Presumption ... there have been plenty of extinctions since the flood.
No it is NOT a presumption, there is more than one place where it is recorded this earth was flooded before Noah's ark. Genesis 1:2, Jeremiah 4:22-26 Nothing survived that flood. and IIPeter 3 says the heaven/earth age that WAS perished by water. You know what, two of these places say that God's children are 'sottish', means stupid, and willingly ignorant in regard to what happened in Genesis 1:2. Job 38 on is asked by God just where was Job when God form/created/ and hung the constellations... as well as that great behemoth.