"The blues had a baby and they called it rock 'n' roll," said the great Muddy Waters. But what was the firstborn? What was the first rock 'n' roll record? Using this question as their starting point, writers Jim Dawson and Steve Propes nominate 50 recordings for that honor. Beginning with a 1944 Jazz at the Philharmonic recording, "Blues, Part 2," and ending with Elvis Presley's "Heartbreak Hotel," What...