Cairn Energy USA S-4 Registration of securities issued in business combination transactions

EXHIBIT 12.1

Alta Mesa Holdings, LP
Ratio of Earnings to Fixed Charges

	2010		2009			2008		2007			2006
			(dollars in thousands)
Earnings:
Net income (loss) before tax	$	14,231	$	(50,037	)	$	36,880	$	(27,476	)	$	9,853
Fixed charges:
Interest (1)		23,981		11,949			9,212		9,010			9,741
Earnings before fixed charges		38,212		(38,088	)		46,092		(18,466	)		19,594
Fixed charges:
Interest (1)		23,981		11,949			9,212		9,010			9,741
Total fixed charges	$	23,981	$	11,949		$	9,212	$	9,010		$	9,741
Ratio of earnings to fixed charges		1.59	NA				5.00	NA				2.01

(1) Interest expense includes interest on debt, amortization of discount on debt, and an estimate of the interest expense portion of rent expense.