The Fate of the Method of ‘Paradigms’ in Paleobiology
Journal of the History of Biology
The Fate of the Method of 'Paradigms' in Paleobiology
MARTIN J. S. RUDWICK 0
0 Department of History and Philosophy of Science University of Cambridge Cambridge UK
An earlier article described the mid-twentieth century origins of the method of ''paradigms'' in paleobiology, as a way of making testable hypotheses about the functional morphology of extinct organisms. The present article describes the use of ''paradigms'' through the 1970s and, briefly, to the end of the century. After I had proposed the paradigm method to help interpret the ecological history of brachiopods, my students developed it in relation to that and other invertebrate phyla, notably in Euan Clarkson's analysis of vision in trilobites. David Raup's computer-aided ''theoretical morphology'' was then combined with my functional or adaptive emphasis, in Adolf Seilacher's tripartite ''constructional morphology.'' Stephen Jay Gould, who had strongly endorsed the method, later switched to criticizing the ''adaptationist program'' he claimed it embodied. Although the explicit use of paradigms in paleobiology had declined by the end of the century, the method was tacitly subsumed into functional morphology as ''biomechanics.''
Paleobiology; Functional morphology; Paradigm; Stephen Jay Gould; David Raup; Adolf Seilacher; Martin Rudwick
A previous article (Rudwick, 2017) summarized the history of research
in the early to mid-twentieth century on the functional morphology of
extinct organisms, in relation to the concept of Pala¨obiologie. This kind
of paleontology was developed, initially in the German-speaking world,
in contrast to the dominant worldwide practice of paleontology as a
science centred on taxonomy and oriented primarily towards serving the
needs of stratigraphical geology. Within ‘‘paleobiology’’ my article
focused on the kind of functional inference that I proposed in 1961 as the
method of ‘‘paradigms,’’ adopting this then unusual word just 1 year
before Thomas Kuhn (
) famously gave it much wider currency with
a quite different meaning. The article summarized a few of the ‘‘worked
exemplars’’ that I published during the 1960s to illustrate the paradigm
method in action, and to argue that it enabled rival functional
interpretations of specific morphological features – and hence of the whole
‘‘ways of life’’ of extinct organisms – to be tested for their relative
plausibility (e.g., Rudwick, 1961, 1964a, 1965). These case-studies were
all drawn from the fossil record of brachiopods, a major phylum for
invertebrate paleontologists although often dismissed as ‘‘minor’’ by
those biologists who only study living organisms. However, in
explaining the paradigm method to philosophers of science I had argued
that it had epistemological implications for functional inferences on
fossil organisms of all kinds, and that it was therefore relevant to the
interpretation of the history of life as a whole (Rudwick, 1964b).
The present article continues this narrative account of the method of
paradigms in paleobiology through the 1970s and beyond, in the wider
contexts of functional morphology and the evolutionary interpretation
of the fossil record. I shall describe how, and suggest why, the method
met with such a mixed reception, ranging from enthusiastic adoption
through indifference to outright rejection. I shall trace its ambivalent
fate in paleobiological practice, and outline its role in the history of
evolutionary theorizing in the late twentieth century.
The history of the paradigm concept in paleontology illustrates the
diversity of the factors that may impinge on this kind of scientific
research. These ranged from the material and interpersonal, such as the
access that particular scientists were given or not given to specific
collections of fossil specimens, to the most abstractly conceptual, such as
the unspoken fear that any use of the language of ‘‘organic design’’ in
biology (or paleobiology) might open the door to some variety of deistic
metaphysics or even to ‘‘intelligent design’’ creationism.
I myself (Martin Rudwick 1932–) ceased after 1971 to contribute
directly to this paleontological research, having in 1967 moved my main
field of teaching and research into the history of the sciences that until
then I had been practicing professionally. In the present article the
autobiographical element is therefore less pronounced than in the
previous one; but I will repeat here that it is not my intention to use these
articles to rehabilitate, vindicate or celebrate my own earlier research.
My aim is simply to use the evidence of my publications and those of
other paleontologists, supplemented by a few unpublished sources and
my personal recollections, to reconstruct a significant phase in the
twentieth-century history of the science of evolutionary paleontology.
The focus here is, without apology, on work that was directly or
indirectly related to my own and my students’ contributions to this research;
but I hope this article may be useful as a primary source for any
historians (or paleontologists) who want to explore the history of this kind
of science more extensively and in greater depth than has been feasible
here. Certainly the history of paleontology in the twentieth century is a
field of research that deserves much greater scholarly attention.
Paradigms and the History of Life
My earlier research on fossils was focused, as just mentioned, on
developing a method by which rival functional interpretations of specific
morphological features of extinct organisms could be tested, with the
hope of undercutting the then common criticism that functional
interpretations of fossils were intrinsically speculative and therefore almost
worthless. But my intention from the start was that any such
interpretations should contribute to the reconstruction of the ‘‘ways of life’’ of
whole organisms, and hence to the interpretation of the adaptive
evolution of the groups to which they had belonged. Following this policy,
my later research, much of it carried out jointly with my former student
Richard Cowen (1940–), had embedded our functional reconstructions
of specific brachiopods within the evolutionary history of the whole
phylum (as summarized in Rudwick, 1970), suggesting for example their
implications for contentious issues such as adaptive radiations, parallel
evolution, convergence, and mass extinctions.
The last of these was particularly controversial at this time (more
than a decade before the headlines were hit by the melodramatic claim
that an asteroid might have hit the Earth and wiped out the dinosaurs).
Any suggestion of mass extinctions was widely rejected as a throwback
to an outworn and unscientific ‘‘catastrophism,’’ and the alleged
evidence for such events was dismissed as the product of a highly imperfect
fossil record. Nevertheless, Cowen and I, and just a few of our elders
and betters, were particularly impressed by the magnitude of the
apparent mass extinction at or around the end of the Permian period
(and of the Paleozoic era). More specifically, we noted how it seemed to
have eliminated some of the most intriguing and perhaps most
‘‘promising’’ innovations ever developed by brachiopods in the course
of their evolution. Of these, the peculiar morphology of Prorichthofenia,
serving a putatively unusual feeding mechanism (Rudwick, 1961), might
have been just one. Others were suggested by the equally aberrant
morphologies of some other Permian brachiopods known from many
localities scattered around the world. The abundant and exceptionally
well-preserved specimens from Texas, a few of which I had been able to
use for my study of Prorichthofenia, were being prepared for publication
by G. Arthur Cooper (
) and Richard Grant (
Washington D.C., and were not readily available to other
paleontologists. Alternative sources were, for example, specimens from the Salt
Range in Pakistan or, more accessibly, those collected since the late
nineteenth century in the Sosio valley in Sicily. Our own fieldwork in
Sicily in 1966 yielded few new specimens, but the Italian university
museums in which earlier finds had been deposited provided plenty of
quite well-preserved material for our review of several aberrant
brachiopod genera, and for our functional interpretations of
correspondingly aberrant modes of life.
In particular, the Sosio specimens seemed to confirm my earlier
interpretation of Prorichthofenia and related ‘‘richthofeniids’’ from
Texas: namely, that a vigorous ‘‘flapping’’ action without parallel
among living brachiopods, though somewhat analogous to the pumping
action of living septibranch molluscs, could have brought them unusual
kinds of floating food (Rudwick, 1961). The Sicilian fossils also became
the basis for our interpretation of the quite different – but equally
peculiar – morphology of Lyttonia (the broad generic name given at the
time) and related ‘‘lyttoniids.’’ In these aberrant brachiopods, as in
richthofeniids, the shelly ventral valve is hollow or even conical, and a
very thin dorsal valve is recessed within it. But the lyttoniid dorsal valve,
unlike the trapdoor-like dorsal valve of richthofeniids, is large and
complex, being deeply divided into many lateral lobes separated by
narrow slits. The British paleontologist Alwyn Williams (
had inferred, by analogy with some living brachiopods, that the
‘‘lophophore’’ or suspension-feeding organ of lyttoniids was of
multilobed or ‘‘ptycholophe’’ form, with its very long axis running all around
the edges of these shelly lobes (Williams, 1953). Cowen and I developed
this into a functional reconstruction of a possible ‘‘rhythmic-flow’’
mechanism partially analogous to that attributed to richthofeniids; or,
less conjecturally, perhaps a ‘‘steady-flow’’ filtering mechanism broadly
comparable to the suspension-feeding operated by all living
brachiopods as well as by many other unrelated organisms such as bivalve
molluscs and ascidians (Figure 1).
