Me: "These tables are awesome. You can roll on them and get a colossal flying reptile with tail spikes and a neck shield."
Roll 1d4, 1d6, 1d8, 1d10, and 1d12 all at once. Or, if you already know you need (for example) a huge bipedal ambush predator, just roll the d10 and d12.
Rolling the d10 and d12 multiple times is likely to produce absurd results that may or may not be just what you want.
d4
1 quadruped
2 flying reptile
3 biped
4 aquatic
d6
1 tiny
2 small
3 medium
4 large
5 huge
6 colossal
d8
1 pack hunter
2 ambush predator
3 solo hunter
4 territorial herbivore
5 curious herbivore
6 herd herbivore
7 curious scavenger
8 skittish omnivore
d10
1 neck shield
2 back shell
3 bright feathers
4 spiked joints
5 back fin
6 spine plates
7 bony skull ornament
8 neck frill
9 spine spikes
10 covered in bristles
d12
1 1d3 horns
2 tail club
3 tail spikes
4 long neck & tail
5 sharp beak
6 tusks*
7 razor claws*
8 disease carrier
9 acid spit
10 radioactive breath
11 froglike tongue
12 speech & intelligence
*All dinosaurs have bite and claw attacks. These ones just do a shitload of damage in comparison.
If you only roll the d12 one time, there's a 1/3 chance of getting an extremely not realistic result that changes up the encounter. That feels about right to me. If you want to cut that stuff out completely for some reason, just use another d8 instead of a d12.
Now have a drink and make up a kickass sword & sorcery style name for your dinosaur species, like "dragonhawk" or "great tooth" or even "death lizard." Repeat the process a few times, maybe fudge a roll here and there, and a whole ecosystem starts to emerge.
