Evolution: Phylogeny and Platypuses

I know. Platypuses. I’m sure 75% of the people who are reading this post (or sentence for that matter) were attracted to the content of “platypuses.” No worries, the title is not misleading. This is about platypuses. And evolution.


Water-colored painting of duck-billed platypuses by Heinrich Harder.

Ornithorhynchus anatinus or also known as the platypus is a unique monotreme species indigenous to eastern Australia. Monotremes are mammals that lay eggs instead of giving birth, and currently, the platypus is one of the five existing montrome species. With its eclectic duck bill, beaver tail, and pain-shocking venom, to name a few, the platypus has long amazed the naturalist community. Due to its unique appearance and biology, the platypus has found its lineage branching off from an internal node that separates it from the eutherian mammals (unique characteristics include placenta and advanced development before birth).

In other words, monotremes, like the platypus, find themselves classified separately from eutherians, such as mice and us, humans.  Platypuses are often depicted evolutionarily in diagrams such as the one below. They are displayed farther to the left, near reptiles, but it is a common mistake to assume platypuses or monotremes are less advanced than eutherians due to its placement to the left.

Moosmosis_Phylogeny Platypus

Moosmosis: Evolutionary Tree and Phylogeny of Reptiles, Platypuses, and Eutherians

Many of us often fall into the erroneous trap of “ladder thinking.” “Ladder thinking” is the idea of organizing things into categories of “lower” and “higher” forms. The species to the left and on the edge are the lower forms, and as we get closer to the right (always happens to be where evolutionists place us humans), we believe we are getting to the “higher” and more advanced forms.

This ladder thinking is wrong. Remember that evolution is not a ladder, but rather a tree of life, as emphasized by the renowned biologist Charles Darwin.

Moosmosis_Phylogeny Platypus 2

Switching Eutherians and Platypuses on the Evolutionary Tree

Platypuses, then, are not “un-advanced.” It is true that instead of giving birth, they lay eggs, a biological reproduction that is more related to the ancestral mammals of therians.  It is also true that animal teats are not present on platypuses compared to their eutherian cousins. However, if we switch the placement of eutherians and platypuses, we can see that platypuses have electrochemoreceptors and webbed feet that eutherians and we humans do not have. In that case, we are “primitive,” right? *

Works Cited

* Nope

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