Empty lot yields trove of ancient plants

Science: Biologists uncover a 90 million-year-old New Jersey landscape.

February 28, 2000|By Carol Kaesuk Yoon | Carol Kaesuk Yoon,New York Times News Service

Ninety million years ago, on what is now an empty lot in Sayreville, N.J., a flower-filled tropical forest stood in flames, its many blossoms burning and smoldering away not into ashy oblivion, but into paleontological perpetuity.

For, as scientists now know, the fires that periodically swept these woods so long ago preserved its blooms as perfect charcoal fossils, creating the most bountiful and exquisitely preserved cache of ancient flowers in the world.

Biologists at Cornell University have uncovered more than 200 species of fossil flowers at the site, including ancient relatives of carnations, cactuses, teas, azaleas, water lilies, oaks, pitcher plants and magnolias. These charcoal flowers, preserved in breathtaking three-dimensional detail down to the level of the individual cell, are revealing not only how ancient relatives of modern plants looked but also, in some cases, how they lived at this time when dinosaurs still roamed New Jersey.

Researchers say the findings are turning botanical lore on its head, by revealing that the great diversification of flowering plants, which are the most species-rich and important group of plants on earth, took place at least 90 million years ago, some 30 million years earlier than previously suspected.

Some of the findings suggest that insects were diversifying along with the plants, providing support for the theory that an interaction between these two groups, which together account for most of the species on earth, may have driven their mutual and explosive diversification.

The site "is a very special place," said David Dilcher, a paleobotanist at the University of Florida, who was not involved in the work. "This is a time when flowering plants were beginning to diversify, caught right in the act. We never realized that until this group started producing the results that they're getting from this locality."

Mark Chase, a molecular biologist at Royal Botanic Gardens at Kew in England, who uses the fossil flowers to date the origins of living plants that he studies, said, "Based on what they're doing we're getting some major changes in our thinking."

But to paleontologists the discovery provides much more than new dates.

William L. Crepet, a paleobiologist at Cornell University, said that finding even one complete fossil flower was "the equivalent of finding a new dinosaur intact."

"It's a fairly amazing thing," he added.

Crepet said there were likely to be billions of charcoal fossil flowers at the site, representing a diversity of species comparable to that of a modern tropical rain forest. Flowers, unlike leaves or pollen, are gold mines of information, often containing all the crucial features needed to identify plants.

Until recently, most paleontologists did not believe flowers were likely to be preserved as fossils. In fact, so unlikely did these finds once seem that paleontologists worked for years on other more standard fossils, impressions left in rocks, at the New Jersey site, without noticing the charcoal flowers that were there.

But there is another good reason earlier researchers missed the flowers: They are tiny, often one-sixteenth of an inch across or less. A tenth to a fiftieth the size of their modern relatives, these nubs must be studied by electron microscope.

"People thought they were just fragments, not very well preserved," said Kevin Nixon, who is on the Cornell team with his wife, Alejandra Gandolfo, and Crepet. "No one really realized what was in there."

The reason for their minuscule size remains something of a mystery. Researchers guess that the reduction in size is due, at least in part, to the process of burning, something Crepet calls "the shrunken-head phenomenon," referring to the way living tissue shrinks when it dries. But researchers note that ancient flowers may also have been much smaller than their modern counterparts to begin with.

While the most stunning finding is the diversity of species, there are particular blossoms whose stories have surprised biologists.

Paleoclusia, for example, is a plant whose modern relatives, the Clusia, produce a sticky resin that is collected by a specialized group of bees, known as meliponine bees. The bees use the resins to defend themselves by globbing the sticky substance, for example, on attacking ants.

They also use it for building nests. To their surprise, researchers found that the tiny Paleoclusia flowers also contained resin canals and had what appeared to be resin residue inside.

"People said: 'How can this be? We have no record of these bees this early,' " said Crepet, creating a paradox of elaborate resin production in the absence of an animal that could use it. But nearby amber deposits have since yielded an unexpectedly ancient meliponine bee of just the right age to be visiting Paleoclusia, suggesting this intimate relationship has been intact for at least 90 million years.

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