1. If a tent made of an animal hide contains a corpse, the tent itself becomes Tamei.
2. The Gemara concludes that the "Tachash" used in the building of the Mishkan was a Kosher animal.
3. Similarly, only the hides of Kosher animals may be used in all of the stages of making Tefilin.
4. The Tachash was a creature that had one horn on its forehead.
5. Similarly, the ox offered by Adam ha'Rishon as a Korban had only one horn on its forehead.
A BIT MORE
1. The tent becomes Tamei regardless of whether the hide is that of a Kosher animal or a non-Kosher one.
2. The Beraisa teaches that only a Kosher animal may be used for the "work of Heaven."
3. This includes the parchment on which it is written, the hide used to make the Batim that house the parchment, the sinew and hairs that are used, and the straps of the Tefilin.
4. The Chachamim were unsure about whether it was considered a domesticated or undomesticated animal.
5. This is derived from the verse (in Tehilim) which describes his Korban as "Makrin" without a Yud, implying that it had only one horn.