Onocleaceae is a small group of ferns with around five species spread across four different genera. These ferns are found in a wide range of places, from the cold north to the temperate zones. One interesting fact is that they are found in both Eurasia and North America, including Mexico. This wide distribution has caused some confusion among scientists about how to classify these ferns.

The main issue is that these ferns are found in separate areas, which makes it hard to study them all at once. To make things more complicated, scientists have different ideas about how many genera and species there are. This has led to a lot of debate and disagreement.

To solve this puzzle, scientists used a method called phylogenetic analysis. They looked at the DNA of 17 different parts of the ferns' plastids and one part of their nucleus. This helped them figure out that Onocleaceae has four main groups. One of these groups, called Pentarhizidium, is the oldest.

The study also found out that these ferns started to appear around the Late Cretaceous period. This was a time when dinosaurs still roamed the Earth. The different groups of Onocleaceae, like Matteuccia, Onoclea, Onocleopsis, and Pentarhizidium, started to form during the Paleogene and Neogene periods. These are the times when mammals began to dominate the Earth.

The ancestors of some of these ferns might have traveled to North America using land bridges that connected Asia and North America. This migration happened around the same time as a major climate event called the Paleocene-Eocene Thermal Maximum (PETM). This event caused a lot of changes in the environment, which might have helped these ferns spread out.

The study also suggests that the number of Onocleaceae species peaked during the late Neogene to Quaternary periods. This is a time when many modern plants and animals started to appear.

This research is important because it helps us understand how ferns and other plants have spread across continents. It also gives us clues about the climate and conditions that helped these plants thrive. By studying these ferns, we can learn more about the history of plant life on Earth.

Fern Family Feud: Unraveling the Mystery of Onocleaceae

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