Hmmm, I thought the mummiform (man-shaped) type of coffin that we associate with Egypt didn't appear until the XVII dynasty, a few years before the New Kingdom started. The Middle Kingdom sarcophagi that I've seen elsewhere were simple rectangular boxes, with hieroglyphics and a pair of eyes painted on the outside. Do you think the picture from that article was mislabeled?
And I resent them saying that the Middle Kingdom was a little-known era. It may not have been as glamorous as the Old Kingdom with its pyramids, or the New Kingdom with all the accomplishments of its pharaohs, but the best Egyptian literature was written during the Middle Kingdom. Nowadays, if you learn hieroglyphics, it's likely you'll be given Middle Kingdom texts to study/practice with. And we certainly know more about the Middle Kingdom than we do about any of the intermediate periods, or the archaic era before the first pyramid was built.
after I posted this last night I spent a little time browsing for more info on egyptian wooden coffins, you may well be correct on the ostentatiousness of the one pictured and its origins time-wise,, I saw a couple other pieces that were much less ornate and box-like.
:') I think there are some things which may have skewed previous data; the Middle Kingdom only lasted 400 years, built with mud brick and very soft stone (and pilfered Old Kingdom work in larger, harder stone), doesn't appear to have been a wealthy era for Egypt, and ended in a pretty grim manner.