What was going on when I was born?

Some of the big names on Wall Street - all major stockholders in the Marathon Oil Company - are lining up on opposite sides of the fence on the question of whether Marathon should complete a $6 billion merger with the United States Steel Corporation. Marathon's stockholders are scheduled to meet Thursday in the company's Findlay, Ohio, headquarters, to vote on the merger, and a spot-check of leading shareholders showed yesterday that the outcome is far from certain. Even whether the meeting will be held is a cliffhanger. Judge Carl Rubin of United States District Court in Cincinnati is reviewing 11 class-action suits by Marathon stockholders, including the Dreyfus Fund, which controls 700,000 shares, seeking to block the meeting on the ground that the merger terms are too low. Whether Judge Rubin will hold up the meeting is still in doubt.

SOME time this month, the woodchuck wakes for good. Instead of emerging from its burrow for a brief look-see, as it is apt to do on Feb. 2 or any other randomly chosen day in midwinter, the woodchuck - along with bats, ground squirrels, hedgehogs, dormice and several other rodents and insectivores of cold and temperate zones -has come to the end of his winter hibernation and rejoins the world of the full-time mammals. Unlike, for example, bears, which merely doze and can awaken suddenly on provocation, true hibernators shut down shop for the duration. The metabolism of these animals drops to nearly nothing. Body temperature falls nearly to freezing. Heartbeat slows - in ground squirrels, for example, from 350 beats per minute to three or four. Stuffed with fat stored in the summer, they doze through months of snow and ice, which might otherwise starve them to death by depriving them of forage. In spring they emerge, thinner than before but ready to start a new season.

Because of an error by the New York City Department of Health, a listing of restaurant violations on Feb. 28 incorrectly described the status of the Roy Rogers restaurant at 1286 Broadway. The restaurant was found free of violations.

The Metropolitan Transportation Authority is close to a deal with a Japanese company for the purchase of 325 subway cars, sources close to the talks said yesterday. It would be the first purchase of foreign-made passenger cars for the New York system. The talks with the manufacturer, Kawasaki, are only one of several sets of negotiations with foreign manufacturers. If successfully completed, the negotiations could result in the purchase of 1,150 foreign-made cars for the IRT system over the next five years.

Stanley Kramer, one of Governor Carey's policy makers on transportation issues, has left the administration to run for the House of Representatives. Mr. Kramer, who resigned Feb. 1, is the first of Mr. Carey's appointees to leave office since the Governor said he would not run again. Roger Vaughan, the director of the Office of Developmental Planning and Mr. Carey's expert in the area of telecommunications, will be self-employed after May 7. Mr. Vaughan, who has worked for Mr. Carey since July 1980, has two book contracts. And Jill Schuker, Mr. Carey's press secretary, is expected to leave soon. ''There is nothing definite at this point,'' she said, but she is known to have several job offers.

The world's two largest auto makers, the General Motors Corporation and the Toyota Motor Company, are discussing joint production of small cars in the United States, Toyota said today. In a three-sentence statement, the Japanese company confirmed that on March 1, Eiji Toyoda, president of Toyota, and Roger B. Smith, chairman of G.M., had met in New York to discuss the possibilities of such a venture. ''The two companies have committed themselves to give further consideration to this possibility,'' the statement said. ''It is too early for any additional announcement.'' (General Motors, in Detroit, confirmed the Toyota announcement in an equally brief statement. (In Grand Rapids, Mich., F. James McDonald, president of General Motors, said in a speech that, if an agreement with Toyota were reached, the joint venture would build 400,000 to 500,000 small cars annually, The Associated Press reported. ''It's imperative for us that we be in the small-car business,'' Mr. McDonald added.) The statement by Toyota was apparently prompted by a report of the March 1 meeting in this morning's issue of Nihon Keizai, Japan's leading economic newspaper.

