harles Sternberg’s ;e Life of a Fossil Hunter
provides a fascinating picture of the early days
of paleontology. He began searching for fossils
in western Kansas in the 1870s, digging them
up and shipping them to east-
coast scientists. Western North America
was rich in fossils, and in the years that
followed, Sternberg and others uncovered a
treasure trove that formed the foundation of
American paleontology.
Yet early paleontologists merely scratched
the surface of the fossil record. Equipped with
sharp eyes, picks, shovels and horse-drawn
wagons, they could only recover the most obvious fossils that were in good enough condition
to excavate. ;eir clues to the ages of fossils
were limited to the layering of rocks and the
presence of other fossils. And the only data
they collected were the fossils themselves and
field notes that sometimes weren’t adequate to
guide later scientists back to the original site.
Although modern paleontologists still use
many time-tested techniques, such as covering newly discovered fossils with a protective
layer of plaster, they also rely on new technologies, such as GPS receivers to pinpoint their
location, digital cameras, satellite phones and
laptop computers. Lasers and other optical
technologies are playing a growing role. Laser scanners can
record the three-dimensional contours of fossil bones in the lab
and dinosaur footprints in the field.
Laser-scanned data can be manipulated in three-dimensional computer models to study the biomechanics of long-extinct
animals. Lasers and optical systems also play background roles
in instruments that date rocks, analyze fossil chemistry and
find traces of proteins in dinosaur fossils. Your 5-year-old may
not think lasers and optics are as cool as dinosaurs, but these
tools play a critical enabling role in helping paleontologists to
learn more about all kinds of fossils.
C
Where dinosaurs walked
Lasers are helping paleontologists to preserve and understand
the best records that scientists have to track the behavior of
dinosaurs and other extinct animals—the footprints that those
animals made in mud or soft soil that later turned into rock.
;e spacing and depth of footprints tells us how animals
walked or ran, and how massive they were. Similar tracks made
parallel to each other show that the animals lived in groups or
herds. Like skilled nature guides, paleontologists who study
footprints can identify animals and their behavior from the
tracks. Footprint specialists even assign them two-part names
like the genus and species names given to fossil bones.
Dinosaur tracks are the best-known fossil footprints, but they
can also be the most troublesome. One problem is their sheer
Digital reconstruction of the laser-scanned
Tyrannosaurus rex at the Carnegie Museum.
A team from Maglev Inc. in McKeesport, Pa.,
scanned the skeleton in its original upright
position (inset, top left), then manipulated the
scanned data (bottom left) to build a digital
version in the more realistic position at top.
size. ;e most massive dinosaurs, the long-necked, elephant-bodied sauropods such as brachiosaurus, left footprints that
were more than a meter across. Another is that trackways (a
fossilized set of impressions left in the soft earth) convey more
information if they show a series of strides taken by the dinosaur, which can span tens of meters, an area hard to survey in
the field and too large to fit in the laboratory.
Both the size and the number of tracks made by the biggest
dinosaurs have complicated the study of one of the best-known
and best-preserved trackways, discovered 70 years ago by
Roland T. Bird of the American Museum of Natural History
in New York. After finding some tracks along the Paluxy River
in Glen Rose, Texas, he exposed more by digging along the
bank and diverting water from submerged footprints. ;en he
photographed the tracks and meticulously mapped them on a
large roll of paper to trace the paths of individual dinosaurs.
Bird was particularly intrigued by a set of tracks that he
thought showed a large predatory dinosaur stalking or chasing
large plant-eaters—an idea that remains controversial. He
excavated those tracks and shipped them back to the American
Museum, where they have been a popular display for decades.
Other tracks were excavated for the Texas Memorial Museum
in Austin, but most were left in place.
Photographs and sketches are easier to handle than dinosaur footprints themselves, but they don’t directly measure
the depths or contours of tracks. ;at’s where lasers come in.
