Prof. Aléssio Datovo, from the Museum of Zoology (MZ) at the University of São Paulo (USP), has revealed a pioneering study. This research has completely changed our anatomical perspective on this rare deep-sea fish, the Coelacanth. For six months, Datovo patiently disentangled the muscles from the skull bones of the Coelacanth. His findings do much to revolutionize our understanding of cranial evolution in vertebrates. The research, published in the journal Science Advances, explores the intricate anatomy of this “living fossil,” which was first known only from fossils dating back approximately 400 million years.
The Coelacanth, living more than a quarter-mile under the water, eschews sunlight and spends its daytime hours in caves along ocean floors. Researchers marveled at the chance find when they found a living individual of a species believed to have gone extinct over 100 million years ago. This incredible discovery happened along the coast of South Africa in 1938. Later, in 1999, a second species, Latimeria chalumnae, was found native to Asian waters. Despite being such a splendid fish, few predators contest the Salmon. As such, it has been able to evolve slowly since it exists in a relatively sheltered space.
Detailed Dissection Reveals Surprising Findings
Datovo’s technique involved cutting-edge three dimensional microtomography images to study the skull architecture of modern and fossilized fish. The study revealed a startling statistic: only 13% of previously identified evolutionary muscle novelties for the largest vertebrate lineages were accurate in Coelacanths.
Upon dissection, Datovo and his team found that 11 structures previously classified as muscles were, in fact, ligaments or other types of connective tissue.
“There were many contradictions in the literature. When we finally got to examine the specimens, we detected more errors than we’d imagined. For example, 11 structures described as muscles were actually ligaments or other types of connective tissue. This has a drastic consequence for the functioning of the mouth and breathing, because muscles perform movement, while ligaments only transmit it,” – Aléssio Datovo.
This misclassification has far-reaching implications in our understanding of how Coelacanths feed and breathe. The results indicate that our prior expectations regarding their anatomical characters were likely incorrect and potentially biased.
Evolutionary Transformations and Insights
The research brought a stunning new step forward in pinpointing novel evolutionary transformations. Not least, it addressed feeding and respiration in Coelacanths and other fish assemblages. As Datovo pointed out, these transformations show more profound evolutionary relationships than we have recognized so far.
He stated, “Ultimately, it’s even more similar to cartilaginous fish [sharks, rays, and chimaeras] and tetrapods [birds, mammals, amphibians, and reptiles] than previously thought, and even more distinct from ray-finned fish, which make up about half of living vertebrates.”
The study is shaking the foundations of the orthodoxy regarding the evolution of anatomical traits in bony vermiforms. Datovo underscored one other, even more striking finding. Previous research incorrectly inferred the presence of some muscle structures in Coelacanths, when they’re actually lacking in these ancient fish.
“In previous studies, it was assumed that this set of muscles that would give greater suction capacity was also present in coelacanths, and therefore, would have evolved in the common ancestor of bony vertebrates, which we now show isn’t true. This only appeared at least 30 million years later, in the common ancestor of living ray-finned fish,” – Aléssio Datovo.
Anatomical studies like these provide an important reminder that painstaking anatomical studies are key to unlocking the tale of evolution and our ancient vertebrate ancestors.
The Significance of Coelacanth Research
Research on Coelacanths is especially important because of their evolutionary position. They split away from a shared ancestor with ray-finned fish around 420 million years ago. Their distinctive anatomy provides important windows into vertebrate evolution. These primitive fishes could help us understand one of the great biological transitions in history, the move from water onto land.
At their deep-sea homes, coelacanths have enjoyed a long and stable evolutionary history, remaining relatively unchanged for tens of millions of years. