He placed them into modern groups, making them ancestral to today's worms, jellyfish, and other creatures, and thus failed to appreciate their distinctness.

沃尔科特用现代的办法来对它们进行分类，把它们看成为今天的蠕虫、水母和其他生物的祖先，因此没有认识到它们的不同之处。

It saw the rise and spread of the  first of the major animal groups that were, well, recognizable as animals - with  body plans that resemble modern groups today.

它见证了第一个主要动物群体的兴起和传播，这些动物群体被认为是动物，其身体结构与今天的现代群体相似。