The fossil remains of a foot-length, slimy sea dweller of 100 m years ago indicate that the last common ancestor of all vertebrates looked less like a soggy eel and more "fishy", researchers claim.
The fossil dug out of Lebanon eight years ago is an early hail fish, a peculiar creature with no jaws, eyes or true vertebrae, but who, in danger, can spit out a mixture that is in one Melting Slime
Anglerfish are typically found on the bottom of the sea where they dig and feed on dead sea creatures. Given the lack of bone, the scientists say that the discovery of an ancient hail fish was a surprise.
"It's as rare as finding a fossilized sneeze," said Professor Phillip Manning, co-author of the study and Natural History Department at the University of Manchester.
Writing in the Proceedings of the National Academy of Sciences The team says the analysis of the fossil, including a mapping of chemical elements, reveals a number of traits that are seen in hagfish today – including mucous glands.
The fossilized creature is not only amazing, even if it bears the name Tethymyxin tapirostrum or "slimy fish from Lake Tethys with a long, tapering muzzle" – could be a brawl among experts over the site where hail fish sit on the evolutionary tree of vertebrates.
Some believe the shape of hail fish suggests that similar creatures are close to the base of this tree, with jawless creatures, such as new muzzles, armored fish, and other vertebrates that evolve over time. But there is a problem: the analysis of DNA from hail fish and lamprey is at odds with this image, suggesting that these species originated from an ancient creature that had diverged early.
"For many years, the data came from you The DNA did not match what we saw in the fossil record," Manning told The Guardian. Without fresh fossils, the debate continued. But now, Manning says, the puzzle seems to have been solved.
"There are quite funky [characteristics] that exist relatively early in this animal," he said, adding that such traits – including mucus glands and unusual feeding mechanisms – suggested that a hagfish-type creature was not the last common ancestor of all vertebrates.
Manning said that the branching that caused hail fish and lamprey probably took place about 500 meters ago. But as the common ancestor of these creatures and all other vertebrates looked, it is still a mystery, though the team says it was probably more "fishy".
"This ancestor, X, which exists somewhere, leads directly to the monkfish and old fish, but also to a number of other jawless fish and the true fish and vertebrates like us," said Manning.
The hunt for this creature continues. "These ancestors will lurk either in a museum drawer or in the ground," Manning said. "That's fun. That means that paleontologists are still busy. "