Two rare, well-preserved fossil lampreys have been found in northern China. One of them, Yanliaomyzon occisor or “Yanliao sucker killer,” is 642 mm long and is the largest fossil lamprey ever found.
Their discovery sheds light on the feeding habits, life cycle and evolution of lampreys – an ancient lineage of jawless fish characterised by a funnel-like sucking mouth.
The specimens are detailed in a study published in Nature Communications.
Both fossils were found in the Yanliao Biota from rocks dating back 158–163 million years. The layers of volcanic tuff (a rock of volcanic origin, comprising compacted or cemented volcanic ash and dust) and sediment contain some of the world’s best-preserved fossils from the Jurassic period (201–145 million years ago).
Preserved in great detail on both fossils are the lampreys’ teeth, made of keratin. They bear a striking resemblance to the feeding apparatus of the living pouched lamprey, Geotria australis, found in the cool waters around southern Australia and New Zealand.
“Our study resolved these Jurassic lampreys as the closest fossil relatives to extant lampreys,” says lead author Wu Feixiang from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences.
“Contrary to conventional wisdom that modern lampreys’ ancestors fed on blood, our study showed that these two Jurassic lampreys must be flesh eaters, which foreshadows the flesh-eating habit of the most recent common ancestor of modern lampreys.”
The authors suggest that the Jurassic may have seen a fundamental change in lamprey feeding behaviour.
In an earlier period, lampreys were smaller and had weak, simply assembled teeth. Most other fish living at the time had hard exoskeletons. Pre-Jurassic lampreys were probably not predators.
“The abundant emergence of advanced teleost fishes with thinned scales by the Early Jurassic might have provided an important evolutionary opportunity for lampreys,” Wu explains.
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