Fossils should spawn frequently and at shallow depths or surface in mesas.

Mesas and badlands are generally some of the most fossil-saturated areas in the real world, with areas such as Badlands National Park in the US having incredibly rich fossil mammal deposits. This makes sense seeing that they're predominantly made of sedimentary rock formations.

What doesn't make as much sense is why this isn't reflected in the world of Minecraft. Not only would fossils being abundant and relatively easy to find in mesa biomes reflect many of the badlands in the real world, it would give mesas a new and unique character and draw to make them more attractive to a wider selection of players, both for the utility of the bone blocks themselves, as well as the potential scenery with fossil structures being partially exposed to the elements as a result of prior weathering of the mesas. To this end, I propose that the spawn rate of fossils in mesas be double that of deserts/swamps or more, and that there should be a significant chance that fossils can spawn partially exposed to the surface in the cliff faces of mesas.