6-foot megalodon shark babies were cannibals in the womb, study says

Megalodons can live to be up to 100 years old and swam in the world's oceans millions of year ago.

(CNN)These extinct sharks gave birth to some really large babies -- about the size of a full-grown human adult.

At birth, megalodons were about 6.6 feet, or 2 meters, in length, according to a study published Sunday in the Historical Biology journal.
Megalodons, scientifically known as Otodus megalodon, were huge sharks that grew up to 50 feet in length and roamed the oceans 15 million to 3.6 million years ago, said study author Kenshu Shimada, professor of paleobiology at DePaul University in Chicago.
    The 6.6-foot measurement is fairly accurate and aligns with other findings at megalodon nurseries in Panama and Spain, said Jack Cooper, a fossil shark researcher and doctoral student at Swansea University's department of biosciences in Wales, United Kingdom, who was not involved in the study.
    The study is significant because there is not much research out there about the megalodon's reproduction, he said.
    Researchers counted the number of growth bands on the megalodon's vertebrae for the study.