Lampreys are the vampires of the ocean and lakes that can attack. While these eel-like parasitic vertebrates do not use two sharp teeth to suck blood, lampreys have a serrated oral sucker that latches onto their prey and feeds on the blood of their host. Modern lampreys are found in the temperate zones of most of the world’s oceans, with the exception of Africa. However, specimens of their extinct ancient ancestors are quite rare in the fossil record, although they date back to about 360 million years ago. Now, paleontologists in northern China have discovered two unusually large fossil lamprey species that fill a major evolutionary gap. The specimens are described in a study published Oct. 31 in the journal Nature Communications.
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“We found the largest fossil lampreys ever found in the world,” said study co-author and Chinese Academy of Sciences paleontologist Feixiang Wu PopSci. “Based on these fossils, our study suggested that the most recent common ancestor of modern lampreys was probably a meat-eater rather than a blood-sucker as traditionally thought.”
The earliest known lampreys date back to about 360 million years ago during the Paleozoic Era. These early species are thought to have been only a few inches long and had weak feeding structures. The 160-million-year-old fossils in this new study were found in the Lagerstätte Yanliao Biota in northeastern China and date from the Jurassic period. The longer of the two specimens is named Yanliaomyzon occisor. It is more than 23 inches long and is believed to have had 16 teeth. The shorter 11-inch-long species is named Yanliaomyzon ingensdentes and had about 23 teeth. By comparison, modern lampreys range from six to 40 inches.
Their well-preserved oral discs and “biting” structures indicate that these lamprey species had already evolved improved feeding structures, larger body size, and were predators during the Jurassic period. It also appears that by this time they have already developed a three-phase life cycle
Lampreys begin life as burrowing freshwater larvae called ammocetes. During this stage, they have rudimentary eyes and feed on microorganisms with their toothless mouths. They spend several years in this stage before becoming adults. Some move to salt water while others will stay in fresh water. As adults, they become parasites that attach to fish with their mouths and feed on their blood and tissue. The lamprey eventually return to freshwater to breed, where they build a nest, then spawn and then die.
It is not yet clear when lampreys developed this life cycle and their more complex feeding teeth. These new well-preserved fossils fill an important gap in the fossil record and provide some insight into how its life cycle and diet originated.
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The study also pinpoints where and when today’s lamprey first appeared. “We place the origin of modern lampreys in the Southern Hemisphere in the Late Cretaceous,” says Wu.
The Late Cretaceous lasted from 100.5 million years ago to 66 million years ago and ended with the mass extinction that wiped out the dinosaurs. In future research, the team would like to look for specimens from the Cretaceous. According to Wu, this period of time could be very important for their evolutionary history.
More fossilized specimens could also give more accurate ideas about what types of flesh the ancient lampreys with all those teeth were feeding on and how that evolved over time.
“Living lampreys are always hailed as ‘water vampires,’ but their ancestor may have been carnivorous, their teeth suggest,” says Wu.