Why does the author mention the specimen preserved in the birth canal?

Whydoestheauthormentionthespecimenpreservedinthebirthcanal?_____

Toillustr atethattheembryofossilsarequiteadvancedintheirdevelopment

Toexplainwhythefossilsarewellpreserved

Toindicatehowtheichthyosaursdied

Toprovethatichthyosaursaremarineanimals

答案及解析：第三段中提到保存在产道中的标本,是为了说明胚胎发育的程度很高。