Here's how to jump back from crow pose into chaturanga. This video is 3 mins, 42 seconds, and here's the breakdown if you're not up for watching the whole thing:
:12 Tips for crow pose
1:32 Instructions & Prep for charging legs back to chaturanga
2:14 Really good ab exercise you can do to strengthen the core so you can charge the legs back from crow.
I hope that was helpful! Please let me know if you have any questions, or have a tutorial request.