100 million years is a horribly long time ago.
I wonder whether there was sap (amber) that long ago.
Conifers
https://www.forestryengland.uk/conifers
The question has to be, what was the force which ‘squeezed’ the sap from the trees in liquid form which instantly entrapped living creatures...?
https://www.bing.com/th?id=OPA.j5brQv92rt0m5A474C474&w=256&h=256&o=5&pid=21.1