Black standard chick, clean legs, rose comb--ideas on breed?

[TxChickieFan]

I was at my brother's house yesterday and was looking at his chicks. He picked up 5 black (with some yellow) chicks from TSC about 7 weeks ago. They were unlabeled, and he assumed they were likely black Australorps.

Fast forward a few weeks, and they seem to have rose combs rather than single combs. Any ideas on what the breed might be?

Here's one of the chicks that had more yellow as of 4/6. I'll try to get him to send me a current pic later today or tomorrow (he's got a kid baseball tournament scheduled for today).

Thanks for any ideas!

Edited to add, maybe a black Wyandotte?

 

[my gang eats grass]

Do they have bright white earlobes?