Personalized Dinosaur 3rd Birthday Toddler T-Shirt. A dinosaur apatosaurus (or brontosaurus to the grandparents) stands tall over the 3 for the second birthday. Happy third birthday to the three year old! A toddler-soft cotton tee in look-at-me, big kid colors. 4.5 oz., 100% combed ringspun cotton. White is sewn with 100% cotton thread. Topstitched rib crew neck. Double-needle stitched sleeves and bottom hem. Shoulder-to-shoulder taping.