Will mark

bird bones are not often found because:

birds did not exist until very recently
most bird species are now extinct
the bones are light and do not preserve well
scientists are not looking in the right places

the bones are light and do not preserve well

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.

answer; cattle ranching on the savanna,and forestry in the amazon;