These and several other peculiar Sosio brachiopods were analysed
functionally in a densely illustrated monograph that we published in a
leading Italian paleontological journal (Rudwick and Cowen, 1968). We
also included some comments on the environmental and climatic
implications of what we interpreted as a possibly tropical reef
environment. But such questions of paleoecology, paleoclimatology and
paleogeography were touched on only briefly, because at this time the
underlying issues of continental mobilism (commonly but misleadingly
called ‘‘drift’’) and plate tectonics were still unsettled and highly
controversial among geologists and geophysicists. Indeed the specific case
of the worldwide Permian marine faunas, including prominently their
aberrant brachiopods, had recently been reviewed with almost no
reference to the possibility of radically changed latitudes or continental
positions (Stehli, 1964). On the other hand Cowen and I did refer to the
opinion – then equally common among paleontologists – that in reality
there had not been any mass extinction event around the end of the
Permian period, and that any appearance to the contrary was merely
due to the imperfection of the fossil record. Noting the aberrant but
‘‘promising’’ features of many of the highly diverse Sosio brachiopods,
we commented that ‘‘Such innovations as these might have been
expected to lead to new phases of adaptive radiation, but instead they
were all eliminated,’’ and, by geological standards, suddenly. As we
concluded somewhat tartly, ‘‘This requires to be explained, and not
merely explained away’’ (Rudwick and Cowen, 1968, p. 172).
Around the same time I tried to put the strange Permian lyttoniids
into a wider evolutionary context, by analyzing the small lyttoniid
Poikilosakos of Pennsylvanian (late Carboniferous) age. This had long
been regarded as the likely ancestor of all the later and more elaborate
Permian forms. I interpreted it in a way that connected it functionally
both to them and to its own likely ancestors among still earlier and less
aberrant brachiopods (Rudwick, 1971). This paper, which was my last
contribution to paleobiology, was eventually published in the
Festschrift that honored Cooper’s long and distinguished career as a
paleontologist (Dutro, 1971). Cooper had been politely sceptical about
my functional interpretations of his beloved brachiopods, but his
taxonomic work had been massive in its impact. In 1969 he and Grant
published a foretaste of their detailed taxonomic research on the
Permian brachiopods from the Glass Mountains (Cooper and Grant,
1969), in the first issue of their institution’s significantly titled new
journal Smithsonian Contributions to Paleobiology. Yet they made few
functional comments on their many newly described and newly named
genera and species, and did not mention my interpretation of the
richthofeniids even to refute it. Cooper’s attitude towards the concept of
‘‘paleobiology,’’ and that of many other American paleontologists of his
generation, remained both ambiguous and ambivalent.
Paleoecology and Functional Morphology
The method of paradigms was of course an application, within
paleontology, of the well established biological tradition of functional
morphology, which in turn was related to the broader field of ecology.
These were aspects of biological science that in the 1960s were being
applied with renewed vigor to fossil organisms: not only in the German
cultural region that before the Second World War had seen the lively
practice of ‘‘Pala¨obiologie,’’ but also in the ‘‘paleobiology’’ championed
during the postwar years by George Simpson (
) and Norman
) in New York (see Sepkoski, 2012, pp. 54–67). James
Beerbower’s Search for the Past (1960), for example, was a sign of this
significant change in the science in America: its author was primarily a
zoologist, and in contrast to earlier textbooks of palaeontology his work
devoted much of its space to interpreting how fossil organisms might
have lived. And it was soon followed by the British palaeontologist
Derek Ager’s Principles of Paleoecology (1963), subtitled ‘‘the study of
how and where animals and plants lived in the past.’’ However, as
Ager’s book showed, much paleoecological work was concerned with
reconstructing the environments of the past and the assemblages of
organisms that had characterised them (‘‘paleosynecology’’) rather than
with the functional interpretation of the morphologies and adaptations
of individual organisms (‘‘paleoautecology’’). For example, Ager himself
described in a separate paper ‘‘The adaptations of Mesozoic
brachiopods to different environments,’’ as represented by those preserved
in stratigraphical formations of different facies (Ager, 1965); but he did
not take the further step of interpreting their varied morphologies in
terms of distinctive functions or adaptations. Significantly, this paper
was published in the first volume of Palaeogeography Palaeoclimatology
Palaeoecology: the cumbersome but informative title of this new journal
signaled the recognition of a distinctive cluster of related research
problems. It soon became an important outlet for research with global
dimensions, as for example in the major study by the British
paleontologist Anthony Hallam (1933–) on ‘‘The bearing of certain
palaeozoogeographic data on continental drift’’ (Hallam, 1967).
Studies of invertebrate fossils in terms of functional morphology
belonged in a more specifically biological cluster of problems. Such
studies were of course far from being limited at this time to my studies
of brachiopods. For example, Klaus-Peter Vogel (1931–) of Tu¨ bingen –
working, significantly, in the German environment of Pala¨obiologie –
had interpreted the morphology of the highly aberrant Mesozoic
‘‘rudist’’ molluscs in terms of their ‘‘Struktur und Funktion’’ (Vogel,
1960). Vogel later used my account of suspension-feeding in living
brachiopods (Rudwick, 1962) as the homological and analogical key to
interpret in functional terms the morphology of some distinctive fossil
forms, though without explicit reference to the idea of paradigms. He
interpreted the bizarre ‘‘key-hole’’ in the shell of the Jurassic brachiopod
Pygope as an efficient outlet for an exhalant water current directed well
clear of the inhalant ones, in an exceptionally calm deep-water
environment (Vogel, 1966). And Grant, while working with Cooper on the
spectacular Permian brachiopods from Texas, offered functional
interpretations of various ‘‘productide’’ brachiopods: he suggested that their
external shelly spines were diversely adaptive devices, serving in some
forms to anchor the shells to the stems of crinoids clear of a soft
substrate, or, in others, to make possible an almost infaunal habit by
stabilising the shells within a similar muddy substrate (Grant, 1963, 1966,
During the same years, other paleontologists were exploring similar
kinds of interpretation for fossils of quite different phyla. For example
the British paleontologist Christopher Paul (1941–), who like Cowen
had begun his research at Cambridge, was working on cystoids, an
enigmatic and totally extinct group of Paleozoic echinoderms. He
published fine studies of the ‘‘functional morphology and mode of life’’
of one particular genus (Paul, 1967), and of the ‘‘morphology and
function’’ of some distinctive features of the group (Paul, 1968, 1972).
Citing the paradigm method, he noted that these features
(‘‘porestructures’’) ‘‘agree closely with the paradigm of an exchange system’’
and were therefore likely to have been respiratory in function; and that
they had evolved ‘‘from less to more efficient types,’’ as judged by their
progressive approximation to a paradigm that was ‘‘assumed to have
maximal efficiency within the limits imposed by the materials of which
the fossil structure is made’’ (Paul, 1968, pp. 706–707). This expressed
very well the essence of the paradigm method as I had conceived it.
However, the ambivalent or optional role of the paradigm method in
the functional interpretation of fossils is illustrated by what was being
done by my own graduate students at Cambridge during the 1960s.
Cowen, who had become my close collaborator on our research project
on the functional evolution of the whole brachiopod phylum, used it
effectively though tacitly in his own studies of brachiopod morphology,
as well as collaborating with me in our functional interpretations of
some of the highly aberrant Permian forms. I encouraged two other
students to explore, like Paul, the functional interpretation of
invertebrate fossils of other phyla. Robert Carter (
) worked on
bivalve molluscs, which in some important features – for example the
bivalved shell growing by accretion at the mantle edges – were obviously
analogous to brachiopods. In particular, he analysed the morphology of
certain fossil oysters (Arctostrea) of Cretaceous age, which during
ontogeny had developed strongly zigzag valve edges (Carter, 1968). These
zigzags were strikingly similar to those in brachiopods that I had
interpreted as protective in function (Rudwick, 1964a), but they were on
shells of quite different form. Carter cited my paper and used the terms
‘‘paradigm’’ and ‘‘paradigmatic’’ frequently though without special
explanation. But he did not adopt the strictly geometrical analysis that I
had used to measure the degree of approximation between my
brachiopods’ zigzags and those I claimed would be ‘‘paradigmatic’’ for
ensuring a uniformly narrow slit (which could have functioned
efficiently as a protective device). Instead of adopting that interpretation,
Carter argued that his oysters’ zigzags were an adaptation that had
improved the flow of water in and out of the mantle cavity and on to the
gills. I thought this explanation less satisfactory, because it did not
exploit the paradigm method’s potential for testing alternative
functional explanations against one another. (Carter later moved his
research into more conventional paleoecology and stratigraphy; late in life
he became famous – or notorious – in Australia as a prominent ‘‘climate
Of all the research by my students at this time, what gained the most
attention among other palaeontologists was that published by Euan
Clarkson (1937–) on the eyes of trilobites. Developing an initial
suggestion of mine, Clarkson constructed a device for plotting the precise
orientations of the relatively large individual lenses in the ‘‘schizochroal’’
compound eyes of some well-preserved trilobites (phacopids and
acastids) of Silurian age. He then reconstructed the fields of view that the
animals would have had (all round, but usually narrowly horizontal),
with a precision and certainty that was derived directly from the
threedimensional geometry of their eyes. And from this he inferred the likely
function of the eyes – for detecting other benthonic animals, primarily
for defense – and the trilobites’ general modes of life (Clarkson, 1966a,
b). He cited my paper (Rudwick, 1964b) for ‘‘the methodology of such
functional interpretation[s] of fossil structure,’’ but did not refer
explicitly to the idea of paradigms. Nonetheless, his study of trilobite
eyes was a superb example of a close approximation between observed
structures and those that were clearly paradigmatic for the inferred
function of all-round benthonic vision (Figures 2, 3). And while he had
no reason or need to refer back to the early history of his science, it is
relevant in the present context to note that the all-round vision made
possible by many trilobite eyes had already been commented on – with
evident astonishment at their superb ‘‘organic design’’ – by Georges
Cuvier’s younger contemporary and admirer William Buckland, during
the great pre-Darwinian flowering of fossil functional morphology in
the early nineteenth century (see Rudwick, 2008, pp. 434–435).
