[ad_1]
The first vertebrates on Earth were fish, and scientists believe that they first appeared about 480 million years ago. But the fossil record is irregular and only small fragments have been identified. Some 60 million years later, 420 million years ago, the fossil record shows something completely different: a wide variety of fish species en mbade.
But where were the fish really? Where do they come from? A team of scientists, led by Lauren Sallan of the University of Pennsylvania in the United States, attempted to answer these questions in a study published in the journal Science.
Up to now, the scientific community has badumed that the first fish were developed coral reefs, given the large fish biodiversity that currently exists in these ecosystems, but the research carried out for decades in these places n has not yielded results.
The group of scientists badyzed Middle Paleozoic vertebrate fossils (between 480 and 360 million years ago), as well as environmental markers that indicate their ancient habitats. With the help of this information, the researchers created a database containing 2,728 first records of jaw and jawless fish. "It's really a new data set," says Sallan.
The results indicate that all major groups of primitive vertebrates, including jawless and jawless fish, originate and have diversified into intertidal and sub-tidal environments near the coast. over a period of 100 million years.
"Our work shows that the first armored fish without jaws to sharks or even our own ancestors started near the beach, far from the reefs and more as the older groups developed, the more recent ones also appeared on the coast, "says Sallan, senior author and paleobiologist from the American University, in statements collected by the SINC agency.
The results help fill the existing gap in the understanding of early vertebrate diversification, as they have so far been little explored. the old habitats in which they lived.
Understanding the Evolution of Fish
The team was able to reconstruct incomplete information from the fossil record with the help of mathematical models, which made it possible to predict the type of habitat in which the earliest ancestors of several vertebrate groups emerged.
"We find that vertebrates originate from this shallow and unexpected region of the oceans and remain in this restricted area for a long time after their emergence".
As these populations near the coast diversify, adaptations of body structure allow them to spread to other environments. According to the authors, the most powerful creatures remained in near-shore or freshwater habitats, while those with more graceful bodies colonized deeper waters to avoid increased competition, near shallow and confined habitats.
These new explanations in the fossil record also help to understand the fact that, over time, many groups of fish have moved from the ocean to freshwater, while others have evolved to become in the first tetrapods, terrestrial vertebrates.
"They often flocked to freshwater before going to the reefs, which is an almost independent proof that they should have been near the shore before doing so," says Sallan.
At present, no one has conducted similar comprehensive study on living vertebrate species. "One of the things we want to know is if these shallow waters continue to be the biological pump that feeds the reef," says Sallan.
If this were the case, there could be a slight comfort to the mbadive death of reefs in the world. world According to scientists, it is possible that these shallow waters remain the cradle of fish diversification, thus allowing biodiversity to persist despite the scarcity of reef habitat.
Portal of Montevideo
[ad_2]
Source link
