Like any historian worth his salt, I've had to do more than a little delving into tombs, crypts, catacombs, and burial mounds when I needed to find a specific relic or tome. I think we can all agree that a minor but annoyingly common pest in our historical research are all the damn reanimated skeletons wandering around all the time. Fortunately, they're quite easy to dispatch, but they still interrupt my work all the time.
But I recently realized something odd: every skeleton I've ever seen has been from men. There may possibly have been some mer skeletons in there too; without the pointy ears, I'd have to consult an anatomist on what the differences are between man and elf bone structure. Regardless, I've never seen a skeleton with a tail indicating that they were previously Argonian or Khajiit when they were alive. In fact, I once saw a necromancer raise a skeleton from a recently slain Argonian, but the skeleton appeared to be that of a man!
So I'm turning to you, my fellow historians. In all the historical documents at our disposal, is there some reason why all skeletons are men? Are necromancers all racist for some reason?
This is naturally a topic of great interest to archaeologists. The answer is actually very simple: the so-called "beast races" have biodegradable skeletons! The chemistry of this is beyond my expertise, but it has some very interesting consequences for soil morphology analysis, especially as the decomposition process has some impact on the dating methods that are currently in use. It also, incidentally, has an impact on the alchemical properties of the bonemeal byproducts, which do remain intact through decomposition, and are the cause of some of the variations that we see in bonemold armor in parts of southern Morrowind.
The one anomalous exception in the archaeological record dates to the late sixth and early seventh centuries of the Second Era, when the combined influence of necromancer activity and intervention from Molag Bal had an effect on post mortem morphological fields. Argonian/Khajiiti corpses from that era underwent a magical distortion that caused a widespread physiological homogenisation, so that physical remains absorbed some properties of other nearby remains. This distortion effect lasted as much as a century or so in some parts of Tamriel; the effect was most pronounced in Cyrodiil, thanks to direct influence from the notorious necromancer Mannimarco.
But other than that, and perhaps a very few other physiological anomalies (such as the physiological distortions that we see in late Third Era skeletons on Vvardenfell, caused by the Blight), the beast races leave only chemical remains in the archaeological record. That's also why we have essentially no idea what the bird men of the Merethic looked like.
The reason was outlined by the Guards during the attempted beheading if the Dovakin... bodies of foreigners are shipped back to their home land.
Source the book of Skyrium