From this summary of some of my own students’ work it is clear that
an explicit use of the paradigm method was not a necessary condition
for their functional interpretations of fossil morphologies. Yet my own
strong commitment to it may have encouraged them to share my
working assumption that any and every fossil structure may have been
adapted more or less effectively to some specific function (or to some
combination of functions or to some compromise between them), so
that it would always be worthwhile to try to investigate what these
adaptations might have been. Unless one was on the lookout for
possible adaptations one would never detect them. To put it more strongly,
adaptedness deserved to be a working assumption in any morphological
research on fossils; it was unwise, and methodologically unjustified, to
set a priori any limits to the functional optimizations that natural
selection might have generated in the course of evolution. Conversely,
as I had argued (Rudwick, 1964b), it was logically impossible to prove
that any fossil structure had had no adaptive advantage, whatever one’s
view of the power of natural selection.
A fine example of the fruitfulness of this kind of approach, owing
nothing (as far as I know) to my work, came from the young American
paleontologist Steven Stanley (1941–), whose research at Yale – one of
the leading centers for paleontology in the United States at this time –
interpreted a major feature of the evolutionary history of bivalve
molluscs in terms of a crucial morphological innovation (Stanley, 1968). As
with Nichols’s impressive earlier study of the micro-evolution of the
Cretaceous sea-urchin Micraster (Nichols, 1959a, b), Stanley’s work did
not need the kind of rather abstract analysis represented by the
paradigm method, because the functional morphology of his fossils could be
interpreted with some confidence in the light of substantial knowledge
of their living relatives. Stanley interpreted the greatly enlarged
representation of bivalves among post-Paleozoic marine fossils as the record
of a major adaptive radiation, which was made possible by the
evolution, in certain bivalves, of a partial fusion of the mantle edges. This
enhanced these bivalves’ suspension-feeding systems by enabling the
inhalant and exhalant apertures and water currents to be separated
more effectively. But in time it also made possible the further evolution
of the fused mantle edges into tubular ‘‘siphons,’’ which eventually
allowed many of these molluscs to adopt and exploit deeply infaunal
modes of life that had not previously been accessible to any bivalve
molluscs. Stanley argued that this gave them a major new adaptive
advantage: after the apparent crisis at the end of the Paleozoic era (the
possible mass extinction at the end of the Permian period), bivalves had
not only replaced vanished kinds of brachiopods in many marine
environments, but they had been able to go much further in exploiting
many more diverse environments than before.
Theoretical Morphology and Its Functional Implications
Stanley’s research was symptomatic of a growing trend towards
integrating studies of living and fossil invertebrates in interpretations of
functional morphology, not only for specific organisms but also for the
evolutionary histories of the larger groups to which they belonged. My
own attempted synthesis of the adaptive evolution of brachiopods,
published shortly afterwards and summarizing my joint research with
Cowen, was another case in point (Rudwick, 1970). All this functional
morphology was, knowingly or not, following in the tradition of earlier
research in the nineteenth century, as analyzed in E. S. Russell’s classic
Form and Function (1916). A related but initially distinct kind of
research was inspired by D’Arcy Thompson’s equally classic On Growth
and Form (1917; 2nd ed. 1942), which had focused attention on the
ontogenetic development of morphology, and hence also on its
phylogenetic history. Here a sensational new note was struck in the 1960s by
the American paleontologist David Raup (
), then at Johns
Hopkins. Raup’s spectacular images of ‘‘hypothetical snail forms’’
(Raup, 1962; Raup and Michelson, 1965) – first published in Science
and therefore gaining wide attention – were derived from Thompson’s
analysis of the geometry of ‘‘logarithmic’’ or ‘‘equiangular’’ spiral forms
in diverse organisms (Thompson, 1917, pp. 493–586; 1942, pp. 748–
849); but Raup’s were generated by early computers, both analog and
digital, which of course had not been available to Thompson or his
contemporaries (Figure 4).
Raup developed this work into a concept of ‘‘theoretical
morphology’’: he used his computers to generate a matrix of all the shapes
theoretically ‘‘possible in this universe of ours’’ – though he did not use
Pantin’s (1951) memorable phrase – by varying the basic parameters in
the relative rates of accretion at the growing edges of shells. Within this
theoretical ‘‘morphospace’’ (as it was later called) he plotted the much
more restricted distribution of shapes that had in fact ever developed in
the course of the evolution of shells formed by accretionary growth
(particularly those of gastropods and cephalopods, but also bivalves
and brachiopods). This had obvious functional implications, since many
theoretically possible shapes might never have evolved, or only rarely,
simply because they were biologically unviable or intrinsically
illadapted. Raup’s further work on these lines was published among the
predominantly taxonomic and stratigraphical papers in the Journal of
Paleontology (Raup, 1966, 1967), signaling a belated broadening of the
scope of this leading journal in a paleobiological direction (Stanley’s
1968 paper was also published there).
It was thus a sign of the times that Raup proposed a symposium on
‘‘Paleobiological aspects of growth and development,’’ which was held
in New Orleans in 1967 during the annual meeting of the Geological
Society of America (Macurda, 1968). The use of the word
‘‘paleobiological’’ in this context was still quite unusual in the anglophone world;
and its institutional setting, at least for invertebrates, remained
markedly geological rather than biological. At this meeting Raup himself
tackled a much more complex case than his snail shells, namely that of
the accretionary growth of the mosaic of shelly plates that makes up the
shell of a sea-urchin: he harnessed the power of his computers to
reconstruct ‘‘the ontogeny of the entire plate pattern’’ (Raup, 1968).
This was ‘‘theoretical morphology’’ at its most refined: geometrical
analogies with soap bubbles and the cells of honeycombs were
prominent in Raup’s reasoning; the varied functions of the plates in the life of
sea-urchins were not (though of course he was well aware of the
Another American paleobiologist who contributed to this
symposium was Stephen Jay Gould (
), who had just moved to
Harvard after studying with Newell at Columbia. Gould was far from
being the public celebrity he later became. But he had recently – while
still a graduate student – made a striking scientific debut with a major
essay on ‘‘Allometry and size in ontogeny and phylogeny’’ (Gould,
1966), published, with the support of the distinguished evolutionary
theorist Julian Huxley (
), in the prestigious Cambridge
journal Biological Reviews. Like Raup’s work, Gould’s was marked by
an accent on quantitative issues and mathematical methods, which
became the hallmark of all their later research. At New Orleans Gould
used some of his doctoral research on fossil snails from Bermuda to
present an allometric analysis of ‘‘Ontogeny and the explanation of
form.’’ He also used his analysis of ontogeny to indicate, at least briefly,
the possible implications of growth and form for functional
morphology: among his suggested explanations of evolutionary parallelism were
the cases where ‘‘the adaptation arises many times because it is the only
possible solution to a given [functional] problem’’ (Gould, 1968, p. 97).
At Raup’s suggestion I too was invited to contribute to this
symposium; I was the only speaker from outside the United States. It was at
New Orleans that I first met Raup and Gould: although I had spent
several summer periods in Washington in the preceding years, studying
fossil brachiopods in the U.S. National Museum, I had not previously
met any of the younger American scientists who were working in
strongly paleobiological directions like my own. I used the occasion to
develop my earlier brief analysis of the growth and form of brachiopod
shells (Rudwick, 1959), but also to integrate it with a further
explanation of my method of paradigms (Rudwick, 1964b), covering the
functional analysis of the ontogenetic development of brachiopods, and
hence also of their likely phylogenies (Rudwick, 1968). While my work
was primarily qualitative, I did use the example of lyttoniid morphology
to suggest how the growth of the bizarre and strangely variable dorsal
valve had been governed during both ontogeny and phylogeny by
simple morphogenetic rules; I illustrated this with manually-generated
hypothetical forms that replicated real specimens, while recognizing that
in principle they, like Raup’s, could have been produced by an
appropriate computer program, had I been competent to do so. In any case
the forms of the dorsal valve could be related to its function in the
putative feeding mechanism (Figure 5).
Before publication my paper was sent to be assessed by Grant,
Cooper’s collaborator and, as already mentioned, the author of papers
on the functional interpretation of specific features of some Permian
brachiopods; he might have been expected to be more sympathetic than
his senior colleague towards such work. But Grant disliked what he
regarded as my ‘‘polemical style’’: I had indeed been critical of the
failure of most brachiopod specialists to take the implications of
accretionary growth, let alone any functional issues, into account in
their descriptive and taxonomic work. More seriously, however, while
Grant conceded that the paradigm method ‘‘has produced some
extremely interesting and stimulating results,’’ he dismissed it as no more
than commonsense, ‘‘with the highly convoluted terminology of
‘paradigmatic functional analysis’’ added later as an ‘‘encrustation’’’
(Grant to Macurda [copy to Rudwick, 1968]). (In fact, as outlined in
Rudwick, 2017, the idea of paradigms had been prominent in my work
from the start.) The following year Grant and Cooper, as already
mentioned, published a preliminary account of many of their superbly
preserved Permian brachiopods from Texas (Cooper and Grant, 1969);
but it was purely taxonomic and made little reference to any kind of
functional interpretation. It is therefore perhaps not surprising that
Gould later told me that research by one of his students, on the
functional morphology of one of the bizarre lyttoniid brachiopods
(Leptodus) from Texas, had been blocked by Grant’s senior colleague:
‘‘Apparently, Cooper has such antipathy for the likes of you and me
that when he found out that this fellow was working with me and using
your approaches and ideas, he wouldn’t even let him look at most of the
specimens’’ (Gould to Rudwick, 28 November 1970).
