What bugged the Dinosaurs? Insects, Disease, and Death in the Cretaceous

This is the latest of several books on amber by George and Roberta Poinar and specifically looks at Cretaceous ambers (Lebanese, Burmese and Canadian) and what the inclusions can reveal about past ecology, particularly diseases. It is well illustrated (16 colour plates of amber specimens and 38 black and white figures, including line drawing reconstructions) and there are 23 chapters and three appendices that can be broadly broken down into three main areas: the feeding habits and ecology of insects, dinosaurs and plants; the vectors of disease; and climaxing with diseases contributing to the extinction of the dinosaurs. But it is a chimera (to coin a word commonly used in one chapter) of fact and fiction. When reading this book, it is wise to keep the following caveat from the preface in the back of your mind: "Some of what we say will be deemed erroneous and discarded, and some will fit and remain."

Most chapters start with a descriptive imaginative scene of an event that may have been played out around 100 million years ago, such as carnivorous dinosaurs hunting down diseased ornithopod dinosaurs, then becoming ill themselves from eating the infected flesh, through to "protobees" collecting pollen from flowers to feed their young.

In the main text, the Poinars excel at using modern analogues, such as particular disease-spreading insects and inferring that they did the same in the past. Unfortunately, some of this is presented as fact when there is no supporting fossil evidence, and on several occasions it is stated that dinosaurs "certainly" and "undoubtedly" fed on particular food types (for example, "ripped open rotting logs to collect the large juicy larvae of lucanid, oedomerid and longhorn beetles"), when of course this is pure speculation. Once I realised that some of their supposed facts are not supported by evidence, this ruined the book for me as I then began to seriously doubt most of their bold claims.

There are some irritating throwaway remarks that have not been thought through. For instance, it is suggested that there were four times as many insect families in the Cretaceous than today, and that there are only a few known Cretaceous fossil insect sites. This would imply that the majority of insect families in the Cretaceous are extinct; however, of the insect families recorded from the Cretaceous (listed in Appendix A) only 30 per cent are extinct. It also suggests that the authors have neglected to take into account the numerous Cretaceous non-amber fossil insect localities in Europe and Asia that have yielded thousands of specimens that have been well studied by Russian scientists, most of which can be placed in living families.

Additionally, the reference list is missing many good papers on Burmese amber, particularly by Russian and other American scientists. For instance, there is discussion about "protobees", yet Antropov's excellent paper (published in 2000) on Burmese amber digger wasps (closely related to bees) showing evidence of social behaviour (nine females found in one piece of amber) is not mentioned once.

Towards the end of the book is the best and most enjoyable chapter, "The discovery of Cretaceous diseases", which explains how the Poinars discovered sand flies and biting midges in Burmese amber (100 million years old) that contain Leishmania-like pathogens and viruses. Here, finally, is convincing fossil evidence to support some of their claims. If I had read this chapter early on in the book maybe I would have been less sceptical about the rest. So did insect-borne diseases contribute to the extinction of the dinosaurs? I'm not convinced. However, it is likely that some diseases were present that could have adversely affected their health.

The layman will find this an enjoyable book to read as it does trigger the imagination, but it should not be taken too seriously, and I do worry about some of the book's fiction appearing as fact in future texts, on the web and in documentaries.