[From _The New York Times_, July 1, 1993]


Scientists Believe Blood Cells

in Tyrannosaurus Rex May

Lead to Traces of DNA


A Montana paleontologist and his colleagues believe they have found

red blood cells in the fossilized leg bone of a Tyrannosaurus Rex

and say they have high hopes of extracting DNA from the dinosaur’s


The discovery of the putative dinosaur blood cells has not yet been

submitted to a scientific journal or independently confirmed but was

reported two weeks ago by the National Science Foundation, which has

financed the exploratory project. Jack Horner, a paleontologist at

Montana State University who directed the investigation, said in an

interview yesterday that his group hoped to find matches between

gene fragments left in the preserved blood cells with comparable DNA

segments from modern crocodiles or birds.

“If we’re lucky enough to find matches,” he said, “they could go a

long way toward showing what the relationship between dinosaurs and

birds might be. We’re not there yet, but we think we’re getting


The femur, or leg bone, that Mr. Horner’s group is studying is part

of an unusually well-preserved tyrannosaur fossil, more than 65

million years old, which they found and excavated from the Hell

Creek Formation in eastern Montana three years ago. The apparent

blood cells were discovered by Mary Schweitzer, Mr. Horner’s

graduate student who was investigating the cell structure of

fossilized bone and marrow tissue.

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New Climate of Belief

In the past, few paleontologists or molecular biologists believed

that biological material could survive for millions of years without

becoming mineralized, thus losing its organic molecular structure.

The survival of any intact DNA, which ordinarily decays with time,

seemed even less likely. But the recent discovery of organic

material and even fragments of DNA in ancient plant and animal

fossils has changed opinions.

“Two years ago I would have called this baloney,” said Dr. Raul J.

Cano of California Polytechnic State University at San Luis Obispo,

a molecular biologist who has himself extracted DNA fragments from

fossilized insects and plants millions of years old.

Told of Mr. Horner’s belief that blood cells have survived in a

tyrannosaur bone – and that they may contain dinosaur DNA fragments

– Dr. Cano said: “It’s certainly plausible. We have seen similar

things ourselves, and there are reports from other investigators of

the finding of surviving biological material inside fossil dinosaur

bones, especially in the deep bone cortex, which seems to be

somewhat protected from mineralization.”

Earlier this month, Dr. Cano and his associates reported in the

British journal Nature that they had extracted DNA from a weevil

that had been entombed in amber for 120 million to 135 million


Doubter Grants Possibility

A molecular biologist who has strongly questioned the premise that

appreciable quantities of DNA could survive for very long periods is

Dr. Russell Higuchi of Roche Molecular Systems in Alameda, Calif.

But Dr. Higuchi said yesterday that it seemed possible that Mr.

Horner’s group, had actually seen dinosaur blood cells.

Although Dr. Higuchi said he remained doubtful about the survival of

dinosaur DNA, particularly in a fossil that was probably exposed to

water, “we ourselves speculated 10 years ago that if dinosaur DNA

survived at all, it might be found” deep inside a fossil bone.

Mr. Horner said that microscopic examination of a thin slice through

the dinosaur bone revealed that although its outer layers were

mineralized the bone itself, brown in color, remained more or less

intact in the interior of the marrow cavity.

“Mary found spherical structures that appear to be nucleated red

cells inside the blood vessels running through the bone, right where

you’d expect to find blood, if it’s there,” he said. “Since then

we’ve been trying everything we can think of to show that they’re

not blood cells, but they still seem to be the real thing.”

Fears of Contamination

Part of the science foundation’s grant to Mr. Horner’s group went

for laboratory equipment to conduct a polymerase chain reaction, a

technique that can single out a lone molecular fragment of DNA and

make enough copies so it can be analyzed using standard methods.


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“The biggest problem is contamination of the fossil by foreign DNA,

“Mr., Horner said. “There’s lots of it there, The real trick is in

identifying something that is not a contaminant. This is why we are

looking for matches with crocodile DNA, which is not a likely


Mr. Horner says he is certain that at least some original tissue

remains in the fossil because his group has positively identified

collagen in the bone. Collagen is a fibrous protein found in the

connective tissue of animals, which ordinarily decays rapidly except

under special circumstances.

Cheryl Dybas, a spokeswoman for the National Science Foundation,

acknowledged that her agency had intentionally released its report

of Mr. Horner’s progress to coincide with the opening of “Jurassic

Park,” a science fiction movie based on the premise that dinosaurs

might one day be cloned from their surviving DNA.

“We thought it would be a good opportunity to get the word out on 4

of the 10 dinosaur research projects the N.S.F. is funding this

year, including that of Mr. Horner,” Ms. Dybas said.