Semionotus sp. imprint

Semionotus sp. (possibly S. micropterus?)

Early Jurassic, Shuttle Meadow Formation.

Connecticut.

Poorly preserved imprint of skull, pectoral fins, and front half of the body.

I've noticed that the presence of the orange -powdery material can be an indicator of the presence of organic remains, and almost always is found when the fossil is badly articulated or poorly preserved, indicating (to me ) that the material is formed from something that was produced by the actions of decomposition.

I've not found any information in any of the scientific papers that I've read that explains/discusses the presence of this orange material.

I think I'll call it "Organic Rust".