"S" is for "Spidosaur"

Spidosaur

No. Enc.:  1 (1d4)
Alignment:  Neutral
Movement:  135' (55') 
         Swim:  45' (15')
Armor Class:  3
Hit Dice:  11
Attacks:  1 (bite, or tail-slap)
Damage:  2d12 + poison, or 2d8
Save:  L6
Morale:  11
Hoard Class:  VI
XP:  4,400

Spidosaurs, unholy arachnid/crocodilian hybrids, are 20'-25' long abominations found in fetid swamps, ruined sewers, and the rusting hulls of Ancient ships.  Though frequently encountered near watery environs, spidosaurs are ungainly swimmers, so they usually race along vertical surfaces and ceilings, or drop from treetops.

Spidosaurs sport toothy maws and enormous fangs that drip with a viscous Class 16 poison.  Their multiple eyes grant 360-degree vision, meaning the beasts are never Surprised.  A spidosaur's bellow echos for miles, and can paralyze prey by prompting primordial panic. 

Some of the most arrogant and militant races (like Clamazons, Karkhans, chaotically-inclined Manataur, and Goliaths [p. 74 of the Mutant Future Core Rules]) boast about taming spidosaurs as mounts, but those claims remain unverified.

Mutations:  Extra Parts (Eyes, Limbs), Shriek (Greater), Toxic Weapon (Venom)