Complex sentence: The alligator snapping turtle ("Macrochelys temminckii") is the one of the heaviest freshwater turtles in the world, having been recently proven outweighed by the Hoan Kiem Turtle, a giant softshell turtle.
Split into simpler sentences: The alligator snapping turtle ("Macrochelys temminckii") is the one of the heaviest freshwater turtles in the world. Having been recently proven outweighed by the Hoan Kiem Turtle, a giant softshell turtle.