According to the KU researcher and fellow authors Meemann Chang, Feixiang Wu and Jiangyong Zhang of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing, the larval fossils show the life cycle of the lamprey “emerged essentially in its present mode no later than the Early Cretaceous.”
This cycle consists of a long-lasting larval stage, a metamorphosis and a comparatively brief adulthood with a markedly different anatomy, according to the PNAS paper. The larvae come from the fossil lamprey species Mesomyzon mangae.
“Our larvae look modern,” Miao said. “The developmental stage is almost identical to today’s lamprey. Before this, we didn’t know how long lampreys have developed via metamorphosis. Now, we know it goes back 125 million years at least. In other words, lampreys haven’t changed much—and that’s very interesting.”
Then, like today, lampreys lived in both freshwater and saltwater. At the larval stage, they’d have dwelled in the sand or mud and drawn nutrients from micro-organisms in the water. Then, as mature lampreys, some of them would have subsisted by fastening themselves to host organisms and swigging their blood—often killing their host in the end.
Indeed, they “would have.” Lampreys are, as it happens, a threat to the Great Lakes fishery, for all that they are supposed to be so primitive. Here are lampreys building a nest:
How does a life form get classed as “primitive”? Why? Keep asking. Never get a clear answer.
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