NEW YORK, Jan 5 (Bernama) — Dinosaurs became extinct from the effects of a massive asteroid hitting Earth 65 million years ago, scientists have long maintained.
However, a new theory has suggested that the mightiest creatures may have succumbed to attacks by disease-carrying insects.
According to the theory profounded by Professor George Poinar of the Oregon State University and his wife Roberta, the demise of the dinosaurs and the rise and evolution of the insects, particularly the biting and disease-carriers, are linked to each other.
“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. We also don’t suggest that the appearance of biting insects and the spread of disease are the only things that relate to dinosaur extinction.
“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,” the Press Trust of India (PTI) quoted Prof Poinar as saying in the ‘ScienceDaily.
The couple have entailed their concept in a recently released book ‘What Bugged the Dinosaurs? Insects, Disease and Death in the Cretaceous’.
In their book, the authors have argued that insects provided a plausible and effective explanation for the slow, inexorable decline and eventual extinction of dinosaurs over thousands of years. This period is known as the famous ‘K-T Boundary’ about 65 million years ago.
There is evidence that some catastrophic events, such as a major asteroid or lava flows, also occurred at this time — but “these provide no complete explanation for the gradual decline of dinosaur populations, and even how some dinosaurs survived for thousands of years after the K-T Boundary”.
Insects and disease, on the other hand, may have been a lot slower, but ultimately finished the job, according to the researchers.
Poinar and Roberta claimed to have based their theory on a study of the plant and animal life forms found preserved in amber millions of years ago — amber has the unique ability to trap very small animals and display them neatly.
This phenomenon has been invaluable in scientific and ecological research, and among other things, formed the scientific premise for the movie Jurassic Park, for the “dinosaur DNA” found in mosquitoes.
“During the late Cretaceous Period, the associations between insects, microbes and disease transmission were just emerging. 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. 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,” Prof. Poinar said.
In the Late Cretaceous, Prof Poinar explained that the world was covered with warm-temperate to tropical areas that swarmed with blood-sucking insects carrying leishmania, malaria, intestinal parasites and other pathogens, and caused repeated epidemics that slowly wore down dinosaur populations.
“Smaller and separated populations of dinosaurs could have been repeatedly wiped out, just like when bird malaria was introduced into Hawaii, it killed off many of the honeycreepers. After many millions of years of evolution, mammals, birds and reptiles have evolved some resistance to these diseases.
“But back in the Cretaceous, these diseases were new and invasive, and vertebrates had little or no natural or acquired immunity to them. Massive outbreaks causing death and localised extinctions would have occurred,” Prof. Poinar said.
In similar fashion, the researchers have suggested that the insects would have played a major role in changing the nature of plant life on Earth — the fundamental basis for all dinosaur life, whether herbivore, omnivore or carnivore.
“As the dinosaurs were declining, their traditional food items such as seed ferns, cycads, gingkoes and other gymnosperms were largely being displaced by flowering plants, which insects helped spread by their pollination activities.
“These plants would have spread to dominate the landscape. Also, insects could have spread plant diseases that destroyed large tracts of vegetation, and the insects could have been major competitors for the available plant food supply.
“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 largest of the land animals, the dinosaurs, would have been locked in a life-or-death struggle with them for survival,” according to the authors.