Geotimes Untitled Document Feature
Out of the Past
and Into the Future Douglas H. Erwin Top
paleontology news 2005
Astronomers have observed that our sun lives in a rather boring and uninteresting
part of the galaxy, far from the excitement of the galactic core and lacking even
the interest of a double star. Paleontologists might also view today as a rather
boring and uninteresting interval of geologic history, missing the peculiarities
of widespread continental seas, recent massive continental lava flows or rapid
bursts of evolutionary change. The recent glaciations and the expansion of a group
of highly encephalized primates (us!) aside, the last several million years lack
the drama and peculiarities of the more distant geologic past. But the fossil
record now including a rapidly expanding compendium of traditional fossils,
as well as molecular biomarkers and isotopic measurements provides the
only reliable account of how life has responded to the challenges and opportunities
of past environments.
Paleontology began as a largely descriptive science, using fossils to describe
the diversity of past life, establish correlations and relationships between distant
areas, and help infer the nature of the environment where the fossils were entombed.
By the late 1960s, a new generation of researchers established a fresh intellectual
framework for the field, generally termed paleobiology. The lead in this new enterprise
was taken by Norman Newell of the American Museum of Natural
History, a true giant of the field, who passed away earlier this year.
the greatest recent triumphs of paleontology have come from ... intensive
and rewarding collaborations among paleontologists, stratigraphers, geochemists
Later, Jim Valentine, David Raup and eventually Steve Stanley, Richard Bambach
and the late Jack Sepkoski and Steven Jay Gould, among others, began to ask new
questions about the diversity of life through time: What are the patterns in the
fossil record? How important were mass extinctions in changing patterns of animal
and plant diversity? Are traditional views of evolutionary processes sufficient
to explain the diversity of patterns recorded in the fossil record, or does the
fossil record suggest that new evolutionary processes must have occurred?
Over the past 25 years, research in paleobiology has produced new techniques for
understanding the quality of the fossil record, correcting for preservation differences,
rigorously describing the evolutionary tree of life through phylogenetic analysis,
and generating new means of quantifying changes in form (morphology). Sequence
stratigraphy has been incorporated into paleontological thinking, revealing that
the layered architecture of sediments can have a significant impact on apparent
patterns of fossil abundance.
Among the most encouraging recent developments is a large-scale collaborative
effort, led by John Alroy, Charles Marshall and Arnie Miller, known as the PaleoDatabase
Project. Dozens of paleontologists from around the world have been constructing
a massive record of fossil occurrences to test whether a more rigorous statistical
sampling of the paleontological literature can verify Sepkoskis now accepted
patterns of marine fossil diversity over the past 600 million years, and new results
from this effort can be expected soon. Controversy continues to surround this
project, particularly over how large a trawl of the literature is needed and whether
a literature-based approach is even sufficient, or if a more intensive, field-based
approaches are required. Still, the database project represents a much-needed
step toward a community-wide, geoinformatics approach.
One of the criticisms leveled at such studies of taxonomic diversity, however,
is the lack of sufficient environmental context. Yet some of the greatest recent
triumphs of paleontology have come from just such studies, generally involving
intensive and rewarding collaborations among paleontologists, stratigraphers,
geochemists and geochronologists. The premier example is doubtlessly the study
of the causes and consequences of the end-Cretaceous mass extinction and the generally
accepted demonstration that an extraterrestrial object was responsible for the
event, which led to the demise of the dinosaurs.
In the past few years, the emphasis in extinction research has changed to the
Permian/Triassic mass extinction of 251 million years ago. This year, researchers
further established that this greatest of all mass extinctions occurred in less
than 500,000 years and was evidently closely associated with the eruption of one
of the largest continental flood basalts of the time (see story,
Some of the most exciting research recently has focused on the diversification
of animals that occurred 545 million years ago, called the Cambrian Explosion.
Recent studies of the Cambrian continue to describe new finds but now also include
detailed descriptions of early Cambrian food webs. Paleontologists have also integrated
estimates of the origin of various animal groups based on molecular DNA clocks
with an array of late Precambrian (540 to 800 million years ago) microfossil data
to better understand the new feeding styles, enabled by the origin of the animal
gut and nervous system. Equally important has been trying to understand the relationship
between this extraordinary burst of evolutionary novelty and such environmental
changes as the several late Neoproterozioc glaciations, the end of sulfur-rich
oceans, and an increase in atmospheric oxygen.
Paleontologists, however, have been remiss in developing testable, quantitative,
process-based models of evolutionary and ecological mechanisms on the temporal
and spatial scale for the sort of data we can collect from the fossil record.
The next opportunities for significant advances in paleontology will come from
Critical to this effort will be establishing how to test these process models
using data from the rock record. This sort of approach is already starting to
emerge, and as the techniques spread more widely, they promise to radically restructure
both how paleontologists work and, far more importantly, our understanding of
the history of life.
Erwin is a senior scientist
at the Smithsonian Institutions National Museum of Natural History and a
part-time research professor at the Santa Fe Institute. E-mail: email@example.com.