Spirit Yandusaurus is a skin for the dinosaur Yandusaurus, this skin could be obtained in the 2017 Easter Event on Gallus Island.
( This skin is obtainable through trading, but as it was easily obtainable much like the other 2017 Easter skins it is unlikely to hold much value in trading. )
Yandusaurus Base Model by: Erythia
Skin by: Wendigo_King and Mr_Fantasia
Fun Fact: The "Spirit Yandusaurus" was originally a different model know as "Sea Spirit Yandusaurus" but with need for more skins in the 2017 Easter Event and other reasons, the model was recolored / edited to be a purple/pink coloration, and then once more edited by Mr_Fantasia into the current coloration you see today.