shunosaurs

shunosaurrus is a sauropod from the cretceos period. it is around 50 feet long and 16 feet tall and at aroud 13 tons, it is not a small animal . though it was firly small by sauropod standard. the things that really seperate this anmal fromall othes is the fact that is has  spiked clup at the end of its tail. it also hd aror plating also known as ostrederms wich are tough boy hings on the first layer of of skin. my questions are, why did it have these strange attributesi hnk i ad this o protect itself from predators such s sinraptor(or yanchuanosaurus or metricanthasaurusis have some trouble with those guys)

why ould it have a club?

how thick as its armor?

why did it have such strange featurs?

was it simply convergent evolution?