Paper Published on Crocodile with Mammal-like Teeth
Scientists writing in the journal “Nature” have reported on their research into a strange and bizarre cat-sized crocodile that filled a particular niche in the dinosaur dominated Cretaceous ecosystem. The teeth of this particular reptile are similar to those seen in mammals and indicate that this little animal could bite and chew its food – a behaviour not seen in extant Crocodilians.
Palaeontologists unearthed an almost complete specimen in 2008, since then a number of other fossils of this 100-million-year-old creature have been found at a dig site in southwestern Tanzania. No bigger than a domestic cat, this agile reptile scampered around the undergrowth chasing insects and small mammals whilst trying to avoid the attention of larger carnivorous dinosaurs that it shared its flood plain environment with.
Researcher Patrick O’Connor of Ohio University commented on the crocodile’s most striking feature, its teeth stating:
“If someone were just to describe those teeth, the shapes and how they interact with one another or work together, most people would read that as a very mammalian-like dental series.”
The scientist went on to discuss the latest discovery, an intact skull, complete with sharp incisors at the front of the jaws – ideal for tearing meat and interlocking upper and lower molars at the back of the jaw that were used for grinding, just like the teeth in the back of our own jaws.
The crocodile has been formally described and named Pakasuchus kapilimai. The name means “Cat Crocodile”, from Paka the word for cat in the Swahili language and Suchus coming from the Greek word for crocodile. A CT scan of this long-limbed terrestrial animal revealed that the molar-like teeth in the top and bottom jaws met very accurately when the animal bit down. The creature would have eaten with a chewing action, mobile jaws in Reptilia are almost unknown (until now).
An Illustration of Pakasuchus kapilimai
Picture Credit: Mark Witton (University of Portsmouth)
The teeth of modern crocodiles are relatively simple in contrast to Pakasuchus kapilimai. All the extant species of Crocodilian have sharp, pointed conical teeth, the teeth (known as the dentition), may vary in size and angle but they are all virtually the same shape, with the same function to grab and hold onto prey. Modern crocodiles cannot chew their food, they twist their bodies (known as a crocodile roll) and tear of chunks of flesh from their victims, these pieces are then swallowed whole.
Paul Filmer, Programme Director of Geology and Palaeobiology at the U.S. National Science Foundation, which co-funded the expedition with the National Geographic Society commented:
“The Crocodilians with which you and I are familiar have a very characteristic smile, as it were. The teeth or the dentition that they have is mainly a row of conical teeth which may vary a little bit in size and angle, but they’re pretty much all the same and they basically serve that function which is to grab and tear.”
Scientists say modern crocodiles did not evolve from the prehistoric crocodile-like creature that was a species of ancient reptiles called Notosuchians Crocodyliform that died out around the same time that other land-dwelling dinosaurs became extinct.
Paleontologists say Notosuchians are characterised by a variety of different tooth structures and patterns.
Researcher Patrick O’Connor says the 100-million-year-old reptiles, which flourished across a southern landmass the predated the African continent, probably filled a unique ecological niche.
“Maybe there was a certain place in the ecology or in the environment where these animals lived that allowed them to experiment with the shape of the teeth. And as evolution works, if that was a successful experiment, then a group could go on and have a very long history.”
The Crocodilians have evolved into a myriad of forms over their long evolutionary history to read an article about unusual crocodile-like animals: Five “Oddball” Crocodiles from the Mesozoic