The amount of Nitrogen built up in the joint, as well as the strength of muscles around the joint, and the cartilage that holds that joint in place
The best pyramid for this is the biomass pyramid. That is because they show how much ecological material can be found at each trophic level, which then can be used to model how the matter flows through the ecosystem that is being analyzed.
Fossils help scientists date rocks: True
Sometimes younger rock layers are found beneath older rock layers: True, because it happens with landslides and other causes.
No fossils from the Precambrian era have been found because there were no organisms at the time: False because there were organisims like algae and bacteria, and there are a very small amout of fossils from that era.
The map of Earth has changed over millions of years, but is now set: False