Do all mammals have reallly have tribosphenic design molars?
From wikipedia
What about Tachyglossidaes including the Echidna which seems to have no teeth?
This is the link you want: http://en.wikipedia.org/wiki/Molar_(tooth)
It’s also the link from which your quote was taken.
You owe me one. 
The tribospehnic design is thought to be primitive (i.e., plesiomorphic) in mammals, but has been modified by various lineages. You can see all manner of variations in molar structure here.
Thanks.
Another mammal question:
Were morganucodontids the line that survived?
That is from National Geographic.
http://magma.nationalgeographic.com/ngm/0304/feature1/index.html?fs=www7.nationalgeographic.com
Nope. They only lasted through about the middle of the Jurassic. The sister clade to Morganucidontidae split into Docodonta and Symmetridonta; the latter lineage is the one that survived to produce cats and rats and elephants.
No unicorns? 