To determine which numbered fossil was found in the lowest layer of sediment, we would typically consider that in geological studies, the oldest layers are found at the bottom, with newer layers stacking on top. However, since there is no specific chronological data or layering details provided in your question, I cannot identify which numbered fossil is in the lowest layer of sediment.
If you have additional information or context regarding the chronological data of the fossil layers, please provide that, and then I can help identify which numbered fossil is the oldest. Otherwise, based solely on the options given (A: 44, B: 77, C: 88, D: 1212), we cannot determine the correct answer without more details.