Fossils A Time Capsule

It was not long after the predators finished feasting on the corpse of the diseased ornithopod that the first raindrops of an approaching storm began to fall. Many of the animals paused in their activities to greet the cooling wind, and as the rain began to pelt down in earnest, some may have scampered for cover. The bloodsucking flies that had been engorging on the disease-ravaged or-nithopods sought shelter from the encroaching storm and winged their way among the branches of towering Araucaria trees in the nearby forest. Several individuals brushed against glistening deposits of resin and became stuck. They tried desperately to free themselves, but struggling only pulled them deeper into the golden depths, and finally another flow of resin engulfed and sealed them into their amber tomb.

Meanwhile on the nearby floodplain, the small herd of ill dinosaurs continued to graze lethargically on the dry mats of vegetation blanketing the banks of the seemingly placid river, biissfully unaware that upstream, storm runoff was coursing down gullies and ravines and rapidly raising the water level to flood stage. The current began to increase and several sick ornithopods on a small midstream island suddenly became aware that water was lapping around their feet and rising quickly. In the now turbulent flow, heading for shore was not an option, and hampered by their weakened state, they were swept away and drowned. Their bodies were borne downstream to a bend in the river where they floated into an eddy and settled to the bottom. Leaves dislodged by the down-burst and lifted by the wind fell into the river and drifted down around their bodies. Just as fast as the cloudburst began, it ended.

The muddy waters began to flow slower and a layer of sediment settled over the dinosaur bodies together with the leaves and twigs carried in the debris. The sun came out and dried the raindrops as the river subsided back into its normal channel. Insect sounds once again filled the air and life continued.

These events would be uncovered millions of years later when the victims would be revealed to us as fossils frozen in rock and entombed in amber from an extinct araucarian forest. It is from such fossils that we will attempt to unravel a story of struggle, terror, and disease in the Cretaceous, one that involves insects, dinosaurs, and their food plants.

Many people have asked us why we have such an inordinate fascination with fossils, particularly those in amber. The answer is complex but several reasons stand out. Fossils are intriguing because they put human time into perspective. Few of us ever contemplate the primeval past because we live our lives bound to the present, measuring time with clocks and calendars. Fossils remind us of the irrelevancy of our own ephemeral time. How significant is Homo sapiens when our species has only graced this planet for little more than 200,000 years, an infinitesimal blip in the entire chronology of life? The creatures we are studying and writing about existed in the Cretaceous, a spacious interval that began around 145.5 mya (million years ago) and ended about 65.5 mya6 (fig. 1). Just considering the magnitude of that period of time frees us from a rather limited viewpoint of the importance of our own.

Fossils are a rarity delivered to us against overwhelming odds, and that alone makes them spellbinding. To be able to touch the bones of a colossal carnivore that flourished 100 million years ago or peer into the gut of an insect that may have fed on that dinosaur is a privilege. Dinosaurs were around for an astonishing 165 million years. Just how many of them lived and died in that time—trillions? Any figure we come up with is only a guesstimate. While tens of thousands of dinosaur bone and teeth fragments have been found, relatively few articulated dinosaur skele-

Cretaceous Period

Epoch Stage Age (mya)

Figure 1. A geological time scale showing the Cretaceous Period and its associated epochs and stages along with the approximate ages in millions of years ago (mya).6 The dotted bars show the estimated times for the Lebanese (L), Burmese (B), and Canadian (C) amber deposits.

tons have been recovered, and just touching one of these is a gift beyond compare. In 2000, the dinosaur expert Dale Russell7 commented that "although paleontologists have been collecting the remains of Mesozoic animals for more than a century, the total number of known fragments of dinosaur skeletons is only about 5,000". Since then, the number of whole or partial skeletons has certainly increased, but is it any wonder that the auction of "Sue," the skeleton of a T. rex, brought in nearly $8.4 million—a veritable bargain considering.8

While these reasons make working with rare fossils a truly wonderful experience, a great part of their fascination lies in the

Late or Upper

Early or Lower

Maastrichtian

Campanian

Santonian

Coniacian

Turonian

Cenomanian

Albian

Aptian

Barremian

Hauterivian

Valanginian

Berriasian

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