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Ultrasound scans use high-frequency sound waves to produce pictures of your baby inside the womb.
This is done by building up pictures from the return of sound waves as they bounce back from resistance they meet within your body.
Since dromaeosaurs had only been found in places that used to be part of Laurasia, scientists figured that the beasts evolved into being after Pangea split.
But the Buitreraptor fossil in South America, which dates back 90 million years and closely resembles fossils from the North, means one of two things: Either dromaeosaurs existed when Pangea was intact; or the newfound Buitreraptor and its northern look-alikes evolved separately yet with remarkably similar results.
Evidence that they existed in the Southern Hemisphere has been mounting.
Today's announcement of a well-preserved fossil represents the first definitive evidence that dromaeosaurs roamed South America as well.
The other chunk Gondwana, developed into the continents of the Southern Hemisphere and India.
The new find suggests such raptors go back much further in time than previously thought.
Until recently, dromaeosaurs had been found only in Asia and North America and only in the Cretaceous period, which ran from 145 million to 65 million years ago.
The discovery changes the understanding of when humans reached North America.
The study, to be published this week in the science journal Nature, said the numerous limb bones fragments of a young male mastodon found at the site show spiral fractures, indicating they were broken while fresh.