OSR: Fossil Dinosaurs

Filling out my Veinscrawl random encounter tables. Also, the Monster Manual has way too many dinosaurs in it and nobody seems to know what to do with them.

Dinosaurs were an accident. Rather, their extinction was an accident. Just after inventing the moon (to create tides and stabilize Creation's orbit), a passing bit of rock smashed into Creation and reset a few hundred million years of work.

Things eventually stabilized, but the age of the giant lizard-thing was over. Millions of them had been buried in sediment. They found a new life in stone, freed from biology, but not freed from hunger.

Their world is two-dimensional. They exist on the boundary between stone and air, half-buried, sliced, compressed. One leg in the rock, one out, one empty socket seeing air, one seeing stone. They move like creatures under a microscope slide. They can turn around and even dive into the stone, but they cannot break free and walk in the open air.

Blessedly, they are mostly harmless. The larger plant-eating creatures will protect their stone eggs and attempt to graze on fossilized plants. Lumbering, like inverted sailing ships, they slide along a cave wall in vast herds. A hallucination come to life; the real danger is shock and fear. Running away in the Veins is not always safe.

There are a few predators. They can't eat but they can hunt. Hard-scrabble claws attack fossilized ribs. Teeth clench around a fleshless neck. A shadow-box fight on a cave wall. A herd stampedes, shaking dust and gravel, and vanishes down a chasm. If you run, or if you move in just the wrong way, a toothy predator might think you are prey instead. A nightmare skeleton head darts out of the wall and bites off a limb then retreats, leaving a blood-stained patch.

And that's just the small predators. There are huge, impossible skeletons in the Veins. Long-necked paddle-finned things with mouths like beartraps. Bulky, stomping things with giant fist-shaped skulls and teeth like swords. A menagerie of horror; a Necromancer's nightmare.

Veins explorers call them, "Rock Beasts" or "False Basilisks" or "Bone Devils". Some people think they are demons. Some trap them and use them as guards or decorations. If you can lure one onto a stone block and separate the block from other stones - by water, by air, or by iron - the rock beast is trapped, unable to jump the gap.

There are fish as well, and strange snail-things, but they are too quick to catch.


The old Monster Manuals are full of dinosaurs. Use those. Divide all stats by 2 except AC and HP. Fossil dinosaurs take no damage from piercing weapons, 1 damage from slashing weapons, and full damage from bludgeoning weapons, etc. Fire can harm them but they do not burn.

Small dinosaurs can reach 3' out of the rock. Large dinosaurs can reach 5'. This includes the floor. In some caves, hanging from the ceiling via ropes or walking on stilts are the only safe options.

AD&D MM Name Page # 1d20 Veins Name Hostile?
Allosaurus 24 1 Greater Bone Devil Very
Gorgosaurus 25
Megalosaurus 26
Teratosaurus 27
Tyrannosaurus 28
Ceratosaurus 24 2 Lesser Bone Devil Very
Elasmosaurus 25 3 Snake Turtle Very
Plesiosaurus 27
Mosasaurus 26 4 Fish Devil Very
Pteranodon 27 5 Stone Bat Very
Dinichthys 25 6 Stone Fish Moderately
Iguanodon 25 7 Fat Beast No
Plateosaurus 27 8 Sprinting Beast No
Stegosaurus 27 9 Back Plate Beast Surly
Ankylosaurus 23 10 Turtle Beast Surly
Paleoscincus 26
Archelon lschyras 24 11 Giant Turtle No
Brontosaurus 24 12-15 Giant Beast No
Brachiosaurus 24
Camarasaurus 24
Cetiosaurus 25
Diplodocus 25
Anatosaurus 23 16-17 Duck Beast No
Lambeosaurus  26
Monoclonius 26 18-20 Plate Beast No
Pentaceratops 26
Styracosaurus 27
Triceratops 28

Greater Bone Devils
Big, fast, and mean. Blind predator faces. Unmistakable teeth. Biting, crushing, rearing out of the ground to snip off a leg.

Lesser Bone Devils

Small, quick, sharp. Claws and whip-tails and pack tactics.
Snake Turtles
Flippers on a turtle body with a huge snake neck and head. Bear-trap jaws full of needle teeth. The most feared, because they can flick their necks further out of the stone.
Fish Devil
Horrible staring eyes. Seems to be entirely mouth and teeth.

Stone Bat

Long spiked arms, folded and hidden in the roof. They dive down a cave wall like a shadow passing before the beam of a lantern, then rise from the floor to puncture and maim.
Stone Fish
Lumpy, plated, toothed. Might bite off a toe or a finger, or try to nibble on a rope or pack strap.

Fat Beast

Slow, dawdling. Rare, but it is considered good luck to see one in the Veins.

Sprinting Beast

Not predatory, but quick and nervous. Forms herds.

Back Plate Beast
Like the fat beast, but with huge sail-like plates and a spiked tail. Protective of fossil eggs.
Siege Beast
Like a stack of armoured chestplates. Slow, plodding. Club or spiked tails. Very useful for riding or climbing.

Giant Turtles

A proper giant turtle with a giant turtle shell. Harmless, elegant, casually flying through the rock.

Giant Beasts 
Impossibly large. Long necks and long tails. Huge limbs. Slow, peaceful.

Duck Beasts 
Flat shovel faces. They dig through stone. Sometimes, they spit out treasures or gems. Miners consider them a boon, though their herds are often stalked by Greater Bone Devils.

Plate Beasts 

Armoured heads with neck frills and spikes, like they are wearing elaborate collars.


Fossil Dinosaur Plot Seeds

1. A Speleonecromancer is trying to raise an army of rock beasts. Magic can pull the creatures from the rock and let them walk around in the open air, but the necromancer can't seem to control them once they are raised. She is currently hanging from the cave ceiling on a rope harness.

2. A mad Volume-Lord created a menagerie of trapped rock lizards. The menagerie is completely safe (he spared no expense) as long as the river water suspending the rocks continues to flow. If the river is blocked or diverted, the stones will slowly fall and unleash their half-embedded monsters into the community.

3. There are rumours of horrible bat-like bone devils in a deep cave. They flicker in and out of the rock, spearing people with their horrible serrated beaks. A deranged old cave-prophet lives among them. Anyone wishing to visit the prophet must avoid or distract his unnatural guardians.

4. A trilobite-knight rides the side of a rock-lizard like a vagrant hanging off a streetcar, lance raised, eyes keen. It will challenge any PCs to a good-natured joust. PCs are welcome to use a second dinosaur mount (on the other wall of a narrow canyon) or find their own (a sonic pig, another PC).

5. Someone stole and enchanted a tooth from a huge and monstrously hungry rock lizard. The creature can sense the tooth and hunts the bearer. However, the tooth also functions as a +3 dagger against creatures with flesh (or has some other equally tempting enchantment). The PCs find it on a mangled corpse.

6. The only way across a vast chasm is to catch a ride on the ribcages and spines of migrating rock beasts. Handholds change every few minutes, but if you are quick or daring it's far easier than climbing normally.

1 comment:

  1. I'm not sure how how these work. There cool: but rules as stated they cant leave the rock, there 2d. So how can they threaten a PC? I will say they are insanely cool!