Dinosaur palaeobiology: a new beginning

It was not until the 1960s and early 1970s that the study of fossils
began to re-emerge as the subject of wider and more general
interest. The catalyst for this re-awakening was a younger
generation of evolutionarily minded scientists eager to demonstrate
that the evidence from the fossil record was far from being a
Darwinian ‘closed book’. The premise that underpinned this
new work was that while evolutionary biologists are obviously
constrained by working with living animals in an essentially
two-dimensional world – they are able to study species, but they do
not witness the emergence of new species – palaeobiologists, by
contrast, work in the third dimension of time. The fossil record
provides sufficient time to allow new species to appear and others to
become extinct. This permits palaeobiologists to pose questions
that bear on the problems of evolution: does the geological
timescale offer an added (or different) perspective on the process of
evolution?; and, is the fossil record sufficiently informative that it
can be teased apart to reveal some evolutionary secrets?
Detailed surveys of the geological record began to demonstrate
rich successions of fossils (particularly shelled marine creatures) –
considerably richer than Charles Darwin could ever have imagined,
given the comparative infancy of palaeontological work in the
middle of the 19th century. Out of this work emerged observations
and theories that would challenge the views of biologists over the
modes of biological evolution over long intervals of geological
time. Sudden massive, worldwide extinction events and periods
of faunal recovery were documented which could not have been
predicted from Darwinian theory. Such events seemed to reset the
evolutionary timetable of life in a virtual instant, and this prompted
some theorists to take a much more ‘episodic’ or ‘contingent’ view
of the history of life on Earth. Large-scale, or macroevolutionary,
changes in global faunal diversity over time seemed to be
demonstrable; these again were not predicted from Darwinian
theory and required explanation.

Most notably, however, Niles Eldredge and Stephen Jay Gould
proposed the theory of ‘punctuated equilibrium’. They suggested
that modern biological versions of evolutionary theory needed to be
expanded, or modified, to accommodate patterns of change seen
repeatedly among species in the fossil record. These consisted of
prolonged periods of stasis (the ‘equilibrium’ period) during which
relatively minor changes in species were observable, and contrasted
with very short periods of rapid change (the ‘punctuation’). These
observations did not fit well with the Darwinian prediction of slow
and progressive change in the appearance of species over time
(dubbed ‘evolutionary gradualism’). These ideas also prompted
palaeobiologists to question the levels at which natural selection
might function: perhaps it could operate above the level of the
individual in some instances?

As a consequence, the whole field of palaeobiology became more
dynamic, questioning, and also outward-looking; it was also
prepared to integrate its work more broadly with other fields of
science. Even highly influential evolutionary biologists such as
John Maynard Smith, who had had little truck with fossils at all,
were prepared to accept that palaeobiology had valuable
contributions to make to the field.
While the general field of scientific palaeobiology was
re-establishing its credentials, the mid-1960s was also a time
of important new dinosaur discoveries; these were destined to
spark ideas that are still important today. The epicentre of this
renaissance was the Peabody Museum at Yale University, the
original workplace of ‘bone-fighter’ Othniel Charles Marsh.
However, this time it was in the person of John Ostrom, a young
professor of palaeontology with a strong interest in dinosaurs.