The Ecology of the Piercer in #72, according to my Dragon Archive CD's.
....and then I found an old thread on these boards that showed:
72 - Piercer
73 - Catoblepas
74 - Bulette
75 - Mimic
76 - Beholder
77 - Unicorn
78 - Mind Flayer
79 - Treant
80 - Doppleganger
81 - Basilisk
82 - Peryton
83 - Stirge
84 - Trapper
85 - Ixitxachitl
86 - Slithering Tracker
87 - Dryad
88 - Rust Monster
91 - Leucrotta
92 - Ettin
93 - Eye of the Deep
94 - Chimera/Gorgimera
95 - Cockatrice
96 - Gulguthra
97 - Gorgon/Gorgimera
99 - Will-o-wisp/Boggart
104 - Ochre Jelly
106 - Maedar/Medusa
107 - Sea Lion
109 - Displacer Beast
114 - Remorhaz
115 - Harpy
116 - Minotaur
117 - Anhkheg
119 - Korred
120 - Gas Spore
122 - Rot Grub
123 - Leech, Giant
124 - Gelatinous Cube
125 - Greenhag
126 - Shade
127 - Yeti
131 - Aboleth
131 - Hook Horror
132 - Aurumvorax
133 - Carnivorous Ape
134 - Red Dragon
135 - Cave Fisher
137 - Carnivorous Plants
139 - Spectator
146 - Dragons (2nd Ed.)
151 - Kappa
151 - Yuan-ti
152 - Umber Hulk
153 - Manticore
155 - Satyr
156 - Behir
157 - Wemic
160 - Gibbering Mouther
161 - Griffon
164 - Iron Cobra
167 - Su Monster
172 - Galeb Duhr
173 - Flind/Gnoll
187 - Dakon
190 - Actaeon
192 - Lamia
197 - Giant Scorpion
214 - Neogi
214 - Owlbear
215 - Amphisbaena
218 - Bird Maiden
219 - Black Pudding
221 - Crystal Spider
222 - Penanggalan
223 - Chitine
224 - Lammasu
227 - Osquip
232 - Roper
235 - Troglodyte
An1 - Wyvern
239 - Stirge
240 - Nymph
An2 - Shambling Mound
242 - Mongrelman
244 - Sphinx
245 - Steeder
246 - Flumph
251 - Wererat
252 - Ghoul
An3 - Steel Dragon
254 - Cyclopskin
257 - Firenewt/Giant Strider
258 - Flail Snail
260 - Aspis
261 - Dark Naga
262 - Jermlaine
An4 - Gray Ooze
266 - Xixchil
267 - Carrion Crawler
269 - Pseudodragon
270 - Gorbel
271 - Bag of Devouring
272 - Hydra
273 - Hippocampus
275 - Darkmantle
276 - Sheet Phantom
An5 - Feyr
282 - Purple Worm
300 - Mummy
301 - Troll
309 - Hobgoblin
312 - Drider
314 - Salamander
322 - Dark Ones
323 - Choker
324 - Night Hag
325 – Duergar
326 – Rakshasa
327 – Grimlock
328 – Will-o-Wisp
329 – Kenku
330 – Chuul
331 – Green Hag
332 – Kobold
333 – Behir
334 – Kraken
335 – Lizardfolk
336 – Spawn of Kyuss