At then end of Prometheus, the alien that Elizabeth Shaw extracted from her womb kills the Engineer then dies. Later on, a primary form of alien xenomorph is seen bursting out of the Engineer's chest. The scene takes place in Meredith Vickers' escape pod, stranded at a distance from the Engineers' crashed ship.
At the beginning of Alien, the team that explores the derelict ship discovers the body of an Engineer pilot:
The corpse wears what we now know is some sort of armor, and his chest has been damaged by an alien xenomorph, as we later figure out.
Everything seems to indicate that the corpse in Alien is actually the Engineer in Prometheus. However, there are two major discrepancies:
- The Engineer is killed in the escape pod, not in his pilot seat.
- The corpse in Alien is much taller that the Engineer in Prometheus.
What other theory could possibly explain how a (much taller) Engineer sat in the crashed ship and was killed by a xenomorph?