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July 29 (Reuters) - LandAmerica Financial Group LFG.N, a large U.S. title insurer, posted a wider-than-expected quarterly loss as residential mortgage originations and commercial revenue declined, and the company slashed its dividend by 83 percent.

The insurer posted a loss of $50.0 million, or $3.29 a share, compared with earnings of $7.9 million, or 42 cents a share, last year. Total revenue fell 29 percent to $712.4 million.

Analysts on average had expected the company to post a loss of 71 cents a share, before special items, according to Reuters Estimates.

"Adverse claims development from past periods has masked the significant cost reductions we have achieved over the past six quarters leading to a disappointing bottom line," Chief Executive Theodore Chandler said in a statement.

As estimated by the Mortgage Bankers Association, mortgage originations fell 25.1 percent in the second quarter, the company said.

The company slashed its quarterly dividend to 5 cents a share from 30 cents.

Shares of the company closed at $16.72 Tuesday on the New York Stock Exchange. (Reporting by Ratul Ray Chaudhuri in Bangalore; Editing by Deepak Kannan)