My frog died and mummified?

[Psychotic]

One of my recently acquired frogs just passed away. He had been sickly for a while. He stopped eating, became lethargic and died. I was going to give him a pedialyte soak today. However he did not make it through the night. Though I am saddened by this I'm also curious. When I went to sleep he was a fully fleshed frog, though on the skinny side from not eating. However when I woke up this morning at 6:00am and went to get him for his soak I found a mummified dried up husk in the shape of my frog. It looked like he had died years ago. How in the world did he decompose so fast!? The tank is not hot or dry. It's very humid in fact and rarely gets over 80 degrees fahrenheit during the day. I turn off light and heat during the night.

Is it normal he dried up so fast like that?

Thankfully the other frog hasn't shown any sign of illness. He still eats and is much bigger and robust than when he arrived. I know it's kind of a 50/50 when buying WC imported animals. So I think whatever killed this frog was something he came in with. Even when he first arrived he was on the skinny side and didn't seem as alert as the other frog. While he was eating he would only take one small cricket whereas the other frog would eat around three or four. Poor little guy will be missed.