In the 1994 German Tyco/Matchbox dealers catalog
Secret Skeleton Dinosaurs (repaints of the Dinosaurs)
were announced.
Although the marketing started over Europe and the single
packs had six languages on them
to my knowledge Secret Skeleton Dinosaurs were only released in the UK.
The Secret Skeleton Dinosaurs have a cold sensitive skeleton
painting. If they are dunked into cold water the skeleton
appears. Secret Skeleton Dinosaurs are made of harder rubber
than the earlier Dinosaurs.
The 24 different Secret Skeleton Dinosaurs were available in single
packs with a fact card. Also 4-packs and 12-packs were
announced but I have no pictures of these.
The fact cards had numbers from 169 to 192 but the figures
still had the numbers from the first series on them (145-168).
The molds were not changed.
Colors of the figures were yellow, green, orange, cyan, and
purple. The painting of the details of the figures is
different than the painting of the regular dinosaurs. This is
how they can be spotted easier than with looking for the
skeleton.
The catalog picture above shows prototypes of the Secret Skeleton
Dinosaurs with normally painted bones.
Pictures below have been taken after the figures had been put in
the fridge for 15 minutes.
The Secret Skeleton Dinosaurs belong to the most rare MIMP.
Figures:
Figure images by Wolfgang Schlögl.
A Secret Skeleton Dinosaurs single pack.
145. (169)
Tyrannosaurus Rex 
146. (170)
Apatosaurus 
147. (171)
Triceratops 
148. (172)
Stegosaurus 
149. (173)
Ceratosaurus 
150. (174)
Spinosaurus 
151. (175)
Iguanodon 
152. (176)
Plateosaurus 
153. (177)
Woolly Mammoth 
154. (178)
Cave Man 
155. (179)
Pteranodon 
156. (180)
Dimetrodon 
157. (181)
Sabre-Tooth Tiger 
158. (182)
Ankylosaurus 
159. (183)
Chasmosaurus 
160. (184)
Teratosaurus 
161. (185)
Styracosaurus 
162. (186)
Deinonychus 
163. (187)
Struthiomimus 
164. (188)
Kentrosaurus (Series 6 card) 
165. (189)
Monoclonius 
166. (190)
Parasaurolophus 
167. (191)
Lambeosaurus 
168. (192)
Baby Protoceratops 