Subject: Are the eggs of monotremes closer to the eggs of birds or reptiles?

Structurally speaking, are monotreme eggs more birdlike or more like 
reptile eggs?  Seeing as mammals evolved from the mammal-like reptiles, I 
would assume the eggs of monotremes were spherical and leathery, like 
turtle or alligator eggs, land eggs of a more basic form.  But it occured 
to me they could possibly be more like bird eggs, as monotremes are more 
advanced than reptiles, as are birds.  Monotremes also have birdlike 
attributes (beaks, so they might also have birdlike eggs.  Actually, for 
all I know, they could be could be far diffent from either bird or reptile.

Re: Are the eggs of monotremes closer to the eggs of birds or reptiles?