March 10 (UPI) – There is little fossil evidence of the earliest vertebrates on Earth, but many scientists agree that a model for the ancestors of the vertebrates can still be found living in the coastal and freshwater waters of most areas. moderate.
Evolutionary biologists have long argued that the blind larvae, which feed on seeds, represent an evolutionary trap millions of years ago – anatomical anachronism.
However, new fossil evidence – described Wednesday in the journal Nature – threatens to weaken the long-accepted theory.
Scientists have discovered fossil fish larvae which note that old-fashioned lamprey hats looked much more like modern adult lampreys than their new larval counterparts. -nodha.
“Scientists of the nineteenth and early 20th centuries unreasonably saw lamprey larvae as a good model of common, and perhaps primary, conditions for all invertebrates,” said co. -author of the study Mike Coates to UPI in an email.
“The theory continued, mainly because it responds to a common notion of evolution from simple to complex, and that development from egg to adult could replicate the history of evolution, “said Coates, a biologist with the University of Chicago.
Despite the magnitude of the theory, scientists have never found direct evidence that a simple worm-like plan of modern-day lamprey larvae is traced to the beginning of vertebra evolution.
For the most recent study, scientists analyzed the remains of ancient lamprey larvae and hatchlings found in Illinois, Montana and South Africa.
By looking at dozens of ancient samples from several deposits from the Palaeozoic period, researchers were able to reconstruct the life cycle of lampreys – following their development from hatching to adulthood.
More importantly, the well-preserved juvenile specimens showed that old lampreys, at the stage of larvae and hatching, were in stark contrast to their modern-day contemporaries, juveniles that feeding on seeds called ammocoetes.
“The new fossil finds – fossils of larval and juvenile eels – reflect the features present in modern adults, including developed eyes, a gill basket to support it. the gills, and a toothless oral disc, are similar to the rasping courtship present in adult lampreys today, “Coates said.
Scientists first identified the blind larvae, which feed on seeds, as a model for early vertebra evolution because they had little fossil evidence to proceed. Over the last few decades, however, scientists have begun to discover remnants of early vertebrates.
The authors of the latest paper say it is time to take a closer look at that fossil evidence.
“The earliest spines may be better understood by paying more attention to the fossil evidence, and using this to elicit evidence from the development of lamprey,” Coates said.
Moving forward, Coates and his colleagues will continue to look for the remnants of primitive Palaeozoic vertebrates, as well as using the data they already have to action and ecology. identify early lamprey knowledge.