Travel Reference
In-Depth Information
symbiotic, single-celled phytoplankton in their flesh, which aid in respira-
tion and shell formation. Many scientists thought that the inoceramids used
the same
trick, or perhaps
they
used bacteria
instead.
"We shall
see,"
he told
himself.
He took a small sample of the sediment and then placed an entire in-
oceramid, shell and all, in the large pouch sewn into his buoyancy compen-
sator. With these samples packed away, he shoved off the bottom, taking
photos with his camera as he rose, thinking of the papers that would he writ-
ten about these clams and thinking of other things: his air supply, the depth,
the time, and the other animals he needed to find.
The dive was a great mix of the unknown and the familiar. The sandy
bottom was like many he had seen before, in his own time. The fields of clam
necks, the tropical mollusks and echinoderms—much of what he saw had a
perfectly modern appearance. But othet things, such as the inoceramids and
the partly buried trigoniid clams, were foreign—anomalies that were jarring
to his trained eye. They were so out of context. They should be fossils in an
outcrop, not loosely scattered on this bottom, not so obviously alive.
He powered on, his large fins and steady kick carrying him rapidly over
fertile fields of the clam-rich community. He decided to descend furthet and
began to follow the sloping bottom into deeper water, looking for those crea-
tures he had so long dreamed about and so long studied, the Mesozoic swim-
ming shellfish called ammonites.
He knew what they ought to look like. Some had shells like great
wagon wheels with the body of a squid stuffed inside
("Perhaps*."
he told him-
self) or, more probably, like that of the chambered nautilus of his own time,
the last remaining member of the long-lived group of now largely extinct
cephalopods to which the ammonites belonged. Others had evolved more
ambiguous shapes—some straight, some like snails, some like candy canes,
some like the mess a child makes with a capless tube of toothpaste—and no
scientist knew what these uncoiled forms did for a living or even how or
where in the ocean they lived. About the mystetious ammonites only one
thing was certain: All of them, irrespective of shape, died out in the same
great catastrophe that killed the dinosaurs, a calamity brought about by the
