For the reasons of preserve situation and the difficulty of preparation, there are a lot of synonym and the nomen dubium in the published taxa.

由于化石的保存状况以及标本的修理难度等多种原因，已经发表的材料中包括了大量的同物异名现象以及无效的属种。

youdao

For the reasons of preserve situation and the difficulty of preparation, there are a lot of synonym and the nomen dubium in the published taxa.

由于化石的保存状况以及标本的修理难度等多种原因，已经发表的材料中包括了大量的同物异名现象以及无效的属种。

youdao