After the New Orleans symposium was published (Macurda, 1968),
Gould told me, ‘‘I’m doing a review on the science of form (whatever
that is) for Earth-Sciences Reviews and am quoting MJSR[udwick] all
over the place’’; alluding to the paradigm method, he added, ‘‘It’s
amazing how many paleontologists are ashamed of their mechanistic
thinking in functional morphology’’ (Gould to Rudwick, 2 April 1969).
This major article on ‘‘Evolutionary paleontology and the science of
form’’ (Gould, 1970) opened with the claim that ‘‘A science of form is
now being forged within evolutionary theory’’; citing my original
formulation of the paradigm method (Rudwick, 1961), he stated that ‘‘The
approach of a structure to its paradigm provides the elusive criterion of
relative efficiency that any science of adaptation requires.’’ He linked my
work with Raup’s theoretical morphology, noting that ‘‘Actual forms
fill only a part of the total spectrum; their basic adaptation may be
grasped when we realize why unoccupied areas are not utilized.’’ He
argued that the combination of Raup’s ideas and mine, quantitative and
functional, introduced ‘‘a new methodology’’ that he called
‘‘quantifunctional’’; he pointed out that it suggested that in life’s history
‘‘parallelism and convergence are dominant phenomena, not mere
taxonomic nuisances’’ (Gould, 1970, pp. 77–78). Citing my functional
analysis of zigzag valve edges in fossil brachiopods (Rudwick, 1964a),
he argued that these phenomena involved ‘‘the attainment of
mechanical optima or Rudwickian paradigms’’ – by this time the quite different
meaning of ‘‘Kuhnian paradigms’’ was widely known among scientists –
simply because ‘‘they provide a selective advantage that leads, over and
over again, to their attainment in competition’’ (Gould, 1970, p. 110).
This made explicit what I had taken for granted: that the driving force
behind every approximation to a structure of paradigmatic form was
nothing other than ordinary Darwinian natural selection.
Gould’s paper illustrated this nascent ‘‘science of form’’ by reviewing
a wide variety of recent research by many different paleontologists,
setting it in a historical context that linked it back through D’Arcy
Thompson to nineteenth-century functional morphology. Referring to
the pattern of large-scale evolution that he claimed was now discernible
in the fossil record, Gould concluded that ‘‘We now have the outline of
a history [of life]: the weeding out of unsuccessful designs and multiple
evolution of mechanical optima’’; and that ‘‘major groups often have a
history that can be described on the basis of a few functional themes’’
(Gould, 1970, p. 111). In a later article on ‘‘D’Arcy Thompson and the
science of form’’ (Gould, 1971a), aimed at the quite different readership
of New Literary History, he emphasized again the crucial importance in
this context of thinking in ‘‘mechanistic’’ terms. Like Pantin (1951) long
before, though perhaps without knowing of that influential essay,
Gould argued that biologists should not be embarrassed to use the
language of ‘‘organic design,’’ and should not be inhibited by the
outworn historical legacy of Paley’s deistic ‘‘argument from design.’’
Seilacher’s ‘‘Constructional Morphology’’
The combination of Raup’s computer-aided theoretical morphology
with my own (and many others’) functional morphology, as proposed in
Gould’s ‘‘quantifunctional’’ approach, was taken further as a result of
Raup’s links with the paleontologists at Tu¨ bingen. This historic center
of research on ‘‘Pala¨obiologie’’ was now headed by Adolf Seilacher
), who had succeeded his mentor Schindewolf in 1964 (on the
background history of this German morphological tradition, see for
example Laubichler and Niklas, 2009). Seilacher’s innovative
‘‘Palichnologie’’ had earlier analysed ‘‘trace fossils’’ such as tracks and
burrows in terms of animal behavior (Seilacher, 1953a, b). Raup’s visit
to Tu¨ bingen resulted in a brief but important joint note in Science, in
which they interpreted certain trace fossils in terms of systematic
‘‘foraging behavior’’ by the unpreserved organisms; and this was now
supported by a ‘‘computer simulation’’ that convincingly replicated the
observed forms of the fossil tracks (Raup and Seilacher, 1969). This
represented an important further use of computers in the service of
Seilacher thanked Raup for having, in their seminar at Tu¨ bingen,
‘‘taught us how fossils can be understood in terms of theoretical
morphology.’’ But in fact this significant acknowledgement was appended to
a separate paper, published in Palaeontology, that was primarily
concerned with functional morphology (Seilacher, 1968, p. 281). Functional
morphology, Seilacher stated, was ‘‘a most important tool in the
interpretation of specialised forms that deviate ecologically from their
relatives’’; as examples he cited my bizarre richthofeniid brachiopods
and his colleague Vogel’s almost equally bizarre brachiopod Pygope
(Rudwick, 1961; Vogel, 1966). His own case was that of a fossil stalked
crinoid (Seirocrinus) of large size and unusual morphology, well
preserved in distinctive black shales that geologists attributed to originally
euxinic bottom conditions (in which crinoids could not have survived).
Seilacher suggested an elegant solution to this paradox: these crinoids,
unlike most others, had not grown upwards, plant-like, from
attachments on the sea-floor, but instead had dangled downwards from
attachments to unpreserved materials such as driftwood floating at the
surface. This accounted functionally – on predictable mechanistic
principles of organic design – for the crinoids’ aberrant morphological
Seilacher’s combination of theoretical and functional approaches to
fossil morphology was set out in a brief but important note in Lethaia, a
recently-founded multilingual journal (edited at Uppsala in Sweden)
‘‘for palaeontology and stratigraphy,’’ which had already shown itself to
be receptive to newer kinds of research. Seilacher’s note (
titled modestly an ‘‘Arbeitskonzept’’or working draft; it was intended to
introduce further papers by himself and his colleagues, on what he
defined as ‘‘Konstruktions-Morphologie.’’ Seilacher adopted the visual
idiom of the triangular or ‘‘ternary’’ phase-diagrams used by physical
chemists, mineralogists and other scientists: he depicted ‘‘constructional
morphology’’ as the product of three ‘‘aspects’’ or ‘‘factors’’ at the
corners of a triangle: ‘‘historical-phylogenetic,’’ ‘‘ecological-adaptive’’
and ‘‘fabricational’’ [bautechnischer] (Figure 6).
Of these, the first two need no special explanation. In principle, it is
obvious that the morphology of an organism can be described in terms
of its phylogenetic legacy, developed as an anatomical ground-plan
[Bauplan] in the course of its evolutionary history: to interpret
organisms in this way had been the goal of much paleontological research ever
since Darwin. Equally clearly, the pre-Darwinian tradition of functional
morphology had now been revived in an evolutionary context: Seilacher
referred to my methodological paper (Rudwick, 1964b) as having given
a new uplift [Aufschwung] to Othenio Abel’s ‘‘Pala¨obiologie’’ (Abel,
1912), exemplifying this ‘‘ecological-adaptive’’ factor or
‘‘FunktionsMorphologie.’’ The third corner of Seilacher’s triangle was perhaps more
puzzling to those unfamiliar with his intellectual heritage, namely the
kind of evolutionary theorizing advocated earlier by Schindewolf and
other German-speaking paleontologists. Seilacher himself translated
‘‘bautechnisch’’ as ‘‘architectural,’’ but later (and better) as
‘‘fabricational’’ (Seilacher, 1979, p. 191). It drew attention to the basic
constraints on organic form that reflect what is physically ‘‘possible in
this universe of ours,’’ as Pantin had put it, independently of either the
Bauplan or phylogenetic legacy of the organism, or its functional
requirements or adaptations. In Raup’s ‘‘theoretical morphology,’’ for
example, these fundamental constraints were expressed in the matrices
of all possible spiral shell forms, which his computer programs had so
elegantly generated and displayed. They were likewise expressed in my
emphasis on the limited alternative classes of design (grilles, meshes,
slits) possible for protective devices in the specific case of brachiopods:
analogous, say, to the possible classes of designs for bridges, which
Thompson and Pantin had both invoked. More generally, they were
conclusions.’’ Although he conceded that Clarkson’s studies of trilobite
vision showed that on occasion it could ‘‘produce excellent results,’’ he
downgraded it from a ‘‘method’’ to a mere ‘‘point of view’’ or
‘‘approach’’ (Grant, 1972, pp. 235–236).
