When Were Flightless Birds Created?

Here's a recent thought from my daughter, Hannah:

We know that birds and fish were created on Day 5 (Genesis 1:20-23). And we know that land animals were created on Day 6 (vv. 24-25).

But what about flightless birds, like ostriches, emus, and penguins? Are they still grouped with the Day 5 animals, since they are "winged birds" (v. 21), even though they don't "fly above the earth"? Or are they one of "all the creatures that move along the ground" (v. 25), and thus were Day 6 animals?

What do you think? When were flightless birds created?


Genesis 1:20-15
 ²⁰ And God said, “Let the water teem with living creatures, and let birds fly above the earth across the vault of the sky.” ²¹ So God created the great creatures of the sea and every living thing with which the water teems and that moves about in it, according to their kinds, and every winged bird according to its kind. And God saw that it was good. ²² God blessed them and said, “Be fruitful and increase in number and fill the water in the seas, and let the birds increase on the earth.” ²³ And there was evening, and there was morning—the fifth day.
 ²⁴ And God said, “Let the land produce living creatures according to their kinds: the livestock, the creatures that move along the ground, and the wild animals, each according to its kind.” And it was so. ²⁵ God made the wild animals according to their kinds, the livestock according to their kinds, and all the creatures that move along the ground according to their kinds. And God saw that it was good. 

Related Link:

• The Cell and the Origin of Life

image courtesy of imc via sxc.hu