Discovered 'vampire fish' with bizarre teeth

The 45 million-year-old fossil in Pakistan reveals an unprecedented history of a fish with only one tooth in its upper jaw.

The tooth structure of this ancient creature was so special that scientists decided to name it Monosmilus chureloides . "Monosmilus" means a sword tooth, while "chureloides" refers to a vampire-like demon with long fangs in the folklore of several South Asian countries, including Pakistan, where the fossils be excavated.

Graphics that simulate a Monosmilus chureloides attacked by predators. (Photo: Joschua Knüppe)

As described, M. chureloides is about a meter long when growing up. They lived 45 million years ago in the shallow waters of Pakistan, at the same time and place with some 4-legged whales like Dalanistes.

Fossil analysis showed that the creature had only a single tooth in the upper jaw like a sword tooth. Meanwhile, the lower jaw has up to 16 fangs tapering back; the largest one is 2cm long, about 20% of the head length, according to Alessio Capobianco, lead author of the study from the University of Michigan, USA.

The tooth structure and head bone of M. chureloides. (Photo: Novataxa).

"When closed, the maxillary teeth extend from the tip of the mouth to the bottom of the chin. It is difficult to explain its purpose exactly. No fish, living or extinct, has a similar tooth structure." " , Emphasized Capobianco. "M. chureloides can use this sword tooth as a trap, like today's deep sea fish, or use it to stab other fish."

The only fossil of M. chureloides was excavated in 1977 by an expedition team from the University of Michigan and Pakistan's Geological Survey, but it has only recently been examined.

Anatomical analysis shows that this "vampire fish" is closely related to today's anchovies. "It was a big surprise, because all the anchovies were much smaller than M. chureloides. Most ate only plankton and had very small teeth , " Capobianco explained.

The study details were published in the May 13 issue of the journal Royal Society Open Science .