Fish became land walkers 20 mln yrs earlier than previously thought

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Washington, January 7 (ANI): In a new research, scientists have discovered footprints from an 8-foot-long prehistoric creature, which suggests that ancient fish emerged from the sea to become land walkers almost 20 million years earlier than previously thought.

Dozens of the 395-million-year-old fossil footprints were recently discovered on a former marine tidal flat or lagoon in southeastern Poland.

The prints were made by tetrapods-animals with backbones and four limbs-and could rewrite the history of when, where, and why fish evolved limbs and first walked onto land, according to the study.

Because they are thought to have evolved from such creatures, reptiles, birds, and mammals-including humans-are today classified as tetrapods.

"These are the oldest tetrapod tracks and also the oldest evidence of true tetrapods," study co-author Grzegorz Nied Wiedzki, a paleontologist at Warsaw University, told National Geographic News.

The tracks were made by several individuals of a four-limbed species that had digits, or toes, on each foot, according to the research.

"We are dealing with creatures that were walking," said Marek Narkiewicz, a geologist at the Polish Geological Institut and co-author of the study.

The footprints vary in size, some as wide as 10 inches (26 centimeters).

The track sizes and shapes indicate flat-bodied, lizard-like creatures up to 8.2 feet (2.5 meters) long with stout legs, according to the researchers.

Discovered in an abandoned mountain quarry, the tracks suggest that tetrapods were traipsing the planet 18 million years earlier than previously indicated by the fossil record.

The tracks are also ten million years older than the oldest known fossils of lobe-finned fishes called elpistostegids, which are widely considered to be transitional forms between fish and tetrapods.

The age of the newfound tracks suggest that "these transitional fish continued to exist alongside the tetrapods for quite some period of time," said Per Ahlberg, a paleontologist at Uppsala University in Sweden, who led the new research.

The new tetrapod finding "could lead to significant shifts in our knowledge of the timing and ecological setting of early tetrapod evolution," said paleontologist Ted Daeschler. (ANI)

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