XTO Energy (XTO)

AGREEMENT AND PLAN OF MERGER

This Amendment No. 3 to the Agreement and Plan of Merger (the “Amendment”) is entered into as of March 31, 2005 to amend the Agreement and Plan of Merger dated January 9, 2005, as amended by Amendment No. 1 to Agreement and Plan of Merger (“Amendment No. 1”) dated February 3, 2005, and as further amended by Amendment No. 2 to Agreement and Plan of Merger (“Amendment No. 2”) dated March 22, 2005, by and among Antero Resources Corporation, a Delaware corporation (the “Company”), XTO Energy Inc., a Delaware Corporation (“Parent”), XTO Barnett Inc., a Delaware corporation and wholly owned subsidiary of Parent (“Merger Subsidiary”) and XTO Barnett LLC, a Delaware limited liability company and wholly owned subsidiary of Parent (“LLC Sub”). The Agreement and Plan of Merger as amended by Amendment No. 1 and Amendment No. 2 is referred to herein as the “Merger Agreement”. Capitalized terms used in this Amendment and not otherwise defined have the meanings given them in the Merger Agreement.

AGREEMENT AND PLAN OF MERGER

This Amendment No. 2 to the Agreement and Plan of Merger (the “Amendment”) is entered into as of March 22, 2005 to amend the Agreement and Plan of Merger dated January 9, 2005, as amended by Amendment No. 1 to Agreement and Plan of Merger (“Amendment No. 1”) dated February 3, 2005, by and among Antero Resources Corporation, a Delaware corporation (the “Company”), XTO Energy Inc., a Delaware Corporation (“Parent”), XTO Barnett LLC, a Delaware limited liability company (“LLC Sub”) and XTO Barnett Inc., a Delaware corporation and wholly owned subsidiary of Parent (“Merger Subsidiary”). The Agreement and Plan of Merger as amended by Amendment No. 1 is referred to herein as the “Merger Agreement”. Capitalized terms used in this Amendment and not otherwise defined have the meanings given them in the Merger Agreement.

AGREEMENT AND PLAN OF MERGER

This Amendment No. 1 (the “Amendment”) to Agreement and Plan of Merger (the “Merger Agreement”) dated January 9, 2005, by and among Antero Resources Corporation, a Delaware corporation (the “Company”), XTO Energy Inc., a Delaware Corporation (“Parent”), and XTO Barnett Inc., a Delaware corporation and wholly owned subsidiary of Parent (“Merger Subsidiary”), is entered into as of February 3, 2005. Capitalized terms used in this Amendment and not otherwise defined have the meanings given them in the Merger Agreement.

AGREEMENT AND PLAN OF MERGER

THIS AGREEMENT AND PLAN OF MERGER (this “Agreement”), dated as of January 9, 2005, is made by and among Antero Resources Corporation, a Delaware corporation (the “Company”), XTO Energy Inc., a Delaware corporation (“Parent”), and XTO Barnett Inc., a Delaware corporation and a wholly-owned subsidiary of Parent (“Merger Subsidiary”).