The chocolate-brown skeleton of the monster is poised menacingly at the north end of the Field Museum’s cavernous Stanley Field Hall, her head cocked to the left, glaring at the most heavily used public entrance to the museum.
After years of hype and hullabaloo, the curtain will finally fall away from this monster named Sue on Wednesday, revealing the biggest, most complete (and at $8.36 million, easily the most expensive) Tyrannosaurus rex fossil ever found.
Without nearly as much fanfare as the made-for-TV unveiling, the Field also will reveal a host of scientific discoveries made while Sue’s fossilized bones were being cleaned and studied.
It turns out that Sue likely would have caught a whiff of those visitors coming in the museum’s door–her skull contained massive olfactory bulbs that would have given her a keen sense of smell.
But the visitors at least would have had a chance to get away. Sue’s foot bones revealed that T. rex wasn’t as fast as some scientists had thought and probably couldn’t even run.
And scientists found in Sue, the best of the 21 T. rex skeletons known to science, yet more evidence linking dinosaurs and birds. Sue, it turns out, has a massive wishbone.
Primarily the work of Field paleontologist Christopher Brochu, the findings raise some tantalizing suggestions about how T. rex, king of the dinosaur carnivores, reigned for some 2 million years.
Sue will be right back on top at 6 a.m. Wednesday during the scheduled unveiling of the finished, mounted skeleton, an event set to be carried live on several morning news shows. Nationally, the “Today Show,” “Good Morning America” and CNN have indicated they plan to carry the unveiling live. All the local television morning news shows will be present, too, along with BBC radio and a Japanese television network.
For the occasion, the Field brought in many of the people important to the fossil’s history since it was dug out of a South Dakota cliff in 1990. Not the least of whom is Susan Hendrickson, who found the fossil (which is named after her). Peter Larson, the paleontologist Hendrickson worked for, also will be there. In a dispute that arose over ownership of the land Sue was found on, Larson was convicted and sent to prison, after a controversial federal trial, on two minor charges unrelated to the fossil.
The skeleton they found not only promises to be a huge draw for the museum, but it also has already proved to be a scientific treasure trove. Sue has a number of features never before observed in the other T. rex skeletons. The new information underscores what scientists for the last several years have been postulating: that dinosaurs are closely related to birds.
“We saw that the [nerve] pathways leading to its brain are a lot more birdlike than I would have imagined,” said Brochu, an expert in crocodile fossils and anatomy. “But there are some crocodilian similarities in the cranial cavity, too, so it is an interesting mix.”
The huge olfactory bulbs suggest T. rex was a species that relied a great deal on its sense of smell. That attribute, however, can’t settle differences of opinion as to whether T. rex was primarily a predator or scavenger. Both need good noses.
Abnormal bone growth on Sue’s tail formed perfect molds around muscle tissue that now give science its first look at what T. rex muscle looked like. Markings of muscle attachments on Sue’s legs show that, massive as they are, the leg muscles resemble those of birds.
The scientific data collected so far, however, does not support some tantalizing earlier interpretations of her bones, formed initially as curators removed rock from the fossil. There is no way of knowing whether T. rex was warm- or cold-blooded, for example, Brochu said.
And holes found in Sue’s skull were not made by the bite of another dinosaur in a fight, as earlier thought, but are the result of disease. There also is no evidence, said Brochu, that Sue had serious injuries early in life that would indicate she had to be protected by other animals, presumably family, while she healed, another early theory gleaned by others from her bones.
Indeed, though the Field continues to refer officially to Sue as a “she,” Brochu said there is not even evidence to say whether Sue was male or female.
“As far as I am concerned, Sue is an `it,'” he said. “So far we have no means at our disposal to determine the gender of dinosaurs.”
One thing that is clear, said John Flynn, the museum’s chief paleontologist, is that Sue as an individual was a very old member of her species when she died.
