New research led by Flinders University paleontologist Dr. Alice Clement showed that the cranium of an Australian fish fossil had given insights on evolution, particularly on how the fish first left the waters and invaded the land.
The press release via EurekAlert! reported that this big-headed fish is the Cladarosymblema narrienense, a 330 million-year-old fish that lived during the Carboniferous Period and was found in Queensland. Scientists have previously identified this fish as the ancestor of the first land animals of four-limb vertebrate tetrapods.
Ancient Big-Headed Fish May Be the Key to Evolution, Brain Scans Show They Left Water to Invade Land
The Rise of the First Tetrapods
According to the and volume of Evolution: Education and Outreach, scientists, previously proposed that creatures with fins that lived in waters once crawled up onto the land and since then evolved into many species. This theory was recognized by the general public and featured in various media and books on prehistoric animals.
But the details on this theory are a little off, with a few hard facts to back it up. Thus, it is possible to misrepresent the theory because of the inverse proportion of data.
On the other hand, information and ideas about the fish-tetrapod transition have expanded in the last decade and changed enormously that scientists can now refer to a wealth of fossils and evidence to generate potential models and testable hypotheses on how fish moved from water to land.
Scientists have shown that forelimbs and skulls became modified before hind legs and started adapting for supporting the head and the front of the body out of the water that is likely associated with modified air-breathing. The origin of tetrapods coincides with the Early Carboniferous, and recent studies give clues to the origin of their limbs that help them live on land.
Scans Showed Brain of Ancient Fish Adapted for Life on Land
The Cladarosymblema narrienense lived some 330 million years ago in what is now Australia, Sci-News reported. It was first described in 1995. Scientists identified it as a fossil from the Early Carboniferous and a member of a group of tetrapodomorph fish from the Denovia period to the Permian period called Megalichthyidae.
Paleontologist John Long, a professor at Flinders University, said they chose to study the big-headed fish from Queensland because it is one of the best-preserved of its kind, being in a perfect 3D shape.
In the study titled, "A Fresh Look at Cladarosymblema Narrienense, a Tetrapodomorph Fish (Sarcopterygii: Megalichthyidae) From the Carboniferous of Australia, Illuminated via X-Ray Tomography" published in the journal PeerJ, researchers studied two well-preserved specimens of the Cladarosymblema narrienense and found that the ancient fish has a brain similar to its eventual terrestrial descendants compared to the brains of fishes that remained underwater.
Sophisticated CT scans revealed that the never-before-seen morphological details of the gill arch skeleton, the palate bones, the should girdle, and cranial endocast that giving clues to its brain.
They also noticed that the area in the brain for the pituitary gland is relatively large, which suggests that it has a significant role in regulating various endocrine processes. That means the brains of these ancient fish were adapted for life on land.
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