Steven Porter, a Johns Hopkins University senior from
Cherry Hill, N.J., has conducted original research that adds
new and potentially decisive evidence to a debate about the
identity of one of the first organisms to make the epochal
leap from the sea to dry land approximately 400 million
years ago.

As one of 42 Johns Hopkins students who received
Provost’s Undergraduate Research Awards in the 2001-2002
academic year, Porter will present an overview of his
project during an upcoming awards ceremony. It will run from
3 p.m. to 6 p.m. on Thursday, March 7, in the Glass Pavilion
on the Homewood campus, 3400 N. Charles St., in Baltimore.

Although he’s a pre-med student majoring in English, Porter sought out an
undergraduate experience in laboratory research that would
allow him to explore areas beyond his training in molecular
biology and cellular biology. Through a Web site devoted to
undergraduate research opportunities at Johns Hopkins, he
connected with Hope Jahren, an assistant professor in the
Department of Earth and Planetary
Sciences in the university’s Krieger School of Arts and

Jahren’s lab analyzes isotopes of elements like carbon,
nitrogen and oxygen in living and fossilized plants to
better understand their relationship to contemporary and
prehistoric climates. Isotopes are forms of an element that
differ only by the addition of one or more subatomic
particles known as neutrons. Different isotopes of the same
element have different mass, which affects the way plants
use them.

Porter chose to study a unique, high-quality fossil
specimen of Spongiophyton minutissimum from Jahren’s
collection of fossils. Kept in a sealed vial, the specimen
is a little bigger than a dime and dates from the Devonian
Period, a time about 400 million years ago when the seas of
Earth teemed with life but the continents were barren

“Now, look at that morphology [shape],” Jahren asks
when showing the fossil sample to a visitor. “It’s very
tough to get much insight into what type of organism this
was based solely on its shape, but a look at certain aspects
of its chemistry that have been preserved in the fossil may
help give us more clues.”

Whatever it is, Jahren notes, the sample probably
represents a crucial step from life at home only in the sea
to the types of life that could spread over land over the
course of millions of years.

To learn more about the fossil, Porter resolved to
compare it to its nearest modern relatives. But based on
studies of the shapes of various fossil samples of
Spongiophyton minutissimum, paleontologists were
divided into two schools of thought on what those nearest
relatives were. Some thought the fossil was an example of a
bryophyte, a class of plants comprised mostly of mosses; and
some favored the idea that the fossil was a lichen, which is
a close association between a fungus and an alga.

Porter conducted an extensive literature search to
familiarize himself with the debate, and then sought the
advice of experts in the field to further firm up his
understanding. He relishes the fact that he was able to use
his inexperience in the field to get a chance to speak with
prominent people in it.

“My naivete paid off,” Porter says. “I probably would
have been much more intimidated talking to these people,
since they are very much the leaders of their fields.”

Thanks in part to the advice and assistance of people
like Paula DePriest, an associate curator in the department
of botany at the Smithsonian Institution, Porter was able to
select a range of contemporary species of mosses and lichens
to test with the fossil. Using training and equipment from
Jahren’s lab, he looked at the isotopes of carbon found in
each group and in the fossil, and found that the types of
carbon in the fossil more closely resembled those found in
modern lichens.

“It’s very clear from these results that the fossil
cycled carbon in a manner that much more closely resembles
that of the lichens than it does the bryophytes,” Jahren
comments. “Why does that matter? This is one important piece
of how we go from sterile land to what we have today. This
tells us the type of biology that was most effective, at the
very beginning, was the strategy of the lichen, not the

Porter and Jahren hope to present the results at an
upcoming meeting of the Geophysical Society of America. Both
agreed that Porter has come away with valuable insight into
what the process of scientific research is like.

“He’s learned that it’s labor-intensive work, but that
there’s a lasting effect to birthing a new piece of
knowledge,” Jahren says. “I think he also recognizes as a
result of his provost project the amount of luck, in
addition to good planning, that goes into research.”