海角大神

The soft-bodied fossil of the Tully Monster has been the subject of scientific debate for over 50 years. But a team of researchers from Yale, the American Museum of Natural History and the Argonne National Laboratory suggest in their that the squishy prehistoric fish was actually a vertebrate.聽

Amateur fossil hunter Francis Tully discovered the first Tully fossil in northeastern Illinois in 1958, and thousands of other Tully Monster fossils continue to be found at the site.聽And local interest in the Tully Monster mystery is enthusiastic, to say the least. It became the state fossil in 1989 and its image is even printed on some U-Haul trucks.聽

But despite the numerous fossils and its celebrity status, little is known about the physical characteristics of the 300-million-year-old, foot-long animal.聽

鈥淚 was first intrigued by ,鈥� says lead author Victoria McCoy in a press release. 鈥淲ith all of the exceptional fossils, we had a very clear picture of what it looked like, but no clear picture of what it was.鈥澛�

But now researchers say they finally understand the creature鈥檚 physiology.

The Tully Monster was a jawless fish, a vertebrate ancestor of the modern lamprey. It is described as 鈥渁n oddly configured sea creature with teeth at the end of a narrow, trunk-like extension of its head and eyes that perch on either side of a long, rigid bar ...鈥� Comparing the Tully Monster to a hammerhead shark, Ms. McCoy says their wide-set eyes gave them perceptual vision to see what their extended mouths were actually catching.聽

The authors refute previous assumptions about the Tully Monster that claim the animal was a mollusk, or made completely out of soft tissues.

鈥淏asically, nobody knew what it was,鈥� Derek Briggs, a geology and geophysics professor at Yale and聽co-author of the study, said in the release. 鈥淭he fossils are not easy to interpret, and they vary quite a bit. Some people thought it might be this bizarre, swimming mollusk. We decided to throw every possible analytical technique at it.鈥澛�

By using X-ray analysis at the Argonne National Laboratory, McCoy and her co-authors realized the 鈥榞uts鈥� of the Tullimonstrum gregarium were not all the same material, suggesting a notochord 鈥� aka a primitive backbone 鈥� existed.聽

鈥淭here was no big 鈥楢ha!鈥� moment that pointed to the lamprey. But put together, the strongest evidence was that it could be a lamprey,鈥� McCoy told The New York Times. 鈥淭he coolest thing is finding out that as weird as it looks, it is .鈥澛�

Connecting the Tully Monster to modern lampreys is especially interesting, Martin Smith from Durham University told The Atlantic, because even modern lampreys are considered one of the more archaic species.聽

鈥淟iving lampreys are often perceived as 鈥榩rimitive鈥� 鈥� a good proxy for ,鈥� said Dr. Smith. 鈥�Tullimonstrum provides a powerful antidote to this misconception: the lamprey lineage has undergone its own 500 million years of evolutionary experimentation, producing a great diversity of complex, unusual and sometimes unexpected body plans.鈥