Several leading banks reduced their prime lending rates by half a point, to 16 percent. It was the lowest level for the prime in three months, and hopes rose in banking circles that interest rates would continue to fall. One forecast was for a 14 percent rate within 30 to 45 days. Chase Manhattan also reduced its residential mortgage rates by a quarter point. (Page A1.) Stock prices plunged in active trading as worry over the weakening economy mounted. The Dow Jones industrial average dropped below the 800 level for the first time in almost two years, closing 11.89 points lower, at 795.47. Analysts predicted a further decline in the Dow, to between 760 and 780 over the next few weeks. (D1.)

Bruce M. Caputo, his campaign for the United States Senate damaged by his inaccurate claims of having been a Vietnam-era draftee and an Army lieutenant, quit the race yesterday. Mr. Caputo wrote out a three-paragraph statement in the morning, and in the early evening his campaign manager telephoned it to news organizations. ''Continuing the campaign,'' Mr. Caputo wrote, ''would only hurt my family, particularly my parents, the voters who have supported me in the past and the political parties which helped me reach the State Legislature, the Congress and the United Nations.'' Three Nominations Open His departure leaves the race open for nominations by the Republican, Conservative and Right to Life Parties of candidates to oppose Senator Daniel Patrick Moynihan, a Democrat.

The Dow Jones industrial average tumbled below the 800 level for the first time in almost two years yesterday as the stock market, under pressure because of the weakening economy, continued its plunge in active trading. The blue-chip barometer, which was up more than 9 points in the first half-hour of trading after the Chase Manhattan Bank and several other banks reduced their prime rate to 16 percent from 16 1/2 percent, closed down 11.89 points, to 795.47. ''Even the near-term prospect of lower interest rates is apparently not enough to offset mounting concern by investors over the deepening recession and the possibility of lower corporate earnings,'' said Monte Gordon, vice president and research director of the Dreyfus Corporation. Inability to Rally Cited Mr. Gordon said that the market's inability to rally successfully indicated the probability of a further decline in the Dow to the 760 to 780 area in the next few weeks.

The Supreme Court today refused to hear a challenge to a law banning the sale of ''drug paraphernalia'' in New York's Westchester County. The law was upheld last year by a Federal appeals court. Without comment, the Justices declined to hear an appeal from that ruling brought by the owners of two shops in the county that sell some of the prohibited items. Today's action comes five days after the Court ruled favorably on another local ordinance regulating the sale of drug-related items. Simultaneously today, the Court also turned down a challenge to a state law in Nebraska that is similar to the Westchester ordinance and that was upheld by a Federal appeals court in Omaha.

DOUBTS By PHILIP M. BOFFEY ALEAK of secret testimony last week put renewed focus on a issue that has arisen repeatedly in recent years -whether exotic laser weapons placed in space would revolutionize warfare or be a costly and ineffective boondoggle. In secret testimony, inadvertently read in open session by a member of Congress, the Defense Department's top research official warned that the Soviet Union is preparing to put a laser weapon in space in the next few years. Such a weapon could threaten to destroy American satellites in geosynchronous orbit, some 22,300 miles above the earth, according to the official, Richard DeLauer, the Under Secretary of Defense for research and engineering. From the fragments of testimony read aloud, it was not clear whether official assessments of Soviet progress on laser weapons have changed. Intelligence sources have predicted for at least two years that the Russians would test a laser weapon in space in the mid-1980's. Such an achievement could have a profound psychological impact, akin to the fears raised by the Soviet launching of Sputnik in 1957, in the opinion of some laser enthusiasts. But whether it would be an important military accomplishment is a matter of sharp dispute.

New York City and State lost their final appeal yesterday in a legal challenge of the 1980 Federal census, which they insist failed to count hundreds of thousands of black and Hispanic residents. The defeat came when the United States Supreme Court refused to hear a city and state appeal, a decision foreordained two weeks ago when the Court declined to hear a similar case involving Detroit. Yesterday's action left intact a ruling last June by a Federal appeals court that a lower-court judge had erred in ordering the Census Bureau to compensate for a ''disproportionate undercount'' of minority groups in the city and state. Lawyers to Try Again City lawyers said they would now go back to the lower courts for a new trial and would challenge the census figures on different grounds.