Did Insects Kill the Dinosaurs?

Ponca City, We Love You writes "Asteroid impacts, massive volcanic flows, and now biting, disease-carrying insects have been put forward as an important contributor to the demise of the dinosaurs. In the Late Cretaceous the world was covered with warm-temperate to tropical areas that swarmed with blood-sucking insects. A theory explored by researchers at Oregon State suggests these bugs carried leishmania, malaria, intestinal parasites, arboviruses and other pathogens. Repeated epidemics may have slowly-but-surely worn down dinosaur populations while ticks, mites, lice and biting flies tormented and weakened them. 'After many millions of years of evolution, mammals, birds and reptiles have evolved some resistance to these diseases,' says Researcher George Poinar. 'But back in the Cretaceous, these diseases were new and invasive, and vertebrates had little or no natural or acquired immunity to them.' The confluence of new insect-spread diseases, loss of traditional food sources, and competition for plants by insect pests could all have provided a lingering, debilitating condition that dinosaurs were ultimately unable to overcome."

Comments

Re:extremely suspect

[flyingsquid]

The end-Cretaceous mass extinction did not just target the dinosaurs. It resulted in the extinction of dinosaurs, pterosaurs, the vast majority of birds, many mammals and lizards, a few turtles and crocodilians, frewshwater sharks, freshwater clams, large marine reptiles (mosasaurs and plesiosaurs), ammonites (shelled cephalopods similar to the modern chambered nautilus), marine plankton, many species of plants... and ironically enough, some insects. The insect fossil record isn't good enough to look at extinction patterns, but if you look at fossil leaves, a number of distinctive feeding traces disappear 65 million years ago, at the same time as the dinosaurs, indicating that whatever plant-eating insects made them went extinct.

In short, it is unlikely that biting insects could be responsible for all this chaos. The extinction was simultaneous, worldwide, and (in geological terms) instantaneous, it hit animals and plants, and it hit organisms on land and in the sea. Now, it turns out, probably not coincidentally, that at the same time all of this happens, a huge asteroid or comet impact- one of the biggest in the past half-billion years- takes place in the Yucatan, blasting dust into the stratosphere, sending tidal waves across Texas, and probably igniting much of North America in the process. An asteroid impact is probably capable of causing an extinction like this. Its doubtful that gnats, mites, and mosquitos could.