Variants of a mold are catalogued separately, so each one has its own sets and minifigs. Check these too if something you expect is missing here.

• 40373 Animal / Creature Body Part, Dinosaur Body Quarter with Pin Holes this part is a pair of it
• 40374 Animal / Creature Body Part, Dinosaur Body Quarter with Pins [Plain] this part is a pair of it
• 40387 Animal Body Part, Dinosaur, Mosasaurus Head, Toothed with Pin this part is a pair of it
• 40387pr0001 Animal Body Part, Dinosaur, Mosasaurus Head, Toothed with Pin, Dark Gray, Red, and Dark Blue Print this part is a pair of it
• 40389pr0001 Animal Body Part, Dinosaur, Styracosaurus Head, Crested Neck and Nose Horn, with Pin this part is a pair of it
• 40390 Animal Body Part, Dinosaur, Tyrannosaurus Rex / Spinosaurus Lower Jaw, with Pin this part is a pair of it
• 40395 Animal / Creature Body Part, Tail / Neck, Base Section with Black Pin this part is a pair of it
• 40396 Animal / Creature Body Part, Neck / Tail, S Curve with Pin this part is a pair of it
• 43890c01 Animal Body Part, Elephant Head with Pin Pair of this part
• 47396 Creature Body Part, Dewback Head this part is a pair of it
• 51689 Creature Body Part, Varactyl Head, 'Boga' this part is a pair of it