Naomi took to Instagram on Tuesday to celebrate her fellow supermodel's milestone birthday. She penned, "Happy 50th birthday, little Wagon! I'm proud to welcome you to the fabulous fifties! You're my chosen family and I treasure our decades of sisterhood." Naomi, 53, then recalled some of the memories she shared with the Cosmoss founder. "We've had more unforgettable moments than I care to remember, LOl! Whether it was a photoshoot in Paris, Havana Cuba or our trip to South Africa to visit Nelson Mandela, or riding in the open-top bus as part of the late Queen's Platinum Jubilee…