Throughout prehistory, there were a variety of reptiles closely related to crocodilians,
referred to as crocodylomorphs. Perhaps one of the strangest, and cutest, was Simosuchus
clarki, a small herbivorous, pug nosed crocodylomorph. Simosuchus was a member of Notosuchia, a clade
of terrestrial crocodylomorphs that were common in the southern hemisphere during the latter
half of the Mesozoic era. Simosuchus’s fossils are from the Maevarano Formation in Madagascar,
which was formed during the very end of the Late Cretaceous period. Named in the year
2000, its genus name translates to “pug nosed crocodile”, in reference to how its
blunt snout resembles that of a pug. Its species name, clarki, is in honor of paleontologist
James M. Clark for his research into the evolutionary relationships of crocodylomorphs. Between
various specimens, Simosuchus’s anatomy is rather well known. Overall, it looked like
a combination of a crocodile, an ankylosaur, and a pug. Since it was the product of natural
selection rather than the sick whims of primates, it could breathe properly. Like pugs, its
body was broad, compact, and small. Simosuchus was only 0.75 meters long, in part because
its stocky tail was proportionally shorter than in most other crocodylomorphs. Simosuchus’s
namesake feature, its pug-like head, was short and wide. It bore various bony ornamentations
which, given the variation within specimens, are thought to have been used for display.
While named after pugs, its short, broad skull was in many ways more similar to those of
ankylosaurid dinosaurs. Among herbivores, such broad snouts are indicative of non-selective
feeders who eat large amounts of poor-quality foliage, as opposed to those with narrow snouts,
who are more selective in what vegetation they eat. Simosuchus is known to be a herbivore
due to its clove shaped teeth, which are similar to those of herbivorous ankylosaurs and are
well adapted for griding up plant matter. While short, the legs of Simosuchus were robust
compared to those of other crocodylomorphs, with attachment points for strong leg muscles.
The legs of Simosuchus’s legs were held in a semi-erect position. While this is not
that different from modern crocodilians, the legs of most other notosuchians were fully
erect. Simosuchus’s forelimbs were also longer than the hind limbs, which may have
helped it to browse higher foliage than would have otherwise been available. Likewise, the
forefeet were also larger than the hindfeet. Tipped with large claws, these may have been
potent weapons against predators. Its strong, robust claws and limbs were also conductive
for digging, as was its shovel shaped head, which had attachment points for powerful neck
muscles. Digging would have allowed it to both find roots and to create burrows. Such
burrows would have provided safety from predators and have aided in thermoregulation like in
modern crocodilians. However, its primary defense was likely its extensive armor. Like
crocodilians and ankylosaurs, its body was covered by osteoderms, bony tissue attacked
to the skin. While osteoderms are a common trait in crocodylomorphs, the extent of the
armor in Simosuchus was far greater than normal, closer to that of ankylosaurs and aetosaurs.
The osteoderms encased its back, belly, and tail. Even its limbs had extensive amounts
of armor, highly unusual for a crocodylomorph and likely why it reverted to a semi-sprawling
gait. Simosuchus was far from the only notosuchian that was a herbivore. Planet eating notosuchians
were fairly common during the Cretaceous period, especially in the south. These included Armadillosuchus.
Chimaerasuchus, and Pakasuchus. Simosuchus itself differs considerably from other notouschians.
Even the skull has 45 unique features. The only fossils of a similar notosuchian are
from limited in India. The reason Simosuchus is so unique is due to its biogeography. While
the continents had been united at the start of the Mesozoic era, by the time Simosuchus
was alive, 67 million years ago, Madagascar had been separated from the rest of the world
for over 20 million years, giving it a long time to evolve in isolation. Even though they
lived at the same time, Simosuchus would have never seen Tyrannosaurus rex, Triceratops,
or the other classic dinosaurs that lived in North America at the very end of the Cretaceous
period. As India was the last landmass to break away from Madagascar, it is little surprise
that it is the only location with fossils of a Simosuchus-like species. During this
time, Madagascar was a highly seasonal flood plain, shifting from swamps to a semi-arid
climate throughout the year. Among the fossils found at the Maevarano Formation are teeth
of what may have been an ankylosaur, meaning that Simosuchus possibly lived alongside a
member of the group it was so convergent with. Other fauna Simosuchus coexisted with included
the titanosaur sauropod Rapetosaurus, the giant horned frog Beelzebufo, the small theropod
Masiakasaurus, the fellow crocodylomorphs Araripesuchus tsangatsangana and Miadanasuchus,
and of course the apex predator Majungasaurus. The isolation of Simosuchus’s native Madagascar
produced a bizarre and unique fauna, which remains true today due to its continued isolation.
In this regard, Simosuchus was right at home. Overall, despite its small size, Simosuchus
clarki was an amazing creature and one that showed the impressive diversity of Crocodylomorpha.
Thank you for watching. I hope you learned something interesting. Have a great day and,
if you enjoyed the video, please remember to press the like button.