American Air Parent AMR Posts Loss  DALLAS (Reuters) - American Airlines' parent AMR Corp.  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=AMR.N target=/stocks/quickinfo/fullquote"&gt;AMR.N&lt;/A&gt; on Wednesday posted a third-quarter loss as record-high  oil prices battered its bottom line and threatened to make  fourth-quarter losses even larger.