Ecology and evolution: Ecology and evolution: Animal people: News:

The first vertebrate fish appeared on Earth in the middle of the Paleozoic, 480 million years ago. The fossil record at this time is very rare. However, after 60 million years, various fish fossils are produced in abundance around the world. Where was the first fish?
The origin of fish is a hot topic of paleontology. The badertion that a variety of fish emerged around the early coral reefs was strong, since coral reefs are now the most abundant fish species. Indeed, the origin of invertebrate animals living at the bottom of the sea has been revealed around coral reefs.
However, the results of the study using "Big Data" came to an unexpected conclusion. The cradle that gave birth to vertebrates is a shallow sea near the shore, not a distant sea. American and British researchers, including Professor Lauren Sallon of the Pennsylvania University of Paleontology and the University of Pennsylvania, have identified 2728 species of chinless fish, fish fossils in the jaw and minced fish found in the world between 480 and 363 million years ago and the surrounding rocks were transformed into Big Data and published in the scientific journal "Science" on the 26th.

The paleontologist at the University of Birmingham, England, said Ivan Santham, one of the authors of the correspondence. "What surprised me was that all these fish started their evolutionary journey and that they were very shallow near the coast", Says in this college press release.
Researchers believe that the first shallow water fish from the intercontinental coastal lagoon and lagoon have remained there for more than 100 million years and have differentiated into different forms. The evolution of the body shape more flexible and thinner, the farthest from shallow waters close and competitive, advanced into the deep waters. Species whose shape resists environmental changes have migrated to freshwater or some have landed and turned into four-legged animals.
If the fish comes from shallow waters, why do the first fish fossils explain this rare event? "It's hard to leave a fossil because dead fish are carved quickly because they always hit the waves in shallow waters," said Professor Sallan. Says in this college press release.

Rocks with fossils indicate the environment at this time. You can also see if there is a coral reef, a shallow sea, a deep sea, a river or a river. ;a lake. However, the first fish fossil showed that it had deposited in a shallow marine environment.
So why could the shallow sea be the cradle of vertebrate diversity in the first place? "We still do not know what's special about the early shallow marine environment that allows the first fish to take the first steps in their evolution," said San Sam. "I think water chemistry and oxygen levels in the dynamic environment of shallow seas have something special, "he told The New York Times.

In any case, the coast has been a "hotspot" for biodiversity, and this function can still be alive. If coral, the cradle of biodiversity, is in danger of deteriorating in the long term due to climate change, the coast will be able to play its role and the conservation of the coast becomes more important. "Nowadays, climate change, sea level rise, overfishing and water pollution can be a fatal blow to the future diversity of species," San Sam said.
■ Articles quoted at the origin:
Lauren Sallan et al, The Coastal Cradle of the Early Diversification of Vertebrates, Science, http://science.sciencemag.org/cgi/doi/10.1126/science.aau8461
Cho Hong-seop reporter [email protected]