Zhonghe Zhou talks with
ScienceWatch.com and answers a few questions about
this month's Fast Moving Front in the field of
Multidisciplinary. The author has also sent along
images of their work.
Article: An exceptionally preserved Lower
ZH;Barrett, PM;Hilton, J
Journal: NATURE, 421 (6925): 807-814, FEB 20 2003
Addresses: Chinese Acad Sci, Inst Vertebrate Paleontol
& Paleoanthropol, POB 643, Beijing 100044, Peoples R
Chinese Acad Sci, Inst Vertebrate Paleontol &
Paleoanthropol, Beijing 100044, Peoples R China.
Univ Oxford, Dept Zool, Oxford OX1 3PS, England.
Natl Museums Scotland, Dept Geol & Zool, Edinburgh EH1
1JF, Midlothian, Scotland.
Why do you think your paper is highly
The article is highly cited largely because there is such widespread
interest in the exciting discoveries of exceptional fossils that have been
made in the lacustrine Lower Cretaceous deposits of northeastern China.
These finds have contributed significantly to shaping our views on the
evolution of a number of important groups of animals and plants in the
Mesozoic, such as feathered dinosaurs, early birds, mammals, and flowering
plants. The paper provided a comprehensive summary of the discoveries that
had been made up to 2003, and their evolutionary implications.
The paper also gave an account of the geological background to the fossil
finds, discussing such matters as the age of the deposits, the tectonic,
paleogeographical, and paleoenvironmental setting in which the biota lived
and evolved, and their exceptional preservation. Thus, it represented the
first effort to understand these discoveries from a paleoecological
perspective. In addition, the paper presented some original ideas such as
the "cradle hypothesis," an explanation for the composition of the Jehol
Biota, and basically dismissed the alternative "refugium of relics"
Finally, recent discoveries and studies have made research on the Jehol
Biota into one of the fastest growing areas in paleontology, and one that
has attracted not only paleontologists but also evolutionary biologists and
geologists on a global scale.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
The paper did not describe any newly discovered fossils. Rather, it
presented a synthesis of extraordinary discoveries, mainly from the Early
Cretaceous age of China, that have greatly increased our knowledge of the
evolution of many biological groups such as birds, dinosaurs, mammals, and
angiosperms. The paper also summarized what were then recent breakthroughs
in the dating of the fossil-bearing deposits, an issue that was at one time
Although no new methods were introduced in this paper, we did adopt a
multidisciplinary approach that integrated many different aspects of what
might be called Jehol studies. Bringing disparate lines of evidence
together opened a new window on this terrestrial Early Cretaceous
Would you summarize the significance of your paper
in layman's terms?
In this paper, we argued that the Jehol Biota provided significant fossil
evidence supporting both the hypothesis that birds evolved from among
dinosaurs and the hypothesis that flight evolved "from the trees
down"—in an arboreal environment, rather than a terrestrial one.
Among the Jehol fossils, the most significant are probably the feathered
dinosaurs, which are generally small and have a very close phylogenetic
relationship with birds.
We also discussed the significance of the associated early birds and
mammals, and their implications for understanding the evolutionary history
of these groups in the Cretaceous. Similarly, we explained how plants from
the Jehol bridge chronological and evolutionary gaps between other Mesozoic
plants and the modern flora.
We concluded that the Jehol Biota indisputably belongs to the Early
Cretaceous rather than the Late Jurassic, being approximately 120-125
million years old. The most unequivocal evidence for this comes from direct
dating of the ashes interbedded with the fossil-bearing sediments.
Based on these relatively solid radiometric dates, on biostratigraphic
correlations of the Jehol fossils with those from other regions, and on
Cretaceous paleogeography, we proposed that the Jehol Biota was an
evolutionary "cradle" in which many major groups originated and
We further suggested that the Jehol Group could be viewed as a window on an
interesting case of faunal succession in an Early Cretaceous terrestrial
biome, in which an established biota merged with and was partially replaced
by a novel biota composed of both immigrants and new taxa that were
evolving in situ.
How did you become involved in this research and
were there any particular problems encountered along the way?
I first got involved in the study of the Early Cretaceous vertebrates from
the Jehol Biota in Liaoning in 1988, when I was working on my master's
thesis on a fossil fish. Extraordinary discoveries began to be reported
from this region in the early 1990s, including early birds, feathered
dinosaurs, pterosaurs, amphibians, primitive mammals, flowering plants,
insects, and others. These finds have of course drawn enormous attention
from among both scientists and the general public.
