Fungus may have killed the dinosaurs!!!

Fungal virulence, vertebrate endothermy, and dinosaur extinction: is there a connection?

Casadevall A.

Abstract

Fungi are relatively rare causes of life-threatening systemic disease in immunologically intact mammals despite being frequent pathogens in insects, amphibians, and plants. Given that virulence is a complex trait, the capacity of certain soil fungi to infect, persist, and cause disease in animals despite no apparent requirement for animal hosts in replication or survival presents a paradox. In recent years studies with amoeba, slime molds, and worms have led to the proposal that interactions between fungi and other environmental microbes, including predators, select for characteristics that are also suitable for survival in animal hosts. Given that most fungal species grow best at ambient temperatures, the high body temperature of endothermic animals must provide a thermal barrier for protection against infection with a large number of fungi. Fungal disease is relatively common in birds but most are caused by only a few thermotolerant species. The relative resistance of endothermic vertebrates to fungal diseases is likely a result of higher body temperatures combined with immune defenses. Protection against fungal diseases could have been a powerful selective mechanism for endothermy in certain vertebrates. Deforestation and proliferation of fungal spores at cretaceous-tertiary boundary suggests that fungal diseases could have contributed to the demise of dinosaurs and the flourishing of mammalian species.

Fungal Genet Biol. 2005 Feb;42(2):98-106. Epub 2005 Jan 5.

Why?

Today's article is a truly amazing idea! Everyone pretty much believes that a meteorite struck the Earth a long time ago and this caused the extinction of the dinosaurs. The dirt thrown into the air darkened the sky for years and plants could not grow and plant eaters can't flourish with no plants and predators can't live with dwindling food supplies. The author, who I heard speak some years ago, proposes that when the dirt was thrown in the air the normal fungus in the dirt was also thrown and ultimately breathed in by dinosaurs. A word about body temperature, mammals maintain a body temperature of 98.6 F (37 C) no matter the temperature outside. Reptiles, amphibians, and insects do not regulate their body temperature and that is why they are generally restricted to warmer climates or warmer seasons. Fungus can't grow at mammalian body temperature, but it can grow at a slightly reduced normal temperature. Connecting all that, fungus in the air that was breathed in by dinosaurs, who have the perfect temperature for fungal growth, grew inside of the dinosaurs!

The fungal infection killed the dinosaurs! Mammals with their higher body temperature survived and become conquerors of the Earth! Those conquerors went on to produce the greatest human ever born: Lee Marvin.