“Here is a very, very old dinosaur that just got sick and died after a long, active life,” Flynn said, “though we have no way of knowing exactly how old. During her life, she survived a lot of diseases and injuries.
“We know turtles and crocodiles can live to 150 years, and they are cold-blooded. We know some birds, which are warm-blooded, can live for many decades. My guess is that dinosaurs could live for decades, some 100 years or more.”
Later this year, Flynn said, upon publication of a scientific monograph on Sue written by Brochu, the museum will invite scientists from other institutions to make more detailed and specialized studies of Sue.
Of course, Sue isn’t ever likely to reveal all of T. rex’s secrets.
The museum’s educational and exhibits departments are using what can and cannot be learned from Sue’s bones for exhibits related to the fossil on the second-floor balcony overlooking her bones on the main floor.
“We decided to bring up these issues to show visitors the differences between scientific fact, theory and speculation,” said Barbara Ciega, a senior exhibit developer at the museum.
“As an example of fact, we know that Sue is the largest and most complete T. rex fossil ever found, with 90 percent of her bones intact.
“We show how some theories can be so strong as to be as good as fact. All architectural design principles are theory, but they are theories so reliable that they hold up the buildings we live in and allow the airplanes we fly in to remain aloft.
“With Sue, we demonstrate theories such as dinosaurs and birds being closely related. We also use Sue to show scientific speculation on things that we will never have a chance of truly knowing, such as what colors dinosaurs were.”
The second-floor exhibits also will contain portions of Sue’s actual bones that are too heavy to include in the mounted skeleton, including the skull and a portion of the tail. (The head atop the mounted skeleton is a lightweight plastic replica made from molds of the real fossil.)
There will be replicas of some bones that museum visitors will be allowed to touch and feel, including the tip of Sue’s tail, her right forelimb and her wishbone.
A fleshed-out portrait of Sue, by Denver artist John Gurche, hangs in a key position on the second floor overlooking the mounted fossil. In the portrait, Sue strikes the same pose as the skeleton, glancing up from a duck-billed dinosaur she is eating.
It took 12 people 30,000 hours to remove the fossilized bone from rock. The mount will be moved in three to five years to a permanent display in the current Life Before Time evolutionary exhibits.
“We’ll be able to put her in a more Cretaceous environment there than we can do in Stanley Field Hall,” said William Simpson, chief of the Field’s preparation labs.
When it came time to put the cleaned bones together for display, the Field hired one of the acknowledged masters of that work, Phil Fraley Productions of New Jersey.
“We work on reflecting scientific thought accurately, but we always try to maintain a subtlety of the fossil’s pose,” said Phil Fraley, owner of the firm. “I always want to convey the sense of motion and drama of the specimen.”
Sue’s tail is held off the ground, the position paleontologists now believe T. rex assumed while getting around.
To make the steel framework for the bones, engineers designed a structure that can carry the weight of the bones and not create “point loads” that could fracture the fossil pieces.
Metalworking craftsmen shaped each armature of the frame to the contours of the bone it must hold. In some cases, the structure is similar to the setting on an engagement ring.
“On the vertebrae,” he said, “we used the jewelers’ techniques, with tapered prongs adhering to the shape of the bone. The prongs grip each vertebra like a precious stone.”
The mount is designed so that any one bone can be taken from the finished skeleton for scientific study without disturbing the rest of the skeleton.
The trickiest part, Fraley said, is finding an accurate and dramatic pose, then getting every joint in the skeleton to conform to the pose.
“We try to capture the movement of the animal down to 1/1,000th of a second, a freeze frame of a moment in its life,” he said.
“With Sue, we have her posed as though she was bent over in some little activity and then disturbed, so that she is looking up. In this case, she is looking at the museum’s main entrance, as though the entering visitors are the trigger of her disturbance.
“But that’s as much of the story as we want to tell. We think it is better from there on for children and adults to fill out the story in their own imaginations.”
