Come on, no Big Bird?!
Visual Size Comparison Of Flying Creatures From Yesteryear And Today

This is a visualization created by Global Data comparing the sizes of various flying creatures both extinct and extant, but mostly extinct because Mother Nature made all the wildest models back in the day. Don’t get wrong, she’s still got some pretty crazy designs in existence, but she’s definitely grown out of her ‘bigger is better’ phase. Now if you’ll excuse me, I have a date with a time machine, some poor decision making, and being fed to some giant baby birds.