(ORDO NEWS) — Researchers have discovered a broken tooth from one of the largest carnivores to ever stalk the Earth.
No, this is not a T. rex. It’s not even a dinosaur. Rather, the tooth belongs to a rare and mysterious species of giant ichthyosaur, a carnivorous marine reptile that patrolled the seas during the late Triassic period, about 205 million years ago.
Although the crown of the tooth is partially missing, the root of the fossil canine tooth is twice as wide as any other known ichthyosaur tooth, according to a new study published April 28 in the Journal of Vertebrate Paleontology.
The previous record holder for the largest tooth was an ichthyosaur nearly 50 feet (15 meters) long, the study authors say, possibly making the owner of this newly described tooth one of the largest animals ever to have lived on land or in the sea.
However, because scientists only have half a tooth, it’s impossible to tell if the ancient marine reptile was a real leviathan or just one of the many sea monsters of similar size that ruled the seas of the Triassic period, the researchers say.
“It is difficult to tell whether this tooth belongs to a large ichthyosaur with giant teeth or a giant ichthyosaur with medium teeth,” study lead author P. Martin Sander of the University of Bonn in Germany said in a statement.
Monsters of the Deep
Ichthyosaurs, whose name translates as “fish lizards”, appeared in the middle Triassic period (approximately 252-201 million years ago) shortly after the Permian extinction wiped out approximately 95% of life in the Earth’s oceans.
These aquatic reptiles thrive in the changing seas; in about 5 million years after their first appearance, ichthyosaurs swelled to enormous sizes and dominated all the world’s oceans, the study authors write.
The largest known ichthyosaur, Shastasaurus sikanniensis, is a whale-like creature up to 69 feet (21 m) long, possibly longer.
By comparison, modern blue whales are typically 80 to 100 feet (24 to 30 m) long, while the predatory king T. rex has averaged 40 feet (12 m) in length, according to the American Museum of Natural History.
Many large ichthyosaurs, including the giant Shastasaurus, seem to have become better predators without evolved teeth, the researchers say. Only one species of giant ichthyosaur, a 50-foot Himalayan saurus found in Tibet, is known to have had a full mouth of teeth.
So when scientists discovered a single large ichthyosaur fossil tooth in the Kössen Formation in the Swiss Alps, a 9,200-foot (2,800 m) rock formation that existed on the seafloor of the Triassic period, they were faced with a mystery.
In a new study, scientists analyzed in detail this fossil tooth, as well as several large ichthyosaur ribs and vertebrae found in an alpine formation between 1976 and 1990. The team compared the sample of bones to other giant ichthyosaur fossils with more complete skeletons to gauge the size and appearance of the new specimens.
About 2.3 inches (60 mm) wide at the root and 4 inches (100 mm) high from the root to the broken end of the crown, the fossil tooth is twice as wide as any known Himalayan saurus tooth, the researchers said.
The unique pattern of dentin – the hard tissue that makes up the bulk of reptile and mammalian teeth – proves that the tooth belonged to an ichthyosaur, but the unusual size of the fossil does not match any known species.
If the body of the creature was significantly larger than that of the Himalayan saurus, as indicated by the tooth, then the researchers may be facing the largest ichthyosaur ever discovered.
The ribs and vertebrae from the Kössen Formation are among the largest ichthyosaur fossils ever found in Europe, the researchers say. The tooth, ribs and vertebrae belong to three different ichthyosaurs – and they are all gigantic.
“These giant ichthyosaurs of the late Triassic period were among the largest animals ever to inhabit our planet,” the researchers write.
However, given that only a few bones remain from each specimen, it is impossible to reliably attribute them to a particular species.
Measurements of the bones may also be somewhat skewed, as some of the fossils appear to have been crushed by the movement of tectonic plates that have lifted the Alps out of the sea for hundreds of millions of years, the team noted.
So far, the researchers have assigned three specimens to the Shastasauridae family, the same family as the giants Shastasaurus, Shonisaurus and Himalayasaurus. Whether these specimens are dwarfed in comparison to other goliath sea monsters cannot be resolved without more fossil evidence.
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