to 7 meters, Prestosuchus was one of the largest predators during the Triassic period,
and perhaps the largest land predator had evolved by that point.
Only Fasolasuchus and Saurosuchus are thought to have been as large or larger, and they evolved after Prestosuchus.
Despite its similar appearance, it was not a dinosaur but instead a member of Pseudosuchia,
the clade consisting of reptiles more closely related to crocodilians than to dinosaurs.
Among the most apparent differences from both crocodilians and dinosaurs was its posture.
While there were plenty of quadrupedal dinosaurs, all carnivorous species were bipeds.
On the other hand, Prestosuchus seem to have been quadrupedal. It had long forelimbs
and its strongest leg muscles were those that rotated the limbs, a trait characteristic of quadrupeds.
This condition was not universal among Triassic pseudosuchians.
Others, such as Poposaurus and Postosuchus were bipeds.
Prestosuchus’s limbs also differed from those of crocodilians. Whereas crocodilian limbs are held in a semi-sprawling posture,
Prestosuchus’s limbs were weld in a more erect stance. Like dinosaurs and mammals, this would have made it capable of
of greater speed when running. However, the limbs Prestosuchus and other pseudosuchians weren’t built the same
as those of dinosaurs. The legs of dinosaur attached to the hips from the side. Prestosuchus’s limbs instead attached from
below the hips, in what is referred to as the pillar erect stance.
Still, Prestosuchus had much in common with its modern relatives. Attachment points on its limb bones show that it
shared 13 leg muscles with crocodilians and as well as birds, the other living group archosaurs.
However, it only had 2 muscles in common with crocodilians that were not also present in birds. This shows that while
Prestosuchus was more closely related to crocodilians, it still lacked many of the traits they would evolve later.
Like many other pseudosuchians, Prestosuchus had two rows of bony osteoderms on its back.
These osteoderms were wide and roughly heart shaped.
But as an apex predator, love is not what most of the contemporary fauna would have associated with Prestosuchus.
Its main killing weapon was its large, deep skull. Robust and filled with serrated teeth, its bite would have been devasting.
What is interesting is that between the maxilla and pre maxilla, the boundary of which is after the first four teeth in the
upper jaw, there is a small slit. It appears that this slit allowed movement between these two bones,
though why Prestosuchus evolved this trait is currently unknown.
Notably, one Prestosuchus skull is so well preserved that there is an endocast of its brain. Its shape was remarkably convergent
with those of the later large theropod dinosaurs. The reason for this is that their brains were ancestrally similar.
During the Jurassic period, when dinosaur evolved to replace Prestosuchus and its relatives as the apex predators,
they were under similar evolutionary pressure while possessing brains very similar those of Prestosuchus’s smaller ancestors,
explaining the evolutionary convergence.
There is a misconception that Prestosuchus’s name was meant to mean “fast crocodile.
While the suffix “suchus” does means crocodile and is a common component in pseudosuchian names,
“Presto” was not meant to mean “fast”.
This first half of Prestosuchus’s name is instead in honor of Brazilian paleontologist Vicentino Prestes de Almeida,
who was active in Brazil when Prestosuchus was first found. Brazil is also the only place definitive Prestosuchus fossils
are found. These come from the Santa Maria Formation, specifically from the Dinodontosaurus Assemblage Zone.
Slightly younger parts of this formation contain fossils of some of the earliest known species of dinosaur.
Prestosuchus may consists of more than one species. The type species, and the only definitive one,
is Prestosuchus chiniquensis.
Another species assigned to Prestosuchus, Prestosuchus loricatus, may instead be its own genus.
Like the type species, it is also from the Santa Maria Formation.
Fossils of a possible third species, Prestosuchus nyassicus, have been found in the Tanzanian Manda Formation,
, which is also dated to the Middle Triassic. Prestosuchus nyassicus has usually been considered its own genus,
Stagonosuchus.
Some other Prestosuchus specimens have also been found to possibly lay outside of all current established and proposed
species, suggesting Prestosuchus was once very diverse.
Prestosuchus was part of the clade Loricata, which includes many other large, carnivorous species,
such as Postosuchus and Polonosuchus. Loricata also contains Crocodylomorpha, the larger clade that includes crocodilians.
Prestosuchus belongs to neither Crocodylomorpha nor the other advanced clade, Rauisuchidae,
occupying a basal position within Loricata. ts closet relative were Luperosuchus and Saurosuchus.
They may form a small clade or they may form a series with each other, each of becoming progressively closer to the
more derived loricatans, with Prestosuchus being the most basal of the three.
Therefore, crocodilians and other advanced loricatans may be descended from a species of Prestosuchus.
However, it is hard to establish direct ancestor-descendent relationships in the fossil record.
Even if Prestosuchus was not their direct ancestor, it was at a minimum very closely related to that ancestor
and more derived loricatan species were still very similar to Prestosuchus. Even the most basal crocodylomorphs
still retained many similarities. So, whether or not Prestosuchus was their direct ancestor, its legacy still continues on
through the crocodilians.
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