While the crocodilians of today are semi-aquatic-carnivores,
the larger group of reptiles they are a part of, Crocodylomorpha, was ancestrally terrestrial.
After the lineage that led to crocodilians split off, some of these terrestrial crocodylomorphs
evolved to become herbivores. One of the first of these planting eating land crocs
found was Chimaerasuchus. Chimaerasuchus lived in China during the Early Cretaceous period, about
120 million years ago. The only known specimen was found in the Wulong Formation during the 1960s,
though it was not until 1995 that it was finally named. Before this Chimaerasuchus was thought
to be a primitive mammal due the incomplete nature of its remains and because it possessed
teeth similar to one. Chimaerasuchus’s basic appearance was fairly standard for land crocs.
It was a small quadruped with legs held directly beneath its body, with a skull
taller and much shorter than most crocodilians. Due the incomplete nature of its remains,
the exact length of Chimaerasuchus is unknown, but it is estimated to have been one meter long.
It is its teeth that gave it its scientific name, Chimaerasuchus paradoxus, which means “strange
chimera crocodile”. Chimaerasuchus was heterodont, meaning it had more than one type of tooth.
While those at the front of the jaw were simple conical incisors, while the rest were multicusped
like in mammals. Indeed, Chimaerasuchus’s teeth were actually better suited for consuming plants
than those of many modern herbivorous mammals. While such complex and varied teeth are common
among mammals, they are rare among reptiles. A ridge found on Chimaerasuchus’s mandible appears
to have been an attachment point for cheeks, which would have helped keep food in while it
chewed. The mammal-like teeth were not the only unusual ones. Two of the front teeth protruded
out of Chimaerasuchus’s snout, giving it a bit of a “buck toothed” appearance. Coincidentally,
another bucked toothed plant eater, the oviraptorosaurian dinosaur Incisivosaurus,
is also known from Early Cretaceous China. In Chimaerasuchus, these buckteeth may have been used
for both biting off plant matter and potentially sparring with rivals of the same species.
Chimaerasuchus’s feet were also tipped with large, curved claws that could have also been used for
interspecific combat. They may have also been used in defense against predators, digging burrows,
or uncovering roots. However, offence would not have been its only option
for dealing with predators. An osteoderm was among Chimaerasuchus’s remains. Osteoderms are
pieces of bone that grow out of the skin, which are used for both mineral reserves and as armor
They are present in the crocodilians of today and were abundant among extinct crocodylomorphs
and other extinct creatures. Discoveries after Chimaerasuchus was found have in some ways
made rather normal while others have made it even stranger. When Chimaerasuchus was first described
in 1995, not many herbivorous crocodylomorphs had been found or properly recognized. The only
two proposed at the time were Malawisuchus, who was not even named at the time, and Notosuchus,
who turned out to be a carnivore. Since then, many other plant-eating crocodylomorphs have been
found. Most of these belong to Notosuchia, the same branch of Crocodylomorpha as Chimaerasuchus.
These include Simosuchus from Late Cretaceous Madagascar and Pakasuchus from mid-Cretaceous
Tanzania. However, herbivory evolved independently in Notosuchia several different times. Combined
with an incomplete skeleton, this means it is uncertain where Chimaerasuchus fits in Notosuchia.
Additionally, while Chimaerasuchus was found in East Asia, most other notosuchians have only been
found in the southern continents. During the Cretaceous period, the fauna of the northern
and southern hemispheres were largely separated. All other northern notosuchians,
such as Ogresuchus, have been found in Europe, which, unlike North America and Asia, was still
close enough to the southern Gondwanan continents for southern species to regularly colonize it.
This makes Chimaerasuchus’s presence in China a very notable exception to the norm.
Therefore, while a plant eating crocodylomorph is no longer so unusual, Chimaerasuchus remains a
very strange little reptile. Thank you for watching. I hope you learned something
interesting. If you enjoyed the video remember to press the like button. Herbivorous crocodylomorph