CogSim, as I recall the description by the coroner in the New York Times article, the fractures were consistent with an individual's upper torso bending forward to something similar to the brace position, and then being flung backward with arms upraised.
Indeed. Thanks for the correction.
From The Times' article:
He leaned forward in his seat and wrapped his arms around his knees. “They were like this,” he said, holding the crash position and looking into my eyes. Then he sat up quickly and held his hand flat above the table. “When they hit,” he said, slamming it down, “fractures.
It is phrased weirdly. I took the "they were like this" to mean the bodies. Obviously, he is reconstructing the position at impact from the injuries.