Answer
Dear Tom
This will be based on a misunderstanding. Sometimes some bones remain from a dead dinosaur, sometimes even an almost complete skeleton, but very rarely organic remains of the skin, muscles, entrails, or feathers(!). Their droppings are also found, but are then completely mineralized (‘petrified’) and contain virtually no organic material.
Formation of fossil fuels: Petroleum is formed from the organic remains of mainly plankton and bacteria that lived in the sea, while coal is formed almost exclusively from plant remains in wetland areas on land, such as swamps. Undoubtedly, many dinosaurs also died in a swamp, but the contribution of their organic remains to the later fossil fuel of that swamp (that is, coal) can be regarded as negligible.
During the coal formation of the Carboniferous Period (around 325 million years ago) in our region, the dinosaurs did not even exist. They only developed during the Triassic Period (around 240 million years ago).

Answered by
Prof. dr. Robert Speijer
Geology – Paleontology – Paleoclimatology. You study geology in Leuven!

Old Market 13 3000 Leuven
https://www.kuleuven.be/
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