Scientists were surprised by who actually first colonized land on Earth

An international team of scientists has for the first time fully reconstructed the evolutionary tree of modern myriapods and concluded that these arthropods appeared on land approximately 460 million years ago. This means they began colonizing terrestrial ecosystems more than 80 million years before vertebrate animals. The study was published in the journal Current Biology.

Today, myriapods are typically associated with inconspicuous inhabitants of forest litter that feed on dead plant remains. However, they were among the very first animals to successfully adapt to life on land.

For the study, scientists analyzed the DNA of 82 myriapod species and compared the obtained data with information from 29 fossil finds. Particularly significant was the examination of two extremely rare groups of myriapods whose position on the evolutionary tree had remained a mystery for over a hundred years.

To obtain the necessary specimens, researchers had to organize expeditions to Mexico and the Canary Islands. Some of the sought-after myriapods reach only about a centimeter in length and spend nearly their entire lives underground.

Genetic analysis made it possible to definitively determine the kinship relationships of these enigmatic animals and reconstruct the history of the entire group. It turned out that some myriapod lineages arose significantly earlier than previously assumed.

According to the authors' estimates, the first myriapods appeared approximately 460 million years ago — roughly 35 million years earlier than the oldest known fossil representatives of the group.

During that period, Earth looked completely different. There were no trees, no flowering plants, and no vertebrate animals on land. Myriapods fed on decomposing mosses, slime formations, and other organic remains, participating in the recycling of matter in the first terrestrial ecosystems.

The study also helped establish the timing of the emergence of one of the most unusual features of myriapods — chemical defense. Many modern species are capable of secreting toxic substances that repel predators.

According to the authors, the new study not only filled one of the last gaps in the evolutionary history of myriapods but also provided a better understanding of how Earth's first terrestrial ecosystems formed, paving the way for the emergence of more complex forms of life.