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What Bugged the Dinosaurs?

What Bugged the Dinosaurs?: Insects, Disease, and Death in the Cretaceous

Copyright Date: 2008
Pages: 296
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  • Book Info
    What Bugged the Dinosaurs?
    Book Description:

    Millions of years ago in the Cretaceous period, the mighty Tyrannosaurus rex--with its dagger-like teeth for tearing its prey to ribbons--was undoubtedly the fiercest carnivore to roam the Earth. Yet asWhat Bugged the Dinosaurs?reveals, T. rex was not the only killer. George and Roberta Poinar show how insects--from biting sand flies to disease-causing parasites--dominated life on the planet and played a significant role in the life and death of the dinosaurs.

    The Poinars bring the age of the dinosaurs marvelously to life. Analyzing exotic insects fossilized in Cretaceous amber at three major deposits in Lebanon, Burma, and Canada, they reconstruct the complex ecology of a hostile prehistoric world inhabited by voracious swarms of insects. The Poinars draw upon tantalizing new evidence from their amazing discoveries of disease-producing vertebrate pathogens in Cretaceous blood-sucking flies, as well as intestinal worms and protozoa found in fossilized dinosaur excrement, to provide a unique view of how insects infected with malaria, leishmania, and other pathogens, together with intestinal parasites, could have devastated dinosaur populations.

    A scientific adventure story from the authors whose research inspiredJurassic Park,What Bugged the Dinosaurs?? offers compelling evidence of how insects directly and indirectly contributed to the dinosaurs' demise.

    eISBN: 978-1-4008-3569-0
    Subjects: Biological Sciences, Ecology & Evolutionary Biology, Zoology

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
  3. Preface
    (pp. ix-x)
  4. Acknowledgments
    (pp. xi-xiv)
  5. Introduction
    (pp. 1-6)

    If an autopsy had been made on this ornithopod, it would have revealed many parasites and pathogens inhabiting the tissues. Some, like amoebic dysentery, malaria, and ascarid roundworms, would have caused lesions in the gut, liver abscesses, and distorted blood cells. But the actual cause of our dinosaur’s death would have been listed as leishmaniasis, a protozoan disease. Just like the other members of the herd, he was the victim of an emerging pathogen that was decimating the Cretaceous world. Some 100 million years ago, some of these microorganisms developed novel relationships with biting flies, when the flies’ previously harmless...

  6. 1. Fossils: A Time Capsule
    (pp. 7-16)

    These events would be uncovered millions of years later when the victims would be revealed to us as fossils frozen in rock and entombed in amber from an extinct araucarian forest. It is from such fossils that we will attempt to unravel a story of struggle, terror, and disease in the Cretaceous, one that involves insects, dinosaurs, and their food plants.

    Many people have asked us why we have such an inordinate fascination with fossils, particularly those in amber. The answer is complex but several reasons stand out. Fossils are intriguing because they put human time into perspective. Few of...

  7. 2. The Cretaceous: A Time of Change
    (pp. 17-36)

    The sun rose and set over 29 billion times during the Cretaceous. Each succeeding dawn and nightfall saw the birth and death of billions of organisms, and in every passing millennium, species arose or became extinct. Dramatic physical and biological changes molded the evolution of insects, plants, and dinosaurs during that period in the planet’s history. Differences in insect taxa are evident in the amber fossils found in Lebanon in the Early, Burma in the mid, and Canada in the Late Cretaceous. Other fossil deposits tell us that similar changes also occurred in dinosaurs and plants.

    In the 25–30...

  8. 3. Herbivory
    (pp. 37-49)

    Green plants are the most important organisms in any terrestrial ecosystem and have been since they first evolved. In terms of diversity, they are second only to insects and represent about one quarter of the total known species. They capture the energy from the sun and convert it into the plant tissues that sustain all animals. Herbivores transfer that energy directly into their tissues when eating plants, and carnivores indirectly obtain the energy when feeding on herbivores. For this reason plants comprise the very basis of the food chain.

    There are many factors that determine where a particular insect or...

