Modern Fish, Coelacanths, Tiktaalik, and Us

Tiktaalik roseae, illustration
An illustration of Tiktaalik roseae from Wikipedia. Credit: ArthurWeasley.

In the last several years, scientists have mapped in detail the lines of descent that resulted in aquatic vertebrates (fish) being able to survive and function outside water—including lines of descent that today have resulted in the mammals. Periodic discoveries stimulate interest in the media, such as the discovery last year of the 375-million-year-old Tiktaalik, or occasional sightings of coelacanths, an order of fish once thought to be long-extinct. But how are these animals related to each other and to us?

New Scientist published an article last week discussing new research into the coelacanth’s fins (specifically, when the difference between the coelacanth’s symmetric appendages and our asymetric appendages arose). But what I found especially interesting was a graphic demonstrating the relationships between extant lifeforms and notable extinct relatives, including when they are thought to have lived.

Diagram showing relationship between extant fish and tetrapods and extinct relatives.
See full-sized image. Source: New Scientist.

Perhaps this will help provide a framework when reading about these fascinating animals.

2 thoughts on “Modern Fish, Coelacanths, Tiktaalik, and Us

  1. this evolution history are really fascinating. the advanced living form today ,such as human being and other mammal,just evolve from this original living form. sometimes my mind always wondering our science and culture history and our evolution history .i find this is such a amazing history with so many miracle. even rely on our current technology , we can change ourself. so i always say”that is nothing impossible in world”
    but i believe the human technology and our power shouldn’t overuse, we should have a good harmony relationship with our nature and other animal , we should believe our human is not almighty , we also have our limitation , i get this idea from my traditional philosophy. it is :”to have good harmony with our nature.”

  2. It is very interesting to look at both the shared structures/systems and the ways in which our lines of descent have diverged. We and fish are not that different, fundamentally. And our blood and other body fluids betray our origin in saltwater environments.

    I agree that living in harmony with nature and the rest of the world is important. As Zeno said: “The goal of life is living in agreement with nature.”

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