I assume those are the two dinosaur silhouettes based on context clues and my meager paleontological knowledge. Anyone made it to the dinosaurs yet? Are they as fun as they should be, are they sufficiently creepy looking and does the dilophosaur spit acid (it shouldn't, but pop culture overrides science in this game so far)?

They look like raptors from Jurassic Park more or less, so they're much taller and much shorter in length than they would be in reality. With both dino types you can't use any side routes (you can't even go behind railings next to buildings) of any kind and can't go in the sewers, the map seems "smaller" or at the very least simpler while playing them. No spitting just standard bite and tail swipe. Deinonychus plays basically like a cheetah (Fast, low hp), Dilophosaurus has the highest attack in the game, decent hp, and the lowest hunger in the game, while still retaining cheetah speed.

Deinonychus is a boss type to unlock, in my case there were a bunch of buffalo being chased by them so I just stealth killed the boss mid chase and died shortly thereafter. Dilophosaurus is a territory taking mission, first time I tried I died almost immediately, second time there were herbivores for them to chase (actually trying to fight more than one Dilo at a time, even with HP boosted to 3 times as much, is more or less suicide) and I captured territory while they ran around.

That fits... to be honest, deinonychus is the real world version of the Jurassic Park velociraptor. Real world velociraptors are (sorry, were) about the size of a largish chicken, no where near man sized. The name just doesn't roll off the tongue like "raptor." Sounds like a fun goal to aim towards, hope it doesn't take me forever. Any story given hints about why the hell there are dinosaurs? A lab experiment gone awry or something?

It's literally "Law of conservation of mass" and that's it to explain pretty much everything, not much of a spoiler. There's a lot more about something else that only appears as a rare event, and absolutely nothing addresses what happens after year 100 in survival, but I'd almost prefer if there was little or no explanation for anything in this game. Every unlock past Hyena can be quite difficult, I assume I was fairly fortunate beating every one on the first or second try, but it could take you four or five, especially Lions and Dilophosaurus.