Alien 'dinosaurs' could be lurking on distant planets, scientists suggest

According to numerous accounts, modern civilizations emerged only within the past few thousand years. And despite our self-proclaimed sophistication, it has only been about 60 or 70 years since we managed to launch objects into space. In the grand scheme of the 3.7 billion years of life on Earth, we represent a mere speck, accounting for just 0.000001% of the planet's biological history.

This may not be an isolated reality. Regardless of where life arises in the cosmos, it likely endures arduous evolutionary processes spanning millions or billions of years before attaining the futuristic depictions we see in movies. Therefore, if life does exist beyond Earth, a significant portion of it probably still exists in a comparable stage of development to our dinosaur-inhabited past.

Recent research aligns with this notion, suggesting that alien dinosaurs are not only a possibility on other planets but should actively be considered in our search for extraterrestrial life.

The study highlights that oxygen levels during our dinosaur era were exceptionally high, reaching 30% compared to the current 21%. This elevated level is believed to have contributed to the gigantic sizes of many prehistoric creatures, such as dragonflies with wingspans of 2.5 feet. Various other compounds may have also become less abundant or disappeared as the Earth's species evolved.

Drawing upon this crucial geological shift, the researchers advocate for examining planets with similar oxygen levels and even expanding our search to encompass other such "extinct" compounds. Theoretically, this approach should enhance our chances of discovering planets capable of harboring life, even large and complex ones resembling our dinosaurs.

Specifically, they emphasize the need to seek signs of a Phanerozoic stage – the eon spanning the past 541 million years, during which animal and plant life proliferated on Earth.

"The Phanerozoic represents only about the last 12% of Earth's history, but it encompasses nearly all of the time when life was more complex than microbes and sponges," explains lead author Rebecca Payne. "These faint chemical signatures are what you would look for elsewhere if you were searching for something more advanced than a single-celled organism. And who knows, maybe there are other dinosaurs waiting to be found out there."

The findings of this research have been published in Monthly Notices of the Royal Astronomical Society.