The question ‘what was the animal that produced conodonts?’ has perplexed scientists ever since details of these tiny phosphatic ‘teeth-like’ microfossils were published by Christian Pander in 1856. Some have even suggested that they were not produced by animals at all, but by plants. This contribution by Simon Knell tells the fascinating story from the early days of discovery up to the present, when conodont affinities continue to stimulate debate amongst the scientific community.
Those hoping for a complete review of the history of conodont studies will be disappointed, but Knell never set out to provide this. The palaeobiology of the conodont animal has been the work of relatively few conodont workers privileged enough to work on such exceptionally preserved specimens. Other less-fortunate scientists working on disarticulate specimens have also entered the argument, but it is the evolution of thinking about the nature of the conodont animal that has shaped the direction of this book. It is therefore of great interest to anyone interested in the mechanisms of scientific discovery, not just those that have devoted their lifetimes to studying conodonts.
Details of personal relationships, research groups, discoveries, conference presentations and arguments emerge as the author skilfully tells the story of research and discovery from the direction of various different research schools ranging from those in Chicago, Washington DC, Missouri, Ohio and Iowa in the USA to Marburg and finally the British School. It is also interesting to see the influence of workers seemingly isolated geographically and not part of large research groups.
The initial chapters set the scene, outlining early debates on the affinities of conodonts with the worm versus fish arguments coming to the fore. Following chapters show how the science developed as the discovery of bedding-plane assemblages and fused clusters led to debates on what defines a species when disarticulated remains are all that are offered by the fossil record for interpretation. For over 150 years, discussions and arguments on affinities continued with an incredible 53 different affinities suggested, some more credible than others. The development of new techniques for analysing conodont hard tissues – acid digestion, scanning electron microscopy and histological studies – are also shown to have had an enormous impact on the understanding of conodont palaeobiology. Later chapters cover the discovery and study of soft tissues erroneously interpreted as belonging to the conodont animal, such as Scott and Melton's conodont-eating animal from Bear Gulch or Conway Morris's Cambrian Odontogriphus.
The final chapters cover the eureka moment of discovery of preserved soft tissue in a museum collection and subsequent discoveries in the field of more ‘conodont animals’. The book ends with questions such as ‘are they teeth?’ and ‘are they vertebrates?’ seemingly answered. Knell aimed to show, through time, what the workers believed the animal to be, whether this was correct or not and in the introduction, aims to distance himself from any particular school or belief.
If I had one criticism of this book it would be that at the end it seems to come down too heavily on the ‘conodonts are vertebrates’ side of the argument, one that in the light of subsequently published research (Murdock et al. 2013) may again be in the balance. Reference is made fleetingly to alternative opinions on the vertebrate origins and an out of date ‘provisional’ list of authors gleaned from a newsletter article is included despite the final version of that paper being mentioned in the notes as being published. Knell states that this paper (full details not stated but it is Blieck et al. 2010) is a ‘manifesto for political change rather than a scientific argument’ and that may partly be true. However, more than a passing mention of the counter arguments would have made a stronger finish than the Afterword Chapter that, to me, slightly dilutes the picture that Knell has so beautifully painted of the enigma that is the conodont animal.