In a paper submitted at almost the same time as Grant’s, but to
another journal, Cowen (
) suggested an important extension to our
earlier interpretation of both richthofeniids and lyttoniids. As already
noted, these bizarre brachiopods had ventral valves with spreads of
shelly material extending far beyond the deeply recessed dorsal valve.
These shelly tracts must have been secreted by, and covered in, equally
extensive spreads of exposed mantle tissue. Cowen argued that they
were closely similar to the spreads of permanently exposed tissue
around the valve edges of living ‘‘giant clams’’ (Tridacna), which are
prominent on many tropical coral reefs. In these molluscs this tissue
incorporates symbiotic zooxanthellae that provide, by photosynthesis,
an important supplementary source of energy. If richthofeniids and
lyttoniids had incorporated similar symbionts, it could explain further
features of their strange morphologies (in addition to those explained by
their putative feeding mechanisms). No direct evidence for this kind of
symbiosis had of course been preserved in the fossils; but the inference
could be supported indirectly, if the ordinary clues of paleoecology
indicated that these aberrant brachiopods, like the living giant clams,
had been confined to clear shallow tropical waters such as those of reef
environments. Cowen argued that the known geographical range and
paleoecological context of these Permian faunas were indeed compatible
with this inference.
While Grant’s critique of the paradigm method was still in press, he
himself unwittingly added weight to Cowen’s idea. He published a
straightforward paleoecological interpretation of the extensive ‘‘reefs’’
(‘‘bioherms’’) in the Permian rocks of the Glass Mountains (Grant,
1971). He showed that they had been built, almost certainly in tropical
environments similar to modern coral reefs, by many unrelated
organisms, among which the aberrant brachiopods were certainly prominent.
I had in effect withdrawn from this debate, mainly under the
practical pressures of my new teaching duties in what was for me a radically
new academic field. But while Cowen was preparing a response to Grant
we received unanticipated support from Paul, who, as mentioned
earlier, was working on the functional morphology of the extinct cystoid
echinoderms. Paul told us he was using our interpretations of
brachiopods in a teaching course on ‘‘controversial topics in
palaeontology,’’ and he suggested that he himself should write a paper in response
to Grant’s critique. However, he warned us that ‘‘whereas I reject
Grant’s general criticisms of the paradigm method I find his
interpretation of Prorichthofenia and the lyttoniids very persuasive’’ (Paul to
Rudwick, 11 July, 23 November 1973). After some discussion, Paul and
Cowen agreed to write complementary papers for Lethaia: Paul on the
method in general, Cowen on the specific case of the bizarre
At the start of his paper, Paul stated that ‘‘The most important
feature of the paradigm method is that it allows functional hypotheses to
be tested [and] therefore offers the possibility of removing functional
interpretations from the realm of speculation’’ (Paul, 1975, p. 15;
emphasis original). This was wholly in accord with my own conception
of the method. Unfortunately, however, Paul summarized paradigms as
structures ‘‘which are 100% efficient in performing proposed
functions.’’ This laid his argument open to misinterpretation, in that it could
obscure the crucial distinction between the ideal and the paradigmatic.
This in turn could divert attention from the intrinsic limitations of the
latter, as emphasized for example by Seilacher: namely, that
morphologies are bound to have evolved within the constraints of
phylogenetic legacy and fabricational possibility (and that they may often
have been necessary compromises between formally conflicting
functions). Even the most effectively ‘‘paradigmatic’’ designs, evolved
through natural selection, were therefore bound to be less than ‘‘ideal.’’
However, Paul did analyze effectively the differences between Carter
and myself in our functional interpretations of zigzag valve edges and
tubular external spines in bivalves and brachiopods; he pointed out that
in certain respects the morphologies were not strictly comparable, and
hence that both sets of interpretations were plausible for their respective
cases. In a brief section on richthofeniids (deleted before publication to
avoid overlap with Cowen’s paper), Paul endorsed some of Grant’s
reasons for doubting the ‘‘flapping’’ interpretation while rejecting others
(Paul, undated draft typescript). The published paper concluded that,
notwithstanding Grant’s criticisms, the paradigm method itself was
fundamentally valid, even though its application might in some cases be
problematic and fallible.
In Cowen’s paper, duly printed immediately after Paul’s, he defended
what he now named a ‘‘flapping valve’’ or ‘‘rhythmic-flow’’ feeding
mechanism for the richthofeniid brachiopods; like Paul, he also used the
case to review the paradigm method itself after more than a decade of
debate, and to defend its validity (Cowen, 1975). He showed that
Grant’s dismissal of analogies with any kind of pump was misconceived,
since the proposed ‘‘flapping’’ was not a pump-like mechanism, but
rather one of rhythmic or ‘‘tidal flow’’ in and out of the richthofeniid
shell (rather like our own action in breathing). Cowen argued that a
rhythmic mode of feeding that had differed radically from normal
ciliary suspension-feeding was not intrinsically improbable or inefficient,
since the unusual reef environment of the aberrant brachiopods might
well have made unusual categories of floating food available for capture
and collection. Cowen responded in detail to Grant’s other objections,
noting particularly how the morphology of mature richthofeniids would
have made any conventional suspension-feeding system highly
inefficient, because the inhalant and exhalant water currents could not have
been spatially separated. He warned Grant that an ‘‘appeal to Occam’s
razor in this context is a very dangerous gamble.’’ Finally, he pointed
out that for all these aberrant organisms ‘‘there is no quarrel over data,
but only over their interpretation’’; he hoped that the future publication
of the Texas fossils by Cooper and Grant would enlarge the available
‘‘data base’’ of morphological detail and ‘‘allow this particular dispute
to be put to rest in a definitive way.’’
These papers by Paul and Cowen were followed immediately, in the
same issue of Lethaia, by a brief ‘‘reply’’ by Grant (
). Its title,
‘‘Methods and conclusions in functional analysis,’’ made it clear that his
criticism was intended to reach far beyond the specific case of alleged
‘‘flapping’’ in richthofeniids. He now claimed, rather unconvincingly,
that his earlier paper (
) had not been intended to reject the
paradigm method as such, but only to criticize it and to extend it ‘‘beyond
the structural and mechanistic constraints of the original formulation.’’
Once again, as Gould had noted earlier, ‘‘mechanistic’’ was being
treated almost as a dirty word, or at least as an undesirable limitation.
‘‘The crux of the matter,’’ Grant claimed, ‘‘lies in the evidence’’: namely,
what he had earlier given for the form of the lophophore (as a
ptycholophe) in all productide brachiopods, regardless of size and
including richthofeniids. Ironically, the one new piece of evidence that he
described as invalidating the idea of ‘‘flapping’’ could more readily be
interpreted in favor of it. This was a particular specimen of the
richthofeniid Hercosestria (the former P. uddeni) in which another more
‘‘ordinary’’ brachiopod (Composita) had grown within, and been
confined to, the totally enclosed space between the ‘‘trap-door’’ dorsal valve
and the unbroken protective shelly mesh above it (Figure 9). Grant
inferred, justifiably, that this brachiopod must have penetrated the mesh
and entered that space as a tiny planktonic larva, settled there and then
grown to adult size. But he implied that it must have done so while the
richthofeniid was still alive, although it was highly unlikely that any
larva would, or indeed could, settle on or attach itself to the live mantle
tissue of another brachiopod. Even if it had done so, and the dorsal
valve of this particular richthofeniid had been unable to open beyond a
small angle, let alone to ‘‘flap,’’ the much wider and accurately arcuate
form of the shelly mesh immediately above it was left unexplained;
certainly no efficient system of steady suspension-feeding currents would
have been possible. Grant’s interpretation of this one specimen
displayed a serious lapse in biological imagination, which was bound to
raise doubts about his wider interpretation.
Grant did not send his paper to his critics in advance, and they first
read it when all three papers were published together in Lethaia. Cowen
responded briefly in a note distributed with offprints of his own paper,
underlining the points just summarized, and in particular rejecting
Grant’s interpretation of the trapped Composita. He concluded, ‘‘I
stand by my interpretation of the tidal-flow feeding mechanism as the
best working hypothesis at the moment to explain the complex
morphology of these brachiopods’’ (Cowen, typescript note, 1 July 1975).
Cowen’s affirmation, combined with Paul’s effective defense of the
underlying method despite his doubts about the particular case, showed
there was still some life in the idea of paradigms.
However, Cooper and Grant were unconvinced. In their huge
ongoing monograph on the Permian brachiopods from the Glass
Mountains, and before the Lethaia papers appeared, they had already
rejected any ‘‘pulsating’’ mechanism for either lyttoniids or
richthofeniids. But they did so without any thorough functional analysis
of the morphological features that were in contention (Cooper and
Grant 1972–1977, pp. 414 , 927–928 ). In fact their
specimens were portrayed with a poor quality of reproduction and in a
conventional manner that made any such analysis almost impossible.
They even illustrated (pl. 127) some of the specimens of Poikilosakos
(not from the Glass Mountains) that I had used for my functional
interpretation of this probably ancestral lyttoniid (Rudwick, 1971); yet
they did not cite that paper – although it had been published in
Cooper’s own Festschrift – even to reject its conclusions. This seemed to
confirm what Gould had earlier identified as Cooper’s ‘‘antipathy for
the likes of you and me,’’ though the reasons for it, scientific or personal
or both, remained unclear.
