In Yellow Freight System, Inc. v. Workmen's Compensation Appeal Board (Madara), 56 Pa. Commw. 1, 423 A.2d 1125 (Pa. Cmwlth. 1981), the court determined that if an employer fails to file an answer to a claim petition or files an untimely answer, he is precluded from presenting any evidence and the matter is to be decided "on the basis of the petition and evidence presented." Yellow Freight, 423 A.2d at 1127, citing, 77 P.S. 821.