Since the 1990s my focus has been on the study of early birds. I have also
become involved in studies on feathered dinosaurs and pterosaurs, as well
as the stratigraphy of the fossil-bearing sediments. These diverse projects
have helped me to acquire a more comprehensive understanding of the Jehol
"the paper presented some original
ideas such as the "cradle hypothesis," an
explanation for the composition of the Jehol
Biota, and basically dismissed the
alternative "refugium of relics" hypothesis.
In late 2001, I was invited to write a review article for Nature
on the Jehol Biota together with Paul Barrett, a dinosaur expert at the
National History Museum of London, and the paleobotanist Jason Hilton, a
Senior Lecturer in Palaeobiology at the University of Birmingham. The 2003
paper was the result of that invitation. I did not encounter any particular
problems while we were working together on this research, and in fact my
colleagues' expertise on dinosaurs, plants, and paleogeography dovetailed
nicely with my own research interests. It was a collaborative project in
the best and most satisfying sense of the term.
Where do you see your research leading in the
Study of the Early Cretaceous Jehol Biota is entering a new era. Many Jehol
taxa have already been named and described. Exciting discoveries are still
being made, and are rounding out our understanding of the biodiversity of
this Lower Cretaceous terrestrial ecosystem. However, we are now reaching a
stage where we can revisit some of the previously described species and
evaluate them in more detail, in order to learn more about their
implications for the evolution of Cretaceous vertebrates in general.
The transition from non-avian theropods to birds is a good example. In
recent studies dealing with this transition, attention has shifted to
tracing the complex distribution of characters and character
transformations among advanced theropods. New pieces of evidence in support
of both the terrestrial and the arboreal hypotheses for the origin of bird
flight have been revealed, and this is probably telling us that the
evolution of flight was a complex process possibly incorporating elements
of both scenarios.
The idea of a simple dichotomy between the terrestrial and arboreal
alternatives is looking increasingly outdated, and the new focus should be
on reconstructing the detailed anatomical and functional changes that took
place at each stage of a continuous transition from flightless theropods to
Paleoenvironmental studies hold the key to a successful reconstruction of
the paleoecosystem. A more complete geochronological and paleomagnetic
framework is essential for understanding the relationship between the
evolution of the Jehol Biota and its paleoenvironmental context. More
reliable and extensive biostratigraphic correlations between the Jehol
Biota from northeastern China and its counterparts in other regions can
provide more information on the origins and radiations of major biological
The interactions among various groups of animals and plants represent
another important topic that merits further discussion. Geochemistry is
expected to play a key role in interpreting the actual paleoenvironments
that the biota inhabited.
Finally, it is well known that the Early Cretaceous was a time of frequent
volcanism and strong tectonic activity, as well as a global warming trend
that reached its climax in the middle of the Cretaceous. The relationship
between the origin and evolution of the Jehol Biota and these major global
and regional geological events needs careful investigation, and the Jehol
has the potential to be a central case study for the effect of geological
and climatic events on Cretaceous ecosystems.
Do you foresee any social or political implications
for your research?
Unfortunately, I do not think this research has any remarkable social and
political implications. The paper by Zhou et al. (2003) did touch
on collection strategies and some associated problems, which probably has
led to more international awareness of the widespread illegal collecting,
fakery, and smuggling that plague Chinese paleontology. However, raising
awareness is not the same thing as finding solutions to these problems,
which of course was well beyond the scope of the research. I think the
paper did show how critical new fossil evidence can demonstrate the
tremendous explanatory power of evolutionary theory, which is,
unfortunately, often challenged by creationists even today.
Zhonghe Zhou, Ph.D.
Senior research fellow and acting director
Institute of Vertebrate Paleontology and Paleoanthropology
Chinese Academy of Sciences
Keywords: lacustrine lower cretaceous deposits,
northeastern china, evolution, mesozoic, feathered dinosaurs, early birds,
mammals, flowering plants, evolutionary implications, tectonic,
paleogeographical, paleoenvironmental setting, jehol biota,
paleontologists, evolutionary biologists, geologists, early cretaceous age
of china, dating of fossil-bearing deposits, cretaceous paleogeography,