Bonechewer1
Its dull scales the color of old, dead bone, this dragonlike creature creeps over the stones of the cavern, its batlike ears twitching; its eyes are dark, empty pits.

Bonechewer (CR 7; XP 3,200)
N Large dragon
Init +1; Senses blindsight 120 ft., scent; Perception +21
Defense
AC 21, touch 10, flat-footed 21
(+1 Dex, +11 natural, -1 size)
hp 95 (10d12+30)
Fort +10, Ref +8, Will +9
Immune sleep, sight-based attacks, paralysis
Offense
Speed 30 ft., fly 60 ft. (average)
Melee bite +14 (2d6+7), 2 claws +14 (1d8+5), tail slap +12 (1d6+7 plus trip)
Space 10 ft; Reach 10 ft. (15 ft. with bite)
Special Attacks breath weapon (80 ft. line; R-DC 20, see bonespew), tail snatch
Statistics
Str 21, Dex 12, Con 16, Int 8, Wis 14, Cha 10
Base Atk +10; CMB +16 (+20 grapple, trip); CMD 27 (31 vs. trip)
Feats Ability Focus (breath weapon), Flyby Attack, Multiattack, Skill Focus (Perception), Wingover
Skills Climb +18, Fly +12, Knowledge (dungeoneering) +12, Perception +21, Survival +15
Languages Draconic
Ecology
Environment underground
Organization solitary, pair, colony (5-10, plus 1d4 hatchlings)
Treasure double
Special Abilities
Bonespew (Ex) Bonechewers spit out a paste of stomach excretions and ground bone. Any creatures struck by this breath weapon who fail their Reflex save are immobilized. As a full-round action, those trapped may attempt to break free with a Strength or Escape Artist check against DC 20. The hardened paste has a hardness of 7 and 15 hit points. The save DC is Constitution-based.
Tail Snatch (Ex) Instead of tripping an opponent with its tail, a flying bonechewer that hits a creature no larger than Medium size with its tail can attempt to grapple the creature with its tail. On subsequent rounds, it can attack held creature with its tail, a claw, or fling it up to 50 ft. which will deal the greater of (5d6) or falling damage.

Some scholars think that bonechewers, as they are called for their favorite form of sustenance, are an engineered species, as some bold races of the dark spaces under the surface use them as mounts. They are no reports of bonechewers venturing to the surface, though there have been a few cases of them breaking into a burial catacombs and eating the entire contents of an ossuary.

They are persistent trackers with twice the blindsense of true dragons and keen senses. These eyeless draconians hug the ground when they move, batlike ears twitching constantly, and they fly erratically, more like a bat than a megalizard. More social than surface dragons, bonechewers enjoy the company of their own kind, and a colony will claim a large, open cavern as theirs, repelling all others; hatchlings are Small versions of adults, applying the appropriate template.

ON PORPHYRA
Bonechewers have been noted in the Underdeep, naturally, and if lacking their favored large caverns, claim large territories underground in their search for food. There has been efforts to breed them in the Empire of the Dead, hampered by the fact that they like to eat some of the more skeletal inhabitants of that domain.