Derpy from the side and infernal from below, the lamprey is the desert of the Great Lakes fishing industry. A jawless fish, sucking blood, the lamprey is often considered an early ancestral vertebrate for its rudimentary morphology and larval life stage. Now, a team of researchers has authorized a new study on fossilized lamprey larvae from the Devonian period that is said to have evolved differently than previously thought. This would mean that we should change our story about the origin of vertebrates.
The work of the researchers was published Wednesday in the journal Nature. Their argument depends on the life cycle of the lamp. Modern lamprey larvae, called ammocetes, are blind filters, which later turn into their adult, predatory self. Biologists and paleontologists have seen that both the stage of the amocoet larva is a relic of the early evolution of vertebrates and a sign that the lamprey could be invoked as a living fossil, which helps explain where all networked animals come from. But the recent team describes non-smoky lamprey fossils for children – these fossils look exactly like smaller versions of adult lampreys – suggesting that larval stage was a later evolutionary adaptation, a unique one for lampreys.
“Now it looks like the lamps are the weirdest,” said Tetsuto Miyashita, a paleontologist at the Natural Museum of Canada and lead author of the paper, in a video call. “[The lamprey] they look primitive, more primitive than these vanished fish without jaws. But it was the other way around. ”
Miyashita’s team describes four different species of old lampreys from Africa and North America, ranging from 360 to 310 million years old. At that time, the localities of Montana, Illinois and South Africa (where eel-like lamps were excavated) were shallow seas; a habitat different from the fresh waters in which the largest lamprey swirls today.
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The non-amocoet fossil amphibian was not a smaller group of adult lampreys, the team says, because some of the fossilized fish even have yolk sacs still attached to their bodies. If this were only in one place, “we would have thought that we are looking at this genealogy of the really strange, specialized, extinct lamprey, which has done its own thing and may have lost the larval stage of filtration. Miyashita said. “But species after species after species, in four different descendants of fossil lamps, they look the same.”
The authors propose that the stage of the amokete larva was an adaptation developed by the lamprey to move in freshwater environments where it now thrives too well. invasive lamprey population in the Great Lakes. First observed in Lake Ontario in 1835, lampreys spread to other large lakes in the mid-20th century. Now, the established population is wreaking havoc on trout, whitefish, cisco and other lake fish species, catching them with suckers, eventually killing them. Until the 1960s, the annual catch in the Great Lakes was 2% of its previous average; a dramatic nosedive attributed to the lampre.
“These species, such as the lamprey, which we consider ‘ancient fish’, have evolved as long and are not frozen over time,” said Jera.Miah Smith, a biologist at the University of Kentucky who was not affiliated with the recent newspaper, in an email. “More broadly, the study clearly shows that it is important to consider alternatives to widely accepted evolutionary scenarios and how new data sets continue to shape our understanding of the history of deep vertebrate evolution.”
For an alternative candidate for a vertebrate ancestor, researchers are proposing an armored Devonian fish called ostracoderm, which closely resembles warblers going to war.
“Lampreys aren’t exactly the swimming time capsules I once thought they were,” co-author Michael Coates, a biologist at the University of Chicago, told a Canadian Nature Museum. Press release. “They remain important and essential for understanding the deep history of vertebrate diversity, but we must also recognize that they have evolved and specialized in themselves.”
This story has been updated to include comments from Jeramiah Smith.