Most bone experts would be surprised to learn that in spite of the enormous size of the dinosaur bones, the largest dinosaur has teeth that are a mere tenth of the size of the largest carnivore teeth. In most cases, when it comes to the teeth of dinosaurs, it is the large carnivores (the ones that are larger than any dinosaurs that ever lived) that have the largest teeth and jaws. But the main question is what dinosaur has 500 teeth? Nigersaurus is the answer. Nigersaurus is the name given to an entirely new genus of dinosaur.
It was first recognized as a separate species (Nigersaurus caboverdensis) by Sheppard in 1930. It was found in late Campanian (mid-late Maastrichtian) rock in Australia’s Kimberley region, about 60 km east of the River Torrens. The bones of the Nigersaurus were collected by the Kimberley Geological Survey in the early 1920s, in the early part of the Kimberley region. This area is now part of the state of Western Australia. Originally it was thought to be a member of the Dromaeosauridae. The bones were separated into a few species (such as Inpexaurus and Nigersaurus). Since that time, more than twenty bones belonging to other species have been recovered.
Few Things About Nigersaurus
Nigersaurus is an extremely large and robust plant eater – a super predator that has more in common with the modern cats than a true carnivore. It is estimated to have weighed up to 8,000 kilograms, and when standing, the whole body would have been one meter long. The fossilized skull that has been uncovered is about 4.2 meters long. It has extremely long snouts, measuring up to 2 meters, and long, slender, snake-like front limbs. It has extremely elongated skull bones. But most striking is its rather odd tooth count.
The molars were extremely sharp and needle-like – almost needle-shaped. One tooth was also missing, leaving the upper jaw shorter. In terms of its skull anatomy, the extreme elongation of its jaw bone and long, slender front limbs are typical of other dinosaurs such as Brusapherosaurus and Ledumahadi mafube. Another similarity is that the bones of the lower jaw connect behind the eye socket. It is thought this was done by a tendon that connects the jaw to the brain. This, combined with the rest of the bones of the skull and neck, led the specimen to be assigned to the genus Nigersaurus.
Curiously, Nigersaurus is more distantly related to most diplodocoids theropodous dinosaurs. It is more closely related to the another dinosaur of similar size that lived around the same time: Leaellynasaura. The reason for this is not known, but it could be down to ecological differences. Nigersaurus comes from the oldest Jurassic of Australia. Other theropodous dinosaurs like Leaellynasaura lived in the earlier Cretaceous. And because both diplodocoids existed on the same time scale, the theory is that the two groups may have been a different grouping of dinosaurs.
What the Scientific Committee on the Dinosaur Record Really Said
The scientific committee on the dinosaur record have no official position on whether Nigersaurus is a dinosaur or not. In their report they state:
“An unusual tooth (top of page) has been described from a specimen of Nigersaurus caboverdensis, a Theropods. The tooth is very similar to a tooth from Sauroposeidon and therefore it has been suggested that this individual may represent a spurling” (sic). This “spurling” refers to the characteristic “sail” of the tooth which is at the front of the tooth below the crown (the uppermost part of the tooth).” (sic)
This “Theropods” may well be another Theropods (some think it may be a sub-species of Dromaeosaurus). But the nature of the tooth in question is very unlike any theropod tooth known. It was previously thought that this “spurling” was a growth sign. However, this is not the case. It is in fact a pathological anomaly that is unique to Nigersaurus, and even other pachycephalosaurs. This anomaly suggests that the bones of the “protrusion” of the tooth are truly that of a dinosaur, or, at the very least, that Nigersaurus is an ancient ornithischian.
If it is a Theropods tooth, and the tissue is still present, it could be true dinosaur material. This would of course be of huge importance in how we look at the origin of pachycephalosaurs. Theropods – which included Tyrannosaurus Rex and Velociraptor – are the top carnivores on Earth and were the top predators at the time. If we were to accept that Nigersaurus is a dinosaur, it would put the origins of pachycephalosaurs – and the theropods – back in the Jurassic, as they are typically thought to have appeared.
