The later structures are suggested to be funerary. The oldest one (with the lobes) is unknown. From the aerial photo, it seems they haven't dug the interior.

They mention a gravel layer in the ditch which suggests a palisade. I'm not quite sure how they get there (I don't see the actual report), but presumably they have some basis. As a fenced enclosure, it seems to small for livestock, but perhaps a fortified homestead.