  9. 4. Dinosaurs Competing with Insects
    (pp. 50-54)

    From the habits of present day herbivorous insects, we can infer how they would have competed with dinosaurs. We know that nemonychid weevils, like the one found in Lebanese amber, feed on pollen in the male cones of kauri trees and presume that they had similar habits in the Early Cretaceous. And it is quite likely that this source of protein was sought after by dinosaurs, just as birds and lizards feed on pollen today.⁵⁶ The interfaces between insects and dinosaurs regarding conifer cones represent just one type of antagonism that would have occurred between these groups. Dinosaurs and insects...

  10. 5. Did Dinosaurs or Insects “Invent” Flowering Plants?
    (pp. 55-56)

    While relatively few angiosperms were established at the beginning of the Cretaceous, by the Late Cretaceous flowering plants accounted for possibly half of the plant diversity. With their amazingly rapid growth rates and relatively short reproduction periods, these plants were predestined for success. Encoded in their genetic makeup was the ability to radiate into a variety of habitats, from bogs and marshes to stone crannies, mountaintops, and tree branches.

    In his book on dinosaurs,⁵² Robert Bakker felt that plant-eating dinosaurs could have “invented” flowering plants. He concluded that in contrast to the Late Jurassic browsers that fed on foliage in...

  11. 6. Pollination
    (pp. 57-62)

    The most significant way insects aided the establishment and spread of flowering plants was by their pollination activities, something the dinosaurs were incapable of doing. Most of the early plants were wind and water pollinated, and neither dinosaurs nor insects took an active part in this process. However, this did not keep any number of insects, from beetles and thrips to flies and wasps, from feeding on pollen from cycads, cycadeoids, and conifers. Those ancient associations may have been strictly one-sided, with the insects just eating the pollen and leaving, but at the same time, some could have fortuitously transferred...

  12. 7. Blights and Diseases of Cretaceous Plants
    (pp. 63-71)

    The Cretaceous was a moldy world, not that much different from the tropical regions today. Fungi parasitized other fungi, and these in turn were parasitized by still others.³⁴⁵ Having lived in the tropics, we know what it is like to find masses of long gray filaments emerging from shoes left in the closet a few days, spots spreading over various parts of your skin, spores clogging your respiratory system, and delicate strands etching the surfaces of microscope lens. In fact, practically all of the microscopes in our West African laboratory were useless because of fungal-caused scratches on the lens surfaces...

  13. 8. The Cretaceous: Age of Chimeras and Other Oddities
    (pp. 72-78)

    I was astonished when I peered down the microscope lens and saw my first Cretaceous chimera. When studying insects in younger Dominican, Mexican, and Baltic amber, it was commonplace to place the fossil in a modern family and sometimes in an extant genus. But these mid-Cretaceous fossils opened up an exciting, strange new world with creatures bearing combinations of characters never before seen among the living. Besides instilling wonderment, trying to identify these enigmas kept me awake at night since according to established standards, they shouldn’t have existed at all. It made me realize that the current classification system has...

  14. 9. Sanitary Engineers of the Cretaceous
    (pp. 79-90)

    The world in the Cretaceous would have been a fetid mess without insects. Can you imagine putrefying dinosaur corpses littering the landscape, heaps of dung remaining for months on end, and dead vegetation taking forever to be recycled? Eventually microbes, earthworms, and other scavengers would have decomposed this waste material, but certainly without the assistance of insects, parts of the prehistoric world would have been almost uninhabitable for many animals.

    Dinosaurs, like a majority of animals today, voided solid waste. Certainly “waste” is a poor term since animal dung actually contains enough nutrients to nurture a wide range of smaller...

  15. 10. The Case for Entomophagy among Dinosaurs
    (pp. 91-101)

    In all probability, almost every dinosaur, even those considered vegetarians, were in actuality omnivores at some point in their lives, certainly when they were in the rapid growth stages and possibly also during periods of egg production. You may question how we arrived at that conclusion, but even today characterizing an animal as an herbivore, omnivore, or carnivore is an almost impossible task, so we assume the same held true for dinosaurs. Few vertebrates are truly one or the other. For example, mammals begin their lives dependent on a food source rich in protein, mother’s milk. Fruit- and nectar-eating birds...

