Aerodactyl is not a D Tier Pokemon. I've had great success with it in the past, and I would be willing to contend it's B Tier at least, but for now, let's talk about moving it up to C Tier.
Aero does have its drawbacks, and I'm not ignoring those. Its defenses aren't great, its movepool is scarce, and its typing is somewhat unfortunate considering how prevalent bulky Water-types are in this metagame. However, it does have some very redeeming factors, one of which is its base 130 Speed. This Speed level makes it the fastest Stealth Rocks user in the entire game. Azelf, Terrakion, and Garchomp all pale in comparison. Another redeeming factor is its access to Taunt, making it a valuable option for neutralizing other common leads like Deoxys-D and Terrakion. Finally, it has access to the revered EdgeQuake combo, giving it coveted Rock/Ground coverage that hits just about everything for neutral damage, the exception being Bronzong. Not to mention, if you don't want to run Earthquake, you can surprise common Rapid Spinners like Forretress with other options like Fire Blast.
I used Aerodactyl as a lead for my hyper-offensive team in two World Cup of Pokemon games back in the summer, and I won both thanks to its speed and versatility, Fire Blast catching one of my opponents' Forretress off-guard for a OHKO that later won me the match. I continue to use Aero today, and it has never disappointed me. Petitioning for its elevation to C Tier, and we'll go from there.