Why are sprites different sizes in group 'add dragons' filter?

[HeatherMarie]

This has been bugging me for awhile, and now that I've spent literally hours today using the group 'add dragons' filter I figured I'd finally make a topic. When you make a group and go to add dragons through the filter different dragons breeds are vastly different sizes, even when the sprites themselves are relatively the same size (sometimes the smaller sprite is even bigger in the filter). 

 

Examples:

 

 

Adult Olives are much bigger here then the adult Omens

 

 

Adult Deepseas are much bigger then the adult Alt Dark Greens

 

It would be really nice if there were more uniformity in the filter, it's not a huge deal but it does look strange and sometimes it can throw me off, like I think adult sprites are hatchlings because they are so much smaller.

[TJ09]

The rows are all a fixed height. Sprites taller than that are scaled down to fit.