a) Justin Murray supplied a creature that looked as if it were something that could have belonged to a dark fantasy barbarian stories which would have fit in with the intended tone of Paul Anderson's Aliens vs Predator which took inspiration from the Frank Frazetta paintings associated with the old Conan the Barbarian and other Edgar Rice Burroughs or barbarian paperbacks through the 1960s and 70s.
Predalien by Justin Murray
b) His Predalien looked as if it could be a hulking ferocious thing with extended mandibles and trailing dreadlocks that had become like tentacles. The pencil sketch on the right shows the creature with a row of skulls fixed to the side of its head. The concept of very elongated mandibles also can be found on a Predator mask design that he drew for the film project as well. See the Justin Murray's blog and www.justinmurrayart.com