Free How to Build a Dinosaur by Jack Horner Page B

travel, I would have probably chosen some desolate, eroding, fossil-rich locale in Mongolia if I had my pick of destination. Then, as now, dinosaurs were my work, hobby, and obsession. I would have been happy to learn how to make and study thin sections if I had found someone closer to work with. But paleohistology was an exceedingly small field and Armand de Ricqlès, at the Sorbonne , was my best chance as a teacher and mentor.

INSIDE THE BONES
    Paleohistology, essentially the study of ancient tissues, in my case the investigation of the microstructure of dinosaur bone, had picked up speed in the 1980s, when scientists came to see many dinosaurs as warm-blooded. One of the most crucial arguments involved structures called Haversian canals, small tunnels for blood vessels. Some dinosaur bone was riddled with them, meaning that it had the kind of rich blood source that characterizes fast-growing bone in birds and mammals. Cold-blooded reptiles grow differently, and their bone looks different. Dinosaurs were beginning to look much more like ostriches than alligators.
    Other findings were also important in building the case that many dinosaurs were warm-blooded, unlike other reptilians. Population structures, such as the ratio of predators to prey, and parental behavior both suggested dinosaurs were more like ground-nesting birds than any living reptiles.
    By the time Mary was doing her master’s work in the early nineties, we were using new techniques. CT scans of fossils showed us interior structure without doing damage to a fossil. Scanning electron microscopes let us see the smallest details. She was learning and using those techniques and more, and dinosaur paleontology had changed enough that her work did not need to take her to Paris. She collaborated with colleagues outside of paleontology in Montana and elsewhere. And of course, her techniques took advantage of the explosion in computing power that has changed all aspects of science profoundly. It is something of a shock to remember that in the early eighties, e-mail was unknown to most of us, personal computers were just beginning to become popular, and the World Wide Web was nowhere to be seen. We didn’t have cell phones in Paris. In the summers, doing fieldwork, we had no phones. We relied on the ancient technology of walkie-talkies.
    For her dissertation Mary wanted to study load-bearing bones in some of the large two-legged dinosaurs. From work on a T. rex specimen found in 1990 she concluded that the tissue in load-bearing fossil bones would be different than that of bone that did not bear weight. She wanted to test her hypothesis. What led her to go in a different direction was a happy accident, although it didn’t exactly seem like that to her at first.
    In order to study these bones, she was making thin cross-sections for study under a microscope. But bone, even modern bone, is not easy to work with. And fossilized bone, part rock, part preserved bone, part who knows what, was really difficult. So she was having some trouble getting the sections right.
    “I had a friend in the vet lab, a bone histologist who was helping me with a problem I was having making thin sections.” The friend went to a veterinary conference to give a talk on her studies of bone histology in modern animals during the time she and Mary were working on dinosaur thin sections. Among the sections mounted on microscope slides that she took to project on a screen was one of the T. rex , Museum of the Rockies specimen 555, or MOR 555. During the question-and-answer session she was asked what the oldest bone was that she had worked with. Funny you should ask, she said, and showed the slide of the T. rex femur.
    Then, after the session was over, someone in the audience came up to the podium and said, “Do you realize you’ve got red blood cells in that dinosaur bone? ”
    The result, Mary said, was that Gail “called me up as soon as she got back. And she had me come over and look at