An idea of why the PredAlien has a Predator skull under her dome...

[War Wager]

Because she's the first of her kind.

An idea I had was that the first Aliens do be burst from a host have their hosts skulls under their domes. The same reason why Kane's Son has one too, because that is the first time a pure breed Alien is birthed from a human. Though the first ever human to be a host would have been thousends of years ago in the ancient times. That Alien would have had a skull, but since those Aliens DNA had been screwed around by the Predators, the first AvP Aliens are completely different to the beast in Alien.

Just a theory...

[Uncanny Antman]

There's no way she's the first PredAlien.

Do you really think that when the Predators first discovered the Alien, they never suffered a single loss that wasn't straight death?

There'd have been heaps of 'em over time, you'd think.

[Demonio Cazador]

I think it's more the Bros/ADI going back to the original Giger concept. Something Cameron/Winston decided to ignore due to production issues I believe. But the Bros/ADI also decided to use that design for the warriors/drones. So that definetely shows there's no intended explanation, just a creative decision.

[Xenomorphine]

Theoretically, they all could do.

Personally, I've never noticed the one in 'Alien', even though it's in the various production stills. I really never see it, when I watch the film.

[Porkus Maximus]

Pretty sure there's never a single moment in the film where the ALIEN skull is actually visable, except for maybe a quick freeze frame.

[darkfaerytales]

no, simply no

[Master]

Theoretically, they all could do.

Personally, I've never noticed the one in 'Alien', even though it's in the various production stills. I really never see it, when I watch the film.

I`ve also never seen skull under dome. But it would be very nice if in feature Alien/AvP films this would be a trait of all aliens without exeptions.

[shakermakerman]

Theoretically, they all could do.

Personally, I've never noticed the one in 'Alien', even though it's in the various production stills. I really never see it, when I watch the film.

I`ve also never seen skull under dome. But it would be very nice if in feature Alien/AvP films this would be a trait of all aliens without exeptions.

you can just see it in some scenes

[$cHm0cK]

I have a better idea ... the Predalien has a Predator Skull because ... its a Predalien.

....... 

greetz

[Dasani]

Or it looks really cool and it's a nice nod to the original.

[D88M]

Maybe because she chestbursted from a predator

[War Wager]

I know they only wanted a skull because it looks cool... 

I'm just thinking of a reason fan-wise.

[Foundationman2]

To tell you the truth, I'm kinda glad they didn't show the skull in Alien, because I wanted the alien to be very inhuman and the fact that it has a human skull under the dome, kind of turned me off. The alien dna can obviously replicate a human skull, and thats just a bit too much from the host.

[Sheriff Eddie Morales]

There's no way she's the first PredAlien.

Do you really think that when the Predators first discovered the Alien, they never suffered a single loss that wasn't straight death?

There'd have been heaps of 'em over time, you'd think.

She IS THE FIRST PREDALIEN.
Probably the Predators are not such bad monsters like us,people,and they will never sacrifice a Predator just to see what will a PredAlien will look like.People may do it if they discover an alien lifeform who reproduces like the Aliens.People will sacrafice one human to see what will this alien lifeform look like.
Funny,huh?

[agent_unawares]

There's no way she's the first PredAlien.

Do you really think that when the Predators first discovered the Alien, they never suffered a single loss that wasn't straight death?

There'd have been heaps of 'em over time, you'd think.

She IS THE FIRST PREDALIEN.
Probably the Predators are not such bad monsters like us,people,and they will never sacrifice a Predator just to see what will a PredAlien will look like.People may do it if they discover an alien lifeform who reproduces like the Aliens.People will sacrafice one human to see what will this alien lifeform look like.
Funny,huh?

You're saying that back when the Predators discovered the Aliens, you don't think they had any accidents? And you can't really say "They'd be smarter than the human scientists and not mess with them," since they obviously did mess around iwth them and are still carrying them around in their ships and breeding them to this day. XD