Paleobiology Established, and Paradigms Marginalized
Since Grant’s attack was not answered in published form, some later
commentators assumed that he had effectively discredited the paradigm
method once and for all. More generally, however, and notably in
Germany, it continued to be recognized as an essential component in
the functional interpretation of fossil morphology. For example, in a
review of ‘‘Controlling [Lenkende] and limiting factors in evolution,’’
Wolf-Ernst Reif (
) noted the crucial role of paradigms in his
senior colleague Seilacher’s tripartite analysis (Reif, 1975, pp. 143–144).
Reif also co-authored a significant review of the ‘‘form-function
complex,’’ which combined Raup’s theoretical morphology with the
functional paradigm concept in what was in effect Gould’s
‘‘quantifunctional’’ approach; but Reif and his collaborator argued that
sufficient attention was still not being given to the third corner of
Seilacher’s triangle, the ‘‘fabricational constraints’’ [bautechnische Zwa¨nge]
that necessarily limit the functional adaptations that can in reality
evolve, and that go far to explain the prevalence of evolutionary
parallelism and convergence (Reif and Robinson, 1975). (That this paper
was co-authored by an anglophone scientist was another sign of the
growing international influence of Seilacher’s school.)
At much the same time an analysis of the foundations of ‘‘functional
morphological models,’’ this one published in Chicago, judged that my
interpretation of zigzag valve edges in brachiopods, as having been
protective in function (Rudwick, 1964a), was ‘‘the best documented
example [of] the paradigm approach’’; that it was more predictive for
that function than for any other; and that therefore ‘‘Rudwick’s idea is
the one most accepted’’ (DeMar, 1976). Yet the same author claimed
that ‘‘evolution interferes with the application of the paradigm
approach,’’ because it would not work if a structure serving one function
with great efficiency had in fact gradually evolved into serving another
with equal efficiency. However, this overlooked my argument that
attributing a likely function to a given structure, by comparing it with
the paradigm for that function, was methodologically a separate issue
from the reconstruction of its phylogenetic origin (Rudwick, 1964b). At
least in principle, therefore, it would be possible – without abandoning
or even modifying the paradigm method – to trace a seamless
evolutionary transition from one function to another, by way of structural
intermediates that would represent a shifting balance of compromises
between them. Once again the deployment of the paradigm method was
being hampered by a misunderstanding of its methodological
By the mid-1970s, the interpretation of the morphology of
invertebrate fossils – whether emphasizing its phylogenetic, functional or
fabricational aspects – had become an established component of
‘‘paleobiological’’ research (work on vertebrate fossils remained largely
separate, both intellectually and socially, and is beyond the scope of this
article). Other and complementary approaches, such as the
paleoecological and paleobiogeographical, and of course the evolutionary, were
also flourishing. In Continental Europe such Pala¨obiologie had long
been recognized as a distinctive field of research, exemplified by Abel’s
earlier journal Palaeobiologica. In North America, however, a
recognition that these approaches were distinct from the taxonomic and
stratigraphical focus of traditional ‘‘paleontology’’ was first signaled
unequivocally in 1975, with the foundation of Paleobiology. The
original purpose of this new journal was to complement the more traditional
Journal of Paleontology by encouraging biologists, and particularly
evolutionary biologists, to take a greater interest in what the study of
fossils could contribute to their science. In the course of a lively
discussion among American paleontologists (Sepkoski, 2012, pp. 185–195),
Valentine suggested that the proposed journal would get off to a flying
start if it had ‘‘a first year with a heavy scattering of eminent biologists’’
among its authors. Among those initially more sceptical, Grant was
concerned that it might ‘‘encourage speculation that is not firmly based
on geological and paleontological documentation’’; he may have had in
mind ‘‘speculation’’ about the unobservable functions of fossil
An enthusiastic advocate for the new journal was Schopf, who
became its first editor (nominally a co-editor). In a draft report on its
feasibility, he outlined a broad range of topics that it might cover,
anticipating that ‘‘most volumes will deal with biological or
paleobiological aspects of morphology, biochemistry (organic and inorganic),
populations, faunal provinces, communities and ecosystems’’ (Sepkoski,
2012, p. 190). This list was later printed in the inaugural issue of
Paleobiology as a brief statement of editorial policy; it is notable that
morphology was given first place. Valentine’s hope that the first authors
might include some heavyweight evolutionary biologists was not
fulfilled, but the papers in the first issue did exemplify a broad and
inclusive conception of the science. The very first paper, co-authored by
Gould, was a computer-aided analysis of the ‘‘theoretical morphology’’
of some enigmatic Paleozoic fossils (receptaculitids) of highly uncertain
affinities (Gould and Katz, 1975). Other papers dealt with the functional
morphology of both living and fossil organisms: Stanley, for example,
reported on his ‘‘experimental analysis of burrowing’’ to explain ‘‘why
clams have the shape they have’’ (Stanley, 1975). And the new
quantitative or nomothetic paleontology was represented by Raup’s paper on
‘‘taxonomic survivorship curves’’ (Raup, 1975), and by a paper by him
and the others in the ‘‘MBL’’ group, in which ‘‘rates of evolution’’ were
evaluated by the quantitative measure of the number of morphological
terms needed by paleontologists to describe fossils of different major
groups (Schopf et al., 1975). Here morphology was quantified in the
service of evolutionary theory but, once again, shorn of its functional or
Nonetheless the functional approach still held its own. In 1977 Raup
became the new president of the Paleontological Society and – as he
admitted, or perhaps boasted – the first who had never described or
named any new species of fossil. But in an irenical presidential address
he insisted that any theory proposed by himself ‘‘and other so-called
paleobiologists’’ should always be based on the kind of morphological
description which members of the Society traditionally practiced: the
two kinds of research were not antagonistic but complementary. On the
theme he chose for his address, ‘‘The extinction problem,’’ he
emphasized the sheer universality of extinction, and that it did not imply any
deficiency in the organisms affected: ‘‘only good functional morphology
could tell us that’’ (Raup, 1978, p. 522).
As the decade ended, a pair of brief but effective articles in a new and
substantial Encyclopedia of Paleontology (Fairbridge and Jablonski,
1979) showed that the foundations of morphology had not been
forgotten. The first article, on ‘‘Morphology, Constructional,’’ summarized
Seilacher’s tripartite conception of morphology, explained the heuristic
role of my ‘‘mechanical paradigm, an optimum model of maximal
efficiency,’’ and noted how many papers inspired by Seilacher’s work
had been published since the start of the decade (Thomas, 1979). In the
second article, on ‘‘Morphology, Functional,’’ Cowen summarized a
range of functional interpretations of fossils; he gave a balanced
assessment of the paradigm method, its potential and its problems,
judging that it was ‘‘chiefly useful in promoting clarity of thought in
functional analysis’’ (Cowen, 1979).
In the same year, however, this still quite prominent role for
functional morphology as an essential component of ‘‘paleobiology’’ was
radically questioned by Gould, in a paper nominally co-authored with
his senior Harvard colleague Richard Lewontin (1929–), which was
announced as a ‘‘critique of the adaptationist programme’’ (Gould and
Lewontin, 1979). Gould’s often iconoclastic ideas, combined with his
attractive prose style, had propelled him within a few years into a
position of controversial prominence among evolutionary biologists;
and his monthly articles in Natural History (from 1974), many of them
subsequently reprinted in book form (first in Gould, 1977), were making
him equally well known as a ‘‘public intellectual.’’ Unsurprisingly,
therefore, his paper on ‘‘The spandrels of San Marco’’ was as influential
and as controversial as his earlier paper (with Eldredge) on punctuated
‘‘The spandrels of San Marco’’ – the enigmatic title of the paper was
all the more provocative for being published in the highly
respectable Proceedings of the Royal Society in London – opened with
an extended analogy drawn, as often in Gould’s writing, from his own
wide cultural interests. In any cruciform church built in the Byzantine
tradition (the cathedral in Venice was cited just because it is widely
known), the central circular dome is supported on four semicircular
arches; the geometrically inevitable intervening spaces are filled with
vaulting in the form of four concave triangular spandrels. These four
spandrels were commonly used, as they are in St Mark’s, to display
prominent images of the four Evangelists. But no art historian would
claim that spandrels were designed for that purpose: as Gould rightly
put it, spandrels are ‘‘necessarily architectural by-products of mounting
a dome on rounded arches.’’ However, this analogy, with its obvious
allusion to the bautechnischer or fabricational factor in Seilacher’s
analysis, was then used by Gould to dismiss all interpretations of
morphology that anticipated finding adaptive significance in any and
every feature of an organism. This ‘‘adaptationist programme,’’ as
Gould termed it, was criticised scornfully with an allusion to Voltaire’s
ever-optimistic Dr Pangloss: in the article’s title it was described as ‘‘the
Panglossian paradigm’’ (the latter word being used here, of course, in
Kuhn’s sense). This was coupled with a repeated reference to ‘‘adaptive
stories,’’ with its obvious allusion to Rudyard Kipling’s ‘‘Just-So
Stories’’ for children, on ‘‘How the Leopard got its Spots’’ and other
similarly entertaining tales.
