Scientists from Cornell University think it’s possible that dinosaurs or dinosaur-like creatures could exist on planets around other stars. They studied how Earth looked over the past 540 million years and found clues that might help in the search for life on other worlds.

The dinosaurs lived on Earth around 100 to 300 million years ago. During that time, oxygen levels in our atmosphere were higher than they are today – up to 35% oxygen compared to 21% now. The researchers created computer models of what Earth’s atmosphere would have looked like back then. They modeled how light from the sun interacts with different gas mixtures in the air. Some colors of light get absorbed, while others pass through. This leaves a unique “sunlight fingerprint” that reveals what gases are present.

The sunlight fingerprint from an Earth-like planet with higher oxygen, similar to dinosaur times, would stand out more than today’s version. Certain pairs of gases, like oxygen and methane or ozone and methane, produced stronger signals in the models. This means telescope instruments might be able to spot signs of these gases on a distant planet more easily.

Finding the right atmospheric mixture could be a clue that complex life exists there too, perhaps something as big as the dinosaurs rather than just microbes. The dinosaurs thrived when oxygen levels allowed forest fires but prevented them from going out. Their era between 245 to 66 million years ago is known as the time of major plant and animal diversification on Earth.

So while evolution may unfold differently elsewhere, the Cornell models provide templates for what habitable planets with different oxygen levels could look like to our telescopes. So far, about 40 rocky planets have been found in their stars’ “habitable zones” where liquid water and possibly life could exist. The James Webb Space Telescope may soon be able to analyze the atmosphere of some exoplanets, if they have one at all. But scientists need to know what fingerprints to look for.

These new models identify oxygen-rich planets similar to Earth’s past as especially promising targets. Although we’ll probably never see actual dinosaurs, it’s possible that on a planet with 30% oxygen, life would not be limited to microbes but larger, more complex creatures. If such places exist, this work helps narrow down where those creatures might be living today. Even if no dinosaurs roam the cosmos, an oxygen-primed planet’s sunlight fingerprint should stand out starkly against the stars. One day, we may find planets with atmospheres better suited for advanced life than our own – and who knows what marvels they could hold?


James Dean, Jurassic worlds might be easier to spot than modern Earth (Cornell University) | R C Payne, L Kaltenegger, Oxygen bounty for Earth-like exoplanets: spectra of Earth through the Phanerozoic, Monthly Notices of the Royal Astronomical Society: Letters, Volume 527, Issue 1, January 2024, Pages L151–L155,

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