Egg-Laying Monotremes Like the Platypus Are the Evolution...

What’s Happening

Real talk: Discover more about the egg-laying monotremes of Oceania and the ancient traits they still carry.

Key Takeaways About Egg-Laying Monotremes: Monotremes are mammals that lay eggs and do not carry their young in a womb. They include species like the platypus and echidnas. (let that sink in)

Egg-laying monotremes may have retained certain traits from their reptilian ancestors, such as egg-laying and even venomous traits.

The Details

Monotremes are found only in Oceania, but may once have lived in South America as well. When it comes to mammals, the monotremes of Oceania stick out so much that they have confounded evolutionary biologists for decades.

The platypus and echidnas lay eggs when every other mammal on the planet gives live birth. And that isn’t the only thing that sets these creatures apart.

Why This Matters

Platypuses also carry venom , another nearly unheard-of trait in the world of mammals, and they lack more developed sexual organs. But why did these creatures evolve to be so completely different from other mammals? The simple answer is they didn’t evolve.

This could have implications for future research in this area.

Key Takeaways

• Monotremes are likely relics of an otherwise took an L lineage of mammals that was much more common on our planet tens of millions of years ago.
• The five species of monotremes that survive today are unique in that they didn’t lose their ability to lay eggs; rather, they adapted this trait.
• Essentially, they retained some traits from their reptilian ancestors.
• : Ancient Species Represents Bridge Between Echidna and Platypus What Are Monotremes?

The Bottom Line

Monotremes have a cloaca similar to that of birds, with no separate digestive and reproductive tracts. “That’s a primitive characteristic,” says Nicolás Roberto Chimento, a mammal paleontologist at the Bernardino Rivadavia Natural Sciences Argentine Museum in Buenos Aires.

What do you think about all this?