My interpretation of zigzags on the valve edges of fossil brachiopods
(Rudwick, 1964a) had the dubious distinction of being cited in first
place as an example of such ‘‘adaptive stories’’: it was dismissed as the
product of a vacuous policy of ‘‘If one adaptive argument fails, try
another.’’ Surprisingly, in view of Gould’s previously enthusiastic
acceptance of the method of paradigms (in my sense of the word), this
ignored its heuristic power to test putative functions and to infer that
one was more likely than another; and so it also ignored the capacity of
the method to generate progressively better adaptive interpretations.
Not all ‘‘adaptive stories’’ were equally plausible, so any prescription to
‘‘try another’’ if the first failed – though this was not phrasing I had ever
used – was a potentially productive strategy, not a fallacious dead end.
There was a serious flaw in Gould’s architectural analogy, which was
not adequately acknowledged at the time. The fourfold spandrels of any
cruciform Byzantine church were indeed designed – and well adapted –
to complete the vaulting over the interior and to strengthen the whole
structure. But once they were there as an integral part of the structure,
they were equally well adapted to display the fourfold imagery of the
four Evangelists, as an integral part of an iconography designed to
express symbolically the cosmic meaning of the whole building (with,
for example, the ‘‘Christ Pantocrator’’ often sited at the central point of
the dome above the spandrels, and at the unique center of the
iconography). Gould’s use of an analogy with spandrels failed to acknowledge
that one and the same morphological feature can readily serve two
functions simultaneously and with equal efficacy, if their respective
paradigms coincide or at least overlap. As with domes and spandrels,
the historical origin or phylogeny of the features is a separate question:
one feature and function may well have preceded, and been a necessary
structural precondition for, another feature and function.
Gould’s ‘‘Spandrels’’ paper was a plea, well argued although
provocatively expressed, for more attention to be given by biologists
(including paleobiologists) to the fabricational constraints that limit the
‘‘perfection’’ of adaptations produced under natural selection. But the
paper’s attractive and accessible style was such that its side effect,
intended or not, was to devalue all attempts to identify the functions that
organic structures may have served in the unobservable deep past.
Gould’s demotion and derisive near-dismissal of the functional or
adaptive ‘‘aspect’’ of Seilacher’s tripartite analysis had a profoundly
damaging impact on paleobiology in the following decade or more. This
was hardly compensated by the positive impact of his emphasis,
following Seilacher, on the combination of phylogenetic and fabricational
‘‘aspects.’’ The intellectual or biographical reasons for Gould’s dramatic
change of mind on the place of functional morphology in paleobiology
remain somewhat obscure, but were certainly related in part to his
changing stance in contemporary debates among evolutionary theorists,
which highlighted putatively non-functional or non-adaptive aspects of
morphology (Dresow, 2017).
The year after the ‘‘Spandrels’’ paper was published, Gould made his
critique of functional morphology more explicit in an article in
Paleobiology that was his contribution to a series on the ‘‘status of
paleontology [in] 1980’’; he warned at the start that ‘‘This paper is not a review
article; it is a partisan statement.’’ In ‘‘The promise of paleobiology as a
nomothetic evolutionary discipline’’ (Gould, 1980) he presented his
case, even more forcefully than before, for rejecting the traditional
idiographical goals of paleobiology in favor of the nomothetic: ‘‘much
paleobiological work continues in the ‘‘empirical law’’ tradition – it
accumulates cases in the hope that some useful generality will emerge.’’
He claimed that this hope was in vain, as shown by the example – which
he sandwiched between those of ‘‘community reconstruction’’ (i.e.,
synecology) and ‘‘biostatistics’’ – of ‘‘mechanistic functional
morphology’’ (Gould, 1980, p. 101):
The flowering of functional morphology has yielded a panoply of
elegant individual examples and [i.e., but] few principles beyond the
unenlightening conclusion that animals work well… But I think
that higher hopes were once held (Rudwick, 1964[b]). I, at least,
once harbored the naı¨ ve [sic] belief that a simple enumeration of
more and more cases would yield new principles for the study of
form (Gould, 1970)…. I suspect that functional morphology will
fulfil its promise [only] when it probes the situations in which
animals are not well designed – developmental, phyletic, and
architectural [i.e., fabricational] constraints as marks of history
(Seilacher, 1972; Gould and Lewontin, 1979). As a key issue, why is
morphological space so sparsely populated, but so clumped where
it is occupied? How much of clumping and non-occupation reflect
[respectively] good and untenable design, how much the constraints
Gould’s reference to Raup’s conception of a potential ‘‘morphospace’’
only partially filled with real organisms, past or present, was strangely
blind to the role of functional morphology in explaining – with some
success, as Raup certainly recognized – why, within the ‘‘constraints of
genealogy,’’ organisms are ‘‘clumped’’ as they are. In other words, he
failed to acknowledge that the boundaries between the ‘‘occupied’’ and
‘‘sparsely populated’’ parts of a morphospace could only be explained
by attending not only to the constraints that limit optimality of function
but also to the pressures of natural selection towards attaining that
optimality as fully as possible.
In this context Gould specifically criticized the paradigm method,
and used a past tense that implied it was already invalidated and
obsolete. While conceding that ‘‘it clarified procedure and directed
attention to the central [sic] problem of non-optimality,’’ he claimed
that ‘‘It foundered on the difficulty of specifying function a priori (in
order to know what paradigm to construct).’’ This, however, was
tantamount to asserting that any scientific hypothesis would be invalidated,
even before its predictions were subjected to empirical test, if it could
not be selected in advance from among other and rival hypotheses. Of
course, such a procedure would not be considered acceptable in any
other scientific situation. How I had first conceived of zigzag valve edges
as possibly protective devices – by trying hard to imagine ‘‘what it is like
to be a brachiopod,’’ even to the point of dreaming of being one! – was
irrelevant to my attempt to test the idea by analyzing the geometry of
zigzag slits, both paradigmatic and real, and then concluding that a
protective function was far superior in explanatory value to its
Before writing this review Gould had asked twenty other
paleontologists for their opinions on several current trends in the science;
among his respondents (to name only those already mentioned here)
were Cooper, Cowen, Grant, Hallam, Raup, Schopf, and Valentine
(Gould, 1980, p. 116). On functional morphology, Gould reported that
‘‘Supporters cite improved understanding of how individual taxa and
broader groups functioned; debunkers deplore the speculative quality of
some work, based on na ı¨ve (and downright false [sic]) assumptions that
everything is adaptive and that natural selection produces optimal
design.’’ On this crucial issue, Gould recorded that ‘‘My own increasingly
ambivalent feelings about standard functional morphology arise from
its failure to generate new theory,’’ in that it had not developed beyond
the basic premise that all organisms are well adapted: ‘‘The theme of
good design has not been productive of any new or general insight.’’ The
only way to escape from this dead end, he concluded, was to reject the
‘‘rigid adaptationist program’’ and to accept that ‘‘Organisms are not
optimizing machines; they are historical objects, constructed by
inherited Baupla¨ne, modes of development, and mechanical properties of
building materials’’ (p. 111). He did not explain, let alone justify, this
claim that the historical legacy and ontogeny of the organism, and the
fabricational constraints on its anatomy, are incompatible with the
functional optimizing of its organic design – within those sets of
limitations – under natural selection.
Gould’s critique of the ‘‘adaptationist program’’ had less impact
outside the United States. In 1980, for example, the Pal a¨ontologische
Gesellschaft in Germany commissioned a series of authoritative reviews
of recent research; and the very first, edited by Reif of Tu¨ bingen, was on
Funktionsmorphologie (Reif, 1981a). Reif’s own introduction, on
‘‘Concepts and methods of functional morphology,’’ included a section
on the paradigm method. Here he noted that since 1975, when the
wellknown trio of papers by Paul, Cowen and Grant (already described
here) was published, ‘‘the problem has vanished from the literature:
wrongly, for it was just this discussion that resolved many
misunderstandings’’ (Reif, 1981b, p. 15, my translation). The following year Reif
enlarged on this ‘‘problem’’ in a paper that described functional
morphology as lying uncomfortably ‘‘on the procrustean bed of the
neutralism-selectionism debate’’ in evolutionary theorizing (Reif, 1982): this
identified what was apparently the major factor in Gould’s change of
mind about the paradigm method (Dresow, 2017). Reif noted how the
‘‘constructional’’ approach to morphology, as pioneered by Seilacher,
had emphasized the intrinsic constraints on the evolutionary optimizing
of functional structures; at the same time, however, he identified
functional inference as ‘‘one of the most important keys to
paleoauteocology,’’ which in turn was ‘‘one of the most constitutive fields of
paleobiology’’ (Reif, 1982, p. 53). He judged that in this respect
mechanistic analogues were of greatest value: ‘‘The focal point here is,
of course, Rudwick’s (1964[b]) paradigm method.’’ That ‘‘the discussion
has virtually come to a stop since 1975’’ was again attributed to the
growing appreciation of the phylogenetic and fabricational constraints
on functional optimality: ‘‘Rudwick was aware of this and formulates it
in an admittedly not very powerful way, but since Rudwick this aspect
has won more attention’’ (Reif, 1982, pp. 53–54). In other words, Reif
attributed the decline in the relative prominence of functional
reconstructions in paleobiology – and hence also in the use of the paradigm
method – to the perceived importance of Seilacher’s other two
‘‘aspects.’’ However, this did not address the continuing need to find an
adequate way in which all three ‘‘aspects’’ or ‘‘factors’’ could be related
Immediately following Reif’s quite positive evaluation, the same
German journal printed ‘‘A critical re-evaluation of the paradigm
method of constructional inference’’ (Signor, 1982). Its author noted
that ‘‘the paradigm method of functional analysis was well received and
is now commonly employed.’’ But it was said to be ‘‘fundamentally
flawed by its crucial assumption that a single optimal solution (the
paradigm) is the predictable outcome of evolution by natural selection.’’
