请教一个英文单词的用法,debris 这个词是碎片的意思,可是为什么animal debris 就是动物粪便的意思呢?

debris
noun [U]
1.pieces of wood,metal,brick,etc.that are left after sth has been destroyed
例：Emergency teams are still clearing the debris from the plane crash.
Several people were injured by flying debris in the explosion.
2.(written or formal) pieces of material that are not wanted and rubbish/garbage that are left somewhere:
例：Clear away leaves and other garden debris from the pond.
the debris of their lunch
第一个意思是碎片,第二个是书面用语,至遗弃的零碎的垃圾、废物等东西.
animal debris是指动物排遗物,简单来说就是动物粪便了,但是我认为准确地还应该包括呼出的二氧化碳、动物死后的遗骸等.