A new examination of skulls from the royal cemetery at Ur, discovered in Iraq almost a century ago, appears to support a more grisly interpretation than before of human sacrifices associated with elite burials in ancient Mesopotamia, archaeologists say.

Palace attendants, as part of royal mortuary ritual, were not dosed with poison to meet a rather serene death. Instead, a sharp instrument, a pike perhaps, was driven into their heads.

Archaeologists at the University of Pennsylvania reached that conclusion after conducting the first CT scans of two skulls from the 4,500-year-old cemetery. The cemetery, with 16 tombs grand in construction and rich in gold and jewels, was discovered in the 1920s. A sensation in 20th century archaeology, it revealed the splendor at the height of the Mesopotamian civilization.

The recovery of about 2,000 burials attested to the practice of human sacrifice on a large scale. At or even before the demise of a king or queen, members of the court — handmaidens, warriors and others — were put to death. Their bodies were usually arranged neatly, the women in elaborate headdress, the warriors with weapons at their side.

C. Leonard Woolley, the English archaeologist who directed the excavations, a collaboration between Penn and the British Museum, eventually decided that the attendants had been marched down into burial chambers, where they drank poison and lay down to die. That became the conventional story.

Among the many human remains, only a few skulls were preserved, and those had been smashed into fragments — not in death but from the overburden of earth accumulating over the centuries to crush skulls flat as pancakes. That had frustrated earlier efforts to reconstruct the skulls.

In planning for a new exhibition of Ur artifacts, which opened Sunday at Penn’s Museum of Archaeology and Anthropology, Richard L. Zettler, the co-curator and a specialist in Mesopotamian archaeology, said researchers had taken CT scans of skull bones of a woman and a man. From those they obtained three-dimensional images of each fragment and so determined where the pieces fit.

The researchers, led by Janet M. Monge, a physical anthropologist at Penn, applied forensic skills to arrive at the probable cause of death in both cases.

There were two round holes in the soldier’s cranium and one in the woman’s, each about an inch in diameter. But the most convincing evidence, Dr. Monge said in an interview, were cracks radiating from the holes. Only if the holes were made in a living person would they have produced such a pattern of fractures along stress lines. The more brittle bones of a person long dead would shatter like glass, she explained.

Dr. Monge surmised that the holes were made by a sharp instrument and that death “by blunt-force trauma was almost immediate.”

Ritual killing associated with a royal death was practiced by other ancient cultures, archaeologists say, and raises a question: Why would anyone, knowing their probable fate, choose a life as a court attendant?

“It’s almost like mass murder and hard for us to understand,” Dr. Monge said. “But in the culture these were positions of great honor, and you lived well in the court, so it was a trade-off. Besides, the movement into the next world was not for them necessarily something to fear.”

Dr. Zettler said the new research also turned up evidence that the bodies of some victims had een heated, baked not burned, and treated with a compound of mercury. It was a primitive mummification process, not as advanced as techniques in contemporary Egypt.

“This was just to keep the bodies from decomposing during extensive funerary ceremonies,” he said.

On a brighter note, Dr. Zettler said the site of the ancient city-state Ur, near present-day Nasiriyah in Iraq, has been spared in the recent warfare that brought damage and looting to other ancient digs. Ur is protected within the perimeter of an air base, which was recently handed back to the Iraqis.