This is interesting news (hat tip to Tim again) but caution is obliged because they are talking as of now of a mere visual survey by an archaeologist, Dr. Mason, who is not an expert in Neolithic (but was studying some Medieval frescoes instead).
All the information I have is in this article from The Independent.
The dates provided are just a mere hunch and even the role of the structures as tombs is as of yet mere speculation.
It is also rather shallow the comparison with Salisbury Plain, where Stonehenge is found.
Two types of structures seem to co-exist side by side: the corbeled structures and the stone rings.
The closest I can think to corbeled structures in West Europe are the tholoi or beehive tombs (a "Neo-Megalithic" tomb style found primarily in Southern Iberia since the the 3rd millennium BCE) and related. This architecture has precedents in Cyprus and Tell Halaf but then they were not used as tombs yet but as habitations or chapels. The first use of tholoi for burial is with all likelihood from South Iberia in the said 3rd millennium (early Chalcolithic by local chronology, Middle Chalcolithic by pan-European one). Architecturally related buildings are the nuraghe of Sardinia and the motillas of La Mancha, which are forts instead and belong to later periods (Bronze Age).
However corbeled arch buildings properly speaking do not appear in West Europe until the navetas of Majorca, which are from Iron Age (very late).
So in this sense the comparison with Western Megalithism is misleading. If it has no dolmens (trilithons) there is no Megalithism as in Western Europe, which is best defined as Dolmenic Megalithism and in which stone circles, alignments, cairns, tholoi, artificial caves, silo tombs, etc. are rather epi-phenomena and not the defining characteristic of Western Megalithism.
More intriguing (but still unrelated to Western Megalithism) are the stone circles. These are small ones, with a diamater of c. 2 m. and made up of small stones. Nothing to do with the great stone circles of Egypt, Morocco or Britain, which seem to have an astronomical purpose primarily.
However there are two phenomenons in Europe that did build similar stone circles on totally different time frames:
- The Boleráz group of the central Danubian Plain, c. 3500 BCE, built such stone rings (1-3 m. diameter) as cremation tombs. The ashes were accompanied with some grave goods: jar and cup, stone axes and shell beads. This group is sometimes considered important in kick-starting the Baden culture (the last important one of the Danubian Neolithic), but these, unlike the Boleráz group, followed traditional Balcano-Danubian burial customs (fetal position, no cremation and no stone ring).
- Pyrenean Iron Age also includes such stone rings (restricted to a mountain area) some 3000 years after Boleráz. The coincidences are size of the rings and cremation burial but there were normally no grave goods and the time-frame is so distant that it feels almost ridiculous to make a comparison.
The article also mentions (Prof. Banning) that other such sites are known to exist (from satellite imaging) in the Palestinian and Jordan deserts.
We will have to await further research.