Fossils of the arm of a sloth found in Puerto Rico in 1991,and dated at 34 million years old是主语
made是谓语 it是宾语
the earliest known mammal of the Greater Antilles islands.是宾补
不过本句中found and dated 和made 的用法 有点乱 故是错误的
A.sloth found in Puerto Rico in 1991,and dated at 34 million years old,made it the earliest known mammal of 错 见上面
B.sloth,that they found in Puerto Rico in 1991,has been dated at 34 million years old,thus making it the earliest mammal known on .错 主语是复数 用has
C.sloth that was found in Puerto Rico in 1991,was dated at 34 million years old,making this the earliest known mammal of 但我认为 不对 因为谓语 was dated 与主语不一致
D.sloth,found in Puerto Rico in 1991,have been dated at 34 million years old,making the sloth the earliest known mammal on 我认为 这是正确答案
E.sloth which,found in Puerto Rico in 1991,was dated at 34 million years old,made the sloth the earliest known mammal of 谓语错
整个句子 重新 分析
Fossils of the arm of a sloth,found in Puerto Rico in 1991,have been dated at 34 million years old,making the sloth the earliest known mammal on the Greater Antilles islands
Fossils 是主语of the arm of a sloth是定语,found in Puerto Rico in 1991是定语,
have been dated 是谓语at 34 million years old是状语,
后面是现在分词 短语 作状语
making是现在分词 the sloth是现在分词的宾语 the earliest known mammal on the Greater Antilles islands是宾补