- News Home
6 March 2014 1:04 pm ,
Vol. 343 ,
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
- 6 March 2014 1:04 pm , Vol. 343 , #6175
- About Us
ScienceShot: Ancient Fish Sported Circular-Saw Jaw
26 February 2013 7:01 pm
An ancient fish that sported a saw blade-like whorl of serrated teeth—and was long presumed to be a member of the shark family—actually belonged to a different but closely related group, a new study suggests. Members of the genus Helicoprion were first described in 1899, but fossils have been notoriously incomplete, with most including only spiral groupings of teeth. Although some fossils have also preserved hints of cartilaginous tissue, none have included the braincase or postcranial parts of these fish. Accordingly, scientists never came up with a convincing idea of what these creatures looked like, with some teams suggesting the whorls sprouted from the nose like an elephant's trunk, and others placing toothy appendages on the creature's tail, dorsal fins, or drooping from the lower jaw. Now, an x-ray CT scan of a particularly well-preserved fossil unearthed in Idaho in 1950—one that includes 117 teeth, the cartilage on which they were attached, and part of the upper jaw—reveals that the whorl resided within the animal's lower jaw (artist's concept above), researchers report online today in Biology Letters. The size and shape of the upper jaw fragment suggests that the creature was about 4 meters long, with some other species in the Helicoprion genus measuring almost twice that length. The arrangement of tissues in the animal's lower jaw, including those previously hidden by the rock that entombs them, definitively shows that Helicoprion is not a shark, the researchers say. Instead, the genus is nestled firmly within a group of cartilaginous fish known as chimaera, a lineage that includes species commonly known as ghost sharks and ratfish.
See more ScienceShots