I was wondering, could the use of chitin (assuming it's composed the same as in insect exoskeletons) combined with hydrocarbons feasibly make a working endoskeleton? I know that chitin could be used as a more flexible, power-hungry bone alternative, and in the world of Snaiad, the organisms had an endoskeleton using Hydrocarbons resembling extremely hard wood. I would like to know if a combination of the two could form a working endoskeleton? What I mean by this is, a skeleton made of Chitin reinforced by Hydrocarbons throughout in specific places.
Any relatively hard material could be used in a skeleton. There will be some advantages and disadvantages depending on what is used, but there is a reason why bone tends to be used for endoskeletons.
Both chitin and wood are more pliable and regenerate better than bone, which is good for an external covering since external coverings are more prone to getting worn away, scratched or damaged. Bone is not expected to be damaged in an animal's normal life, so more energy could be put into making it strong and supportive.
So a chitin/hydrocarbon blend could be used as a working skeleton. It probably wouldn't be quite as effective as a bone one, but evolution doesn't have to yield perfect results, just functional ones.