This however assigned roles to prediction and singularity that were
altogether absent from the original formulation of the method: for
example, the multiplicity and evidently polyphyletic origin of zigzag
valve edges and other putatively protective devices in brachiopods
clearly illustrated how an abstract geometrical paradigm was bound to
take many concrete forms, depending on the materials available during
ontogeny and as the legacy of phylogeny (Rudwick, 1964a).
Regrettably, this author’s critique, like some others, showed an inadequate
grasp of the empirical details of the examples that had been offered in
illustration of the method: in this case, only my analysis of
Prorichthofenia (Rudwick, 1961) was cited, and even this was mentioned
only in passing, not criticized in detail.
I have suggested that Gould’s ‘‘Spandrels’’ paper of 1979, with its
striking volte-face on the value of functional morphology in general and
the paradigm method in particular, was deeply deleterious to this kind
of paleobiology, because by that time Gould himself had become such
an influential ‘‘public intellectual’’ that his word was widely taken to be
the truth on any matter of evolutionary biology. As Cowen recalls,
‘‘Gould had a dreadful impact on invertebrate functional studies. At
least, I blame him: NSF [National Science Foundation] funding for
invertebrate functional projects simply dried up. Functional
morphology went on in Canada, Britain and Europe, of course’’ (Cowen to
Rudwick, 4 September 2016). In the rather separate world of vertebrate
paleontology, the possible functions of, for example, the morphological
features of dinosaurs had never faded from the attention of the relevant
scientists: on both sides of the Atlantic the ‘‘ways of life’’ of such
animals continued to be the subject of lively scientific debate, and were
often reconstructed in striking museum exhibits (and later in animated
television programs), which fascinated the general public.
The paradigm method itself continued to be reviewed explicitly from
time to time, at least to the end of the century. For example, within a
comprehensive collection of essays on the Functional Morphology of the
Invertebrate Skeleton (Savazzi, 1999), Paul returned to the fray to
defend once again the validity and value of ‘‘paradigms’’ in paleobiology.
And he asked, significantly, ‘‘I wonder why it is [that] the paradigm
method has attracted so much criticism’’ (Paul, 1999, p. 28), though at
the time he did not suggest an answer.
At the start of the new millennium, the first quarter-century of
Paleobiology was celebrated with a special book-length issue titled Deep
Time (Erwin and Wing, 2000). Its editors emphasized how biologists still
needed to take more seriously the temporal dimension of the complex
history of life on Earth, which only paleontology could supply. The
volume was an effective display of what ‘‘paleobiology’’ now had to
offer, as distinct from the traditional kinds of paleontology. Among
many fine essays, one with the informative subtitle ‘‘functional analysis
in paleobiology’’ had a striking main title: ‘‘Invention by evolution’’
(Plotnik and Baumiller, 2000). This signalled its authors’ recognition
that ‘‘mechanistic’’ thinking remained crucially important – though not
unproblematic – in the functional analysis of fossils and their
interpretation in terms of the adaptations generated in the course of
evolution. This thorough survey of the state of functional analysis at the start
of the new century showed not only how much valuable work was
continuing to be published, but also how far the analysis of invertebrate
fossils had come to be integrated with that of vertebrates (which for
practical reasons have been beyond the scope of the present article). So
for example the paradigm method was said to have been largely
supplanted by – or, rather, subsumed within – the methodology of
‘‘biomechanics,’’ with many of its best examples drawn from the
mechanical analysis of the skeletons and musculature of living and fossil
However, this assimilation of paradigms into biomechanics had the
inadvertent effect of glossing over the crucial epistemological contrast
between paleontology and neontology. As this brief history of the
paradigm method has illustrated, distinctive epistemological problems
are inherent in the functional interpretation of fossil organisms, simply
because they cannot be observed alive or made the subjects of direct
experiment. The problems of understanding the biomechanics of flying,
for example, are not the same for pterosaurs as they are for bats; the
problems of reconstructing the hydrodynamics of feeding mechanisms
in aberrant Permian brachiopods are not the same as they are for
observing those of brachiopods now alive in New Zealand.
By the turn of the century, much of the earlier work described in the
present article and its predecessor (Rudwick, 2017) had fallen out of
sight: such are the brief half-lives of most scientific papers. For example,
in the essay just mentioned, my methodological analysis of paradigms
(Rudwick, 1964b) was the only one of my publications to survive among
the sources cited. This was a pity, not for any personal reasons but
much more because a closer reference back to my own and related
papers on specific cases of functional analysis might have helped avoid
the widespread but mistaken impression that a paradigm design was by
definition one that was ‘‘ideally efficient,’’ or else that it was merely a
source of imaginative ideas about possible functions. It might have
focussed attention instead on the capacity of the paradigm method to
provide testable models of what the optimizing of a function, under
natural selection, might be expected to have generated in any specific
circumstances of phylogenetic legacy and fabricational constraint.
In conclusion, my frequent use of the phrase ‘‘organic design’’ in
relation to the paradigm method may be thought to disclose the hitherto
barely mentioned ‘‘elephant in the room’’: namely the influence, both
positive and negative, of the idea of ‘‘design’’ in the biological sciences.
Positively, the concept of ‘‘organic design’’ has unquestionably been of
outstanding value in the development of functional morphology ever
since the time of Cuvier in the early nineteenth century, and not least in
the influence of D’Arcy Thompson’s work in the early to mid-twentieth
century. Negatively, its early historical association with William Paley’s
deistic ‘‘argument from design’’ may have inhibited later paleontologists
from exploring wholeheartedly the possible role of ‘‘organic design’’ in
fossil organisms (it has sometimes, particularly in the anglophone
world, mistakenly been taken to be incompatible with evolutionary
thinking). This factor may have been aggravated by the rise of
fundamentalistic creationism – and more recently of ‘‘intelligent design’’ ideas
– to cultural and even political prominence in the United States (though
not in Europe). But I do not recall that back in the 1960s and 1970s my
emphasis on ‘‘organic design,’’ derived in my case particularly from my
early personal contact with Pantin (who was no fundamentalist!), was
ever criticized for giving comfort to creationists.
Gould’s dramatic change of mind about the value of the paradigm
method, switching from enthusiastic endorsement to somewhat derisory
dismissal, came much too late to have had any influence on my own
earlier (and, at the time, quite difficult) decision to switch my teaching
and research in mid-career from paleontology to the history of this and
related sciences. I followed Gould’s later work and that of my other
former colleagues with very great interest but, inevitably, with declining
involvement. Conversely, Gould was well aware of my historical
research, mentioned it in his essays, and published reviews of some of it
with evident appreciation. Certainly we remained personal friends.
After what turned out to be our last meeting before his tragically early
death, he wrote: ‘‘Great to see you. Always so many good ideas and
conversations. To quote an old favorite line: I always feel as though half
my ideas come out of Rudwick’s brain’’ (Gould to Rudwick, 28 August
). The allusion to Darwin’s famous remark to his mentor Charles
Lyell was flattering to me and hardly modest about himself; but its
reference was probably as much to my historical research as it was to
my earlier work in paleobiology.
As in the article to which this is the sequel, it is a great pleasure to
thank David Sepkoski for first urging me to attempt this piece of
twentieth-century historiography. I also thank Richard Cowen for
giving me masses of fascinating first-hand information on these and
later developments in paleobiology; Euan Clarkson, for giving me
images from his early articles; and Chris Paul, for filling in some
important gaps in my recollections. Simon Conway Morris, Martina
Ko¨ lbl-Ebert and Paolo Tamborini also read a draft of this article and
gave me many valuable suggestions for its improvement. In checking
the dates of the scientists mentioned here by name (in my opinion,
years-of-birth are important for giving a sense of the ages and
generations of those involved), I have been saddened to realise how, by not
tackling this research project earlier in my own career, I have missed
the opportunity to discuss the drama with some of its most important
players: particularly my friends the late Dave Raup and Steve Gould,
but also those I never had the pleasure of meeting, particularly the
late Dolf Seilacher. I just hope they would have approved of my
account of their research, brief though it is, even though perhaps they
might not have agreed with all my conclusions.
This article is distributed under the terms of the Creative Commons
Attribution 4.0 International License (http://creativecommons.org/
licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to
the original author(s) and the source, provide a link to the Creative
Commons license, and indicate if changes were made.
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