This post continues my discussion of the film “Extinction and rebirth.”
The exploding lava, from western Siberia, with its accompanying carbon dioxide warmed the planet enough that the Siberian problem became global. Many plants died because of the volcanic activity, and the planet warmed enough that methane hydrates began to melt from deep below the Panthalassa ocean releasing huge amounts of methane gas. The methane gas caused the Earth to become hotter than it has been in the past 600 million years, and the methane gas also combined with oxygen in the atmosphere to further reduce oxygen. 96% of all marine species, and 70% of all terrestrial vertebrate species became extinct. How did life adapt to less oxygen?
Comparison of the air sac system of birds and a dinosaur, National Science Foundation, public domain.
Many terrestrial vertebrates evolved to have air sacs. Birds today use this unique air sac/lung respiration system for very high altitude flight, but it began in that long distant time in response to a low oxygen atmosphere. Dinosaur fossils show that same air sac/lung respiration system, and they began evolving in the Triassic when oxygen levels were still quite low. It is thought that early mammals coped with the low oxygen levels by remaining small, having smaller rib cages to allow more room for lung expansion, and evolving a womb/placenta system to protect the young longer than it could in an egg case. These adaptations allowed both to survive the 4th mass extinction at the Triassic/Jurassic boundary, but the non-avian dinosaurs perished during the 5th mass extinction caused by the asteroid that hit Earth 66 million years ago. Add an opposable thumb, a lot of luck, a few million years, and the next thing you know someone is typing on a keyboard about a film on mass extinction & rebirth while worrying about current events.
Life finds a way then and now. We will find a way through this Pandemic; we will survive. Wear your mask, wash your hands, stay socially distant, and vote!
Thank you,
Patti Dittoe