one of the arms pokes up out of the webbing to form the cephalopod
version of a penis.
Landman attended graduate school at Yale in the nineteen-seventies.
As a student in the pre-Alvarez days, he was taught that ammonites were
declining throughout the Cretaceous, so their eventual disappearance
was nothing to get too worked up about. “The sense was, oh, you know,
the ammonites were just dying out,” he recalled. Subsequent discoveries,
many of them made by Landman himself, have shown that, on the
contrary, ammonites were doing just fine.
“Here you have lots of species, and we’ve collected thousands of
specimens over the last few years,” he told me over the clank of the
others’ pickaxes. Indeed, in the creek bed, Landman recently came upon
two entirely new species of ammonite. One of these he named, in honor of
a colleague, Discoscaphites minardi. The other he named, in honor of the
place, Discoscaphites jerseyensis. Discoscaphites jerseyensis probably had little
spines poking out of its shell, which, Landman speculates, helped the
animal appear larger and more intimidating than it actually was.
IN their original paper, the Alvarezes proposed that the main cause of
the K-T mass extinction was not the impact itself or even the immediate
aftermath. The truly catastrophic effect of the asteroid—or, to use the
more generic term, bolide—was the dust. In the intervening decades, this
account has been subjected to numerous refinements. (The date of the
impact has also been pushed back—to sixty-six million years ago.) Though
scientists still vigorously argue about many of the details, one version of
the event runs as follows:
The bolide arrived from the southeast, traveling at a low angle relative
to the earth, so that it came in not so much from above as from the side,
like a plane losing altitude. When it slammed into the Yucatán Peninsula,
it was moving at something like forty-five thousand miles per hour, and,
due to its trajectory, North America was particularly hard-hit. A vast
cloud of searing vapor and debris raced over the continent, expanding as