New Book claims Biting Insects and Bugs helped in Dinosaur Demise

The trend for putting forward a new spin on the mass extinction theories continues unabated with the publication of a new book entitled “What Bugged the Dinosaurs? Insects, Disease and Death in the Cretaceous”  published by Princeton University Press.

When it comes to mass extinctions the events that took place 65 million years ago leading to the eradication of the dinosaurs, pterosaurs, marine reptiles and about 65% of all life on Earth, certainly attracts the most attention.

Recently, the Chicxulub impact theory first put forward in 1980 by the father and son team of Luis and Walter Alvarez was challenged by new evidence of volcanic activity in India – The Deccan Traps effect.

To read article on Deccan Traps: Blame the Deccan Traps

Now this book postulates that changing ecosystems and the rise of biting disease carrying insects could have played a significant role in bringing down the dinosaurs.

An important contributor to the extinction of the dinosaurs, could have been the rise and evolution of insects, especially the slow-but-overwhelming threat posed by new disease carriers. And the evidence for this emerging threat and the diversification of insects and arthropods has been captured in fossilised tree sap – amber.

Co-author of this new book George Poiner Jr. (courtesy professor of zoology at Oregon State University), stated:

“There are serious problems with the sudden impact theories of dinosaur extinction, not the least of which is that dinosaurs declined and disappeared over a period of hundreds of thousands, or even millions of years.  That time frame is just not consistent with the effects of an asteroid impact. But competition with insects, emerging new diseases and the spread of flowering plants over very long periods of time is perfectly compatible with everything we know about dinosaur extinction.”

George and his co-author, his wife, Roberta have spent many years studying the micro-fossils and preserved insect and arthropod remains from the late Cretaceous.  They theorise that although there were dramatic geological and climatic changes at the famous “K-T Boundary”, these events on their own do not explain what may have been a slow and gradual demise of the dinosauria.

However, perhaps with animal populations under severe stress from such events, they may have been weakened to such an extent that diseases and parasites spread by biting/ sucking insects and arthropods could have finally seen them off.

“We don’t suggest that the appearance of biting insects and the spread of disease are the only things that relate to dinosaur extinction,” George Poinar said. “Other geologic and catastrophic events certainly played a role. But by themselves, such events do not explain a process that in reality took a very, very long time, perhaps millions of years. Insects and diseases do provide that explanation.”

George and his wife, Roberta have published previous works detailing their studies into the ecosystems and fauna revealed by fossil amber.

“During the Late Cretaceous Period, the associations between insects, microbes and disease transmission were just emerging,” he commented. “We found in the gut of one biting insect, preserved in amber from that era, the pathogen that causes leishmania — a serious disease still today, one that can infect both reptiles and humans. In another biting insect, we discovered organisms that cause malaria, a type that infects birds and lizards today.”

Fossil Tick Found in Amber from Burma

Picture Credit: Oregon State University

“In dinosaur feces, we found nematodes, trematodes and even protozoa that could have caused dysentery and other abdominal disturbances. The infective stages of these intestinal parasites are carried by filth-visiting insects.”

In the lush, tropical Late Cretaceous insects, lice and other parasites would have thrived and perhaps these animals caused disease epidemics that helped weaken the populations of mega fauna.

The Poinars cite the case of bird malaria which when introduced into Hawaii killed off many of the native honey creepers on the islands.  Although from our perspective this is a case of isolated animal communities being exposed to new pathogens, new diseases that they had not been exposed to before, with the consequence of them not being able to build up any immunity within the species.  Dinosaurs co-existed for millions of years with parasites and biting insects – the fossil record of Mesozoic animals bares testament to this.

The authors suggest that in addition to the parasitic effects on the dinosaurs, the ecosystem was being radically altered due to the rapid expansion of the angiosperms (flowering plants); in part due to the pollination activities of insects.  The flowering plants do seem to have been an evolutionary success story by the end of the Mesozoic with cycads, gingkoes and other gymnosperms being upstaged by their more colourful plant competitors.  But again this process would have been quite gradual, giving herbivores the opportunity to adapt to and exploit these new food sources.  For example, some scientists have speculated that the Pachycephalosaurs may even have specialised as nibblers and browsers of flowering plants and bushes just like many African gazelles do today.

“Insects have exerted a tremendous impact on the entire ecology of the Earth, certainly shaping the evolution and causing the extinction of terrestrial organisms,” the Poinars wrote in their book. “The largest of the land animals, the dinosaurs, would have been locked in a life-or-death struggle with them for survival.”  Although a rather dramatic statement, perhaps more akin to helping to sell their book, a weakened population could have further declined due to the activities of parasites and other pathogens brought on by the increase in insects and arthropods.  But again, all organisms compete with each other and it is hard to believe that all the large terrestrial fauna, including the Pterosaurs could have succumbed to pests and diseases.

“We can’t say for certain that insects are the smoking gun, but we believe they were an extremely significant force in the decline of the dinosaurs,” Poinar said. “Our research with amber shows that there were evolving, disease-carrying vectors in the Cretaceous, and that at least some of the pathogens they carried infected reptiles. This clearly fills in some gaps regarding dinosaur extinctions.”

Insects have been connected to the demise of the dinosaurs on numerous occasions.  In our extensive library we have book entitled “Before the Ark” published by the British Broadcasting Corporation (BBC) in 1975.  The authors were Dr Alan Charig, curator of Fossil Amphibians, Reptiles and Birds at the London Natural History museum and Brenda Horsfield – a television producer.  The book accompanied a television documentary series on palaeontology.  In Chapter 13, entitled “Fall of the Dinosaurs” the then, current theories about dinosaur extinction were discussed.

One idea put forward was that the emergence and rapid expansion of the order Lepidoptera (moths and butterflies), put paid to the dinosaurs.  The larval stages, the caterpillars with their voracious appetites consumed a lot of the vegetation leading to the sudden collapse of food webs and the extinction of the mega fauna at the top of these food webs.  A caterpillar caused defoliated eco-system is a bit hard to digest, (no pun intended), after all why did the marine reptiles and ammonites also disappear.  The birds would certainly have spotted a new food source and helped reduce caterpillar numbers, unless of course the larvae had already developed complicated bird scaring defences like the modern hawk moths or become unpalatable such as the Cinnabar moths of the UK and Europe.

Birds had diversified and filled many ecological niches, surely they would have been quick to exploit this new food source and anyway the Dr Charig and Ms Horsfield go on to cast considerable doubt as to the validity of this theory, for example mass defoliation on such a scale would have left some sort of evidence within the fossil record.  Palynomorphs – organic walled micro fossils such as plant spores and pollen do indicate a dramatic change in vegetation at the K-T Boundary, the “fern spike”, but this adds credence to the impact of a huge environmental disaster such as asteroid impact or massive volcanic activity.  The ferns are often the first plant group to recover, hence the large increase in fern spores making up the micro fossil record from around 65 million years ago.

To read more about the fern spike: Humble Ferns – Evidence to Support the Impact Theory

Certainly, this new book will interest many, the theories put forward will fuel further debate and provide much food for thought.  Indeed, as the human race experiences its own climate change and environmental problems, perhaps the rising seas, flooding low-lying land will give rise to new epidemics of diseases such as malaria as mosquitoes swarm and thrive in the newly created marshlands.

It might not just be dinosaurs that end up being “bugged” out of existence.

The team at Everything Dinosaur are grateful for the information supplied by Oregon State University (Jan 4 2008) in the writing of this article.

To visit Everything Dinosaur website: Everything Dinosaur Homepage

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