Visiting Professor in Biology Thomas M. Evans predicted early lampreys did not have a larval stage in a paper he coauthored in 2018 titled “The Evolution of Lamprey (Petromyzontida) Life History and the Origin of Metamorphosis,” which is now cited in a paper published in the prestigious journal Nature.
Lampreys are a primitive fish, that look like an eel but live a life without jaws. Lampreys swam the ocean hundreds of millions of years before the first dinosaur ever took a breath, so their development and body has been well studied to understand how vertebrates evolved. Lampreys have a complex life cycle that looks more like a butterfly than a fish because it includes a larval stage and metamorphosis. Until recently, the larval stage was assumed to be the best example of any early vertebrate, because it was far more like a worm than a fish, living in stream sediments and filter feeding. However, recent fossils have shown that early lampreys did not have a larval stage.
While this news is exciting, forcing us to reconfigure our understanding of vertebrate evolution, Evans’ work shows that while we can get our assumptions wrong, we can also detect when we have made incorrect assumptions and re-correct.