``` python import pandas as pd ind = pd.date_range(start="2000-01-01", freq="D", periods=10) datetimes = [ts.to_pydatetime() for ts in ind] datetime_s = pd.Series(datetimes) datetime_s.dtype # object df = pd.DataFrame({'datetime_s':datetime_s}) print df.dtypes #datetime64 ``` Shouldn't Series upconvert to datetime64 since the DataFrame columns do?