Dinosaurs were once the most dominant species on Earth. However, a recent study has claimed that the creatures' mass extinction led to the emergence of ray-finned fish as the dominant species on Earth 66 million years ago.

A team of paleontologists from the University of California, San Diego, have marked the extinction of dinosaurs as the “ecological turning point” for the pelagic marine vertebrate, the Digital Journal reports. Ray-finned fish include a wide variety of the fish population, including tuna and nearly any tropical fish species found in an aquarium.

In the study, researchers examined the fossilized teeth of the ray-finned fish. The detailed examinations helped them establish that ray-finned fish did not emerge after the extinction of the dinosaurs. However, they just lived in an ecologically insignificant state.

The population explosion and dominance came after the extinction of the dinosaurs, when the ray-finned species got freedom from competition. “Mammals evolved 250 million years ago, but did not become really important until after the mass extinction. Ray-finned fish have the same kind of story,” said researcher Elizabeth Sibert of the Scripps Institution of Oceanography.

Ray-finned fish are known to possess bony fins. These comprise one of the most diverse fish populations, with nearly 99 percent of modern-day fish falling into that category. Nearly 30,000 ray-finned fish species exist in the oceans.

The complete study findings have been published in the journal Proceedings of the National Academy of Sciences.