How to convert "1985-02-07T00:00:00.000Z" (ISO8601) to a date value in Oracle?
to_date converts the input to a DATE type which does not support fractional seconds. To use fractional seconds you need to use a TIMESTAMP type which is created when using to_timestamp
pst's comment about the ff3 modifier is also correct.
"Constant" values in the format mask need to be enclosed in double quote
So the final statement is:
select to_timestamp('1985-02-07T00:00:00.000Z', 'YYYY-MM-DD"T"HH24:MI:SS.ff3"Z"')from dual;