Dear Reb Dovid,

The term Aron does not necessarily mean coffin. In the language of the Talmud it sometimes refers to a tombstone. See, for example, the Gemara (Berachos 19b) that says that they would jump from one Aron to the next in an effort to see a royal procession. Perhaps that it is the understanding of the Gemara (Berachos 19a) that says that someones that dies in a state of Nidu'i has a stone placed on his Aron, that is, on his tombstone.

Furthermore, according to Rashi, what they do here in Eretz Yisrael - laying stones along both sides of the Meis and then resting flagstones on the top edge of these stones - would be called an Aron. Rashi says (see Shabbos 152b) that Gollel and Dofek, mentioned several times in the Gemara, refer to the top and side coverings of the Meis (it does not sound like Rashi is referring to the top and sides of a wooden box).

Furthermore, even when Aron refers to a wooden box, it could be that the box was not used to bury the person at the time he died but rather to bury his bones after the body has decomposed. This was, seemingly, the practice in Eretz Yisrael where people were buried in Kuchin; after the body had decomposed the bones were collected and placed in a ceder box, which was buried (see Tur (Y"D 403)).

Kol Tuv,

Yonasan Sigler

This is not a Psak Halachah