  16. 11. Gorging on Dinosaurs
    (pp. 102-109)

    Fresh vertebrate blood is not exactly everyone’s ideal meal. But for a few animals such as leeches, vampire bats, and hematophagous insects, it represents haute cuisine. And even some humans, like the Masai of Kenya, are well known for surviving on a mixture of milk and blood drawn from cows and goats. But by far, the largest group of animals to develop this proclivity is bloodsucking insects, and they have truly perfected this habit because their very survival has depended on this sanguinary diet since the Cretaceous.

    Even when we slather ourselves with repellants, bloodsucking insects can make our lives...

  17. 12. Biting Midges
    (pp. 110-115)

    Biting midges (ceratopogonids) were just one of many insects that fed on vertebrate blood in the late Mesozoic. From amber, we know they shared this habit with sand flies and corethrellid flies,³³⁸ as well as other groups found in different types of fossil deposits (color plate 11C). Some people may be familiar with biting midges as the minute “no-see-ums” or “punkies” that deliver painful bites. You may not notice them coming or going—but you definitely know when they begin to feed! These ancient flies were quite common and widely distributed throughout the Cretaceous.¹³,¹⁵⁶ Their evolutionary success is due to...

  18. 13. Sand Flies
    (pp. 116-121)

    Bloodletting is a medical practice used by humans for well over two thousand years. The procedure, known as phlebotomy, involved puncturing one of the larger veins and draining blood into a container. This process is reminiscent of the modus operandi of phlebotomine sand flies that have used the method for at least 100 million years. Sand flies are one of the earliest groups of biting flies that developed a taste for vertebrate blood. They had probably evolved by the Jurassic, and early forms may have used their mandibles to obtain sap from primitive plants, much as some sand flies penetrate...

  19. 14. Mosquitoes
    (pp. 122-126)

    Mosquitoes are uncommon as fossils, even in recent amber from the Dominican Republic,¹⁹⁰ and only a single uncontested specimen has been described from the entire Cretaceous¹⁹¹ (color plate 11D). Another possible representative from Early Cretaceous deposits of England³⁵ suggests that these bloodsuckers occurred throughout the period.

    By the Late Cretaceous, their hosts would have included mammals, birds, reptiles, and amphibians, as well as dinosaurs. Primitive species could have developed in salt or brackish water and preyed on vertebrates in the same habitat, similar to those that now attack sea turtles in Florida and South America.¹⁹²,¹⁹³ The bloodsuckers seemingly arrive out...

  20. 15. Blackflies
    (pp. 127-130)

    Did millions upon millions of blackflies soar over Cretaceous fens and fern grottos, clogging the nasal passages of feeding dinosaurs? Would their appearance cause dinosaurs to stampede, tripping over rocks, breaking legs, or plunging off cliffs in a frantic rush to escape the torturers? Were toxic substances in insect saliva causing allergic reactions and blood poisoning? Could masses of these noxious flies cover a dinosaur’s skin and remove so much blood that it would expire from exsanguination? All of the above are known to occur today when blackflies attack grazing bovines on the plains of western Canada.²⁰⁴,²⁰⁵ These insects are...

  21. 16. Horseflies and Deerflies
    (pp. 131-134)

    Horseflies and their smaller cousins deerflies of the family Tabanidae were widespread throughout the Cretaceous and because they now feed on both warm- and cold-blooded animals,²¹⁰²¹³ they certainly took blood from dinosaurs (fig. 22). Their painful bites and persistence behavior would have greatly irritated the huge reptiles, just as they do many animals today, from reptiles to humans. At least four species of horseflies are known to prey on crocodiles and anacondas in the Amazon.²¹⁴ The onslaught begins with the flies circling rapidly around the victim before alighting. Feasting commences as soon as they land, and each species appears...

  22. 17. Fleas and Lice
    (pp. 135-140)

    Parents cringe when their child brings a note from school informing them that a lice infection has been detected in the classroom and their child needs to be treated. And pet lovers know all about the astonishing jumping abilities of fleas and their painful, itching bites. Such pests have followed us into urban communities, and even with all our efforts to control them, still manage to plague us. Think how primitive man must have suffered!

    Where would these pests have occurred on dinosaurs? A reasonable location would be among the plumage of feathered dinosaurs. Fleas and lice thrive under the...

  23. 18. Ticks and Mites
    (pp. 141-146)

    While ticks and mites are not insects but arachnids related to spiders, both probably played important roles in the transmission of pathogens in the Cretaceous world. There are hard and soft varieties of ticks, and in spite of the difference in body shape, texture, and feeding habits, both sexes of all species require vertebrate blood for survival. After inserting a hollow tube, or hypostome, into the integument, blood is pumped directly into their stomachs. Ticks are very patient and will remain on vegetation for days, weeks, or even months until a host passes close enough for attachment and feeding. A...

  24. 19. Parasitic Worms
    (pp. 147-156)

    Parasitic worms, also known as helminths, are widespread in all vertebrate groups today. The eggs of these parasites have been recovered from prehistoric and fossilized coprolites of many animals, including dinosaurs.¹³⁵ So we already know that dinosaurs harbored both stomach worms (ascarids) and trematodes in their gut. And if nematodes and trematodes were present in the Cretaceous, we can assume that tapeworms and spiny-headed worms were also there. What, then, was the effect of these parasites?

    There are many groups of nematodes besides ascarids that had the potential to infect dinosaurs, including types that live in the alimentary tract, blood,...

  25. 20. The Discovery of Cretaceous Diseases
    (pp. 157-170)

    Long before our search for Cretaceous diseases began, events as described above took place in a Burmese forest 100 million years ago. The last few seconds in the life of this fly were extremely important, for they would set the stage for the very first discovery of a Cretaceous insect-vectored disease.

    One of many theories presented on the demise of the dinosaurs states that they succumbed to diseases.²⁵ While intriguing, there was no evidence that terrestrial vertebrate pathogens existed in the Mesozoic—until recently. This is the story of how they were discovered.

    We have been interested in the history...

  26. 21. Diseases and the Evolution of Pathogens
    (pp. 171-184)

    One of the basic premises of this book is that Cretaceous insects transmitted pathogens that either directly or indirectly affected dinosaurs. The results were not only dinosaur disease and mortality but also the destruction of dinosaur food plants. We feel that most, if not all, present-day vector-pathogen associations were already established or arose at some point in the Cretaceous, even though different genera and species of hosts and vectors were involved.

    The origins and coevolution of pathogens with their vectors and plant or animal hosts are complex. When the first dinosaurs walked the earth, they already came with pathogens carried...

  27. 22. Insects: The Ultimate Survivors
    (pp. 185-191)

    Insects have been around for more than 400 million years. Dinosaurs (non-avian) only lasted 180 million. What determines how long families, genera, and species survive? When biological and physical events impact a species so that the death rate continuously exceeds the birth rate, that life form has begun a downward spiral towards extinction. Ultimately a low population threshold is reached where recovery is impossible and the fate of the species is sealed. That loss has a ripple effect throughout the ecosystem, the severity of which depends on the importance of the species. Demise of a keystone species invokes the greatest...

  28. 23. Extinctions and the K/T Boundary
    (pp. 192-202)

    Extinctions vary in intensity from normal low-level background to major events where some 50% of the total species of plants and animals disappear. Of the many global restructurings that have been detected, only five qualify as mass extinctions. The best publicized occurred around the Cretaceous-Tertiary (K/T) boundary some 65.5 mya and coincides with the demise of the dinosaurs. The many theories that have been proposed for the cause of these extinctions have broadly divided the scientific community into two camps, the catastrophists and the gradualists, and pivot around the central issue of time span. How fast did the detected extinctions...

  29. Appendix A: Cretaceous Hexapoda
    (pp. 203-218)
  30. Appendix B: Key Factors Contributing to the Survival of Terrestrial Animals
    (pp. 219-220)
  31. Appendix C: Problems with Evaluating the Fossil Record and Extinctions
    (pp. 221-224)
  32. References
    (pp. 225-252)
  33. Index
    (pp. 253-264)