How did the fins of the Devonian fish evolve to the edges?

Abdul Hakim Mahmoud

Scientists believe that life on Earth emerged from the oceans millions of years ago, and they also believe that the genetic blueprint of quadruped animals was part of the genetic makeup of ancient fish.

In search of how the fish's fins evolved to the edges, and how the fins of the fins changed to arms, legs and fingers in quadruped creatures, the journal Prospider of the National Academy of Sciences published in its December 30 issue. Researchers from the University of Chicago Medical Center.

The paper was launched from the study of fossilized fish from the Devonian period, which spanned from 419 million to 359 million years ago, and it is the age that was known as the fish era due to the great diversity witnessed by the fish of that era, as well as due to the development of the vertebrates of the vertebral limbs from the fennel fevers, represented today by amphibians and reptiles. And mammals and birds.

Devonian fish
The study by the researchers' team examined three species of Devonian fossilized fish with primitive traits of quadrupeds, which were discovered by paleontologists at the University of Chicago in 2006 led by Dr. Nile Schoppen, a paleontologist at the university.

These are: Sauripterus taylori, Eusthenopteron fordi, and Tiktaalik roseae.

Paleontologists from the University of Chicago have used computerized tomography scans to examine the shape and structure of fin rays while still covered with surrounding rocks, and to build digital 3D models for each fin.

According to the statement issued by the University of Chicago, imaging tools allowed researchers to build three-dimensional digital models for each fin, as much research on the fins during this major transition focuses on distinct large bones and cartilage pieces that correspond to those in the upper arm, forearm, wrist, or so-called Internal structure, and how these bones changed to become parties.

Fins to tips
According to the examination with a three-dimensional computerized tomography scanner, the researchers found that it was believed that both sorbitus and eustinoperon were completely aquatic and used their pectoral fins for swimming, although they were able to support them at the bottom of lakes and streams.

As for the third type of tectalic rosy, these fish were able to support most of their weight with their fins and may use them to get out of the water to make short trips through the sabkha and muddy pools.

Tectalic fish discovered in Canada's Arctic are fish integrated with scales and nostrils, but they have a flat head and unfamiliar fins.

Its fins contain thin rowing bones like most other fish, but they also have strong inner bones that allow them to swim forward in shallow waters and use their limbs for support, as do most of the four-legged animals.

In this regard, Dr. Schoppen said, "By seeing the entire Tikatalik fin, we gain a clearer picture of how it is supporting and moving."

On the other hand, models showed that the rays of these fins were simplified, and the total size of the net of fins was smaller than their fish predecessors, and surprisingly they also noticed that the top and bottom of the fins became asymmetric.

Thomas Stewart, one of the study participants, said, "This provides more information that allows us to understand how the tectalic were using its fins in this transition, as it moved from swimming freely and used its fins to control the flow of water around it, to adapt to pressure on the surface at the bottom of the water. ".