Ornithopter of Paradise got you
The print should not rub off or fade through normal use
Undying, on the other hand, sees that the creature has a +1/+1 counter and doesnt trigger since the creature doesnt meet its restrictions
Because casting a Lizard pings your opponent before it enters the battlefield, this makes all your Lizards enter with a counter, which is pretty strong, and putting counters on non-lizards isn't a massive challenge either
Early on I was playing Thought Scour but I havent really had any trouble fuelling my Uros or finding spells to return with my Mystic Sanctuaries, and having to mill my opponent when I wanted to draw a card Id just Sanctuaried to the top occasionally felt awkward, so I moved to trying out Hieroglyphic Illumination instead and have been happy
Your opponents can get put in a tricky situation if they have to split reanimation spells and reanimation targets, and you often benefit either way