While the prehistoric relatives of crocodilians are generally much more obscure than their
dinosaurian cousins, the mega-crocs are an exception.
Including the famous Deinosuchus and Sarcosuchus, they dwarfed the largest modern crocodilians
and were able to regularly prey upon the contemporary dinosaurs.
However, there were also super-sized crocodilians during the Cenozoic era as well.
The most recent of these was Euthecodon.
Euthecodon is a genus which consists of several closely related crocodilians from Africa.
They ranged from the Early Miocene, about 20 million years ago, to a mere one million
years ago during the Early Pleistocene.
All three species of Euthecodon had long, slender snouts that sloped slight downwards.
While plenty of other crocodilians have slender snouts, Euthecodon’s skull table was also
slender, giving it a unique appearance.
Euthecodon also had scalloped margins between the tooth sockets.
While this feature is unique among crocodilians, Euthecodon’s most striking trait was its
sheer size.
The largest Euthecodon specimen is a skull that is one and a half meters long and is
estimated to have come from an individual with a total length of ten meters.
As large as it was, Euthecodon wasn’t the largest crocodilian alive during the Age of
Mammals.
Other species from the same time were as large or larger, including Rhamphosuchus in Asia
and Purussaurus and Gryposuchus in South America.
However, Euthecodon was the largest crocodilian in Africa at the time, and by the Early Pleistocene
it was the largest crocodilian left on the planet.
It was also perhaps the largest reptile that humanity’s recent ancestors ever glimpsed.
When Euthecodon fossils were first found in Ethiopia during 1920, they were mistakenly
thought to belong to the genus Tomistoma, the same genus as the modern false gharial.
Later in the same year, the discovery of additional fossils in Egypt led to the recognition of
Euthecodon as its own, distinct genus.
Given its initial misclassification as a species of Tomistoma, it is little surprise that Euthecodon
was once thought to be part of the same clade: Gavialoidea.
This clade also includes the true gharial and a number of extinct species.
Gavialoids have long, slender snouts similar to Euthecodon.
However, their similar skulls turned out to be the result of evolutionary convergence.
Instead, Euthecodon was a crocodile in the strictest sense of the word.
While most living crocodiles belong to the genus Crocodylus, Euthecodon belonged to the
clade Osteolaeminae, the only other living branch of true crocodiles.
In addition to some other extinct species, such as Rimasuchus, the modern members of
Osteolaeminae belong to the genera Osteolaemus and Mecistops.
Osteolaemus consist of several species of broad snouted dwarf crocodiles, whose lifestyles
naturally differ considerably from Euthecodon.
Mecistops instead includes the two species of slender-snouted crocodiles, who are the
closest known relatives of Euthecodon.
Unlike the gavialoids, their similar snouts are most likely due to common ancestry.
Unfortunately, Mecistops is critically endangered and poorly studied, so the insights it can
give about its giant cousins are limited.
One area it can aid in understanding Euthecodon is determining what it ate.
Mecistops and other slender-snouted crocodiles are primarily piscivorous, preying upon fish
and aquatic invertebrates.
They excel at catching such creatures due to their long snouts, which increase the range
from which they can strike and produce less drag underwater than the broader snouts of
most other crocodilians.
Therefore, Euthecodon was likely a piscivore as well, though between its size and the fact
that its fossils have been found with those of Mecistops, there would have been a degree
of niche partitioning between them.
While slender snouted crocodiles can’t take down prey as large as most other crocodilians,
adults sometimes also kill birds and small mammals.
With its much greater size.
Euthecodon was likely capable of taking down even larger animals, including humanity’s
ancestors.
Additionally, the snout of the oldest species of Euthecodon, Euthecodon arambourgi, was
relatively shorter, so it is reasonable to assume it was less specialized.
Nevertheless, its snout and teeth were still too slender for it to have been the top predator
of prehistoric Africa’s rivers and lakes.
Instead, it was slightly smaller, but broader snouted species such as Thorbjarnarson's crocodile
who terrorized Africa’s prehistoric megafauna.
Though not an apex predator, Euthecodon was an impressive creature.
Not only was it the last of the mega-crocs, but is also shows just how successful a specialized
piscivore can be, outgrowing its more fearsome contemporaries.
Thank you for watching.
I hope you learned something interesting.
Also, a thank you to Flipped StuG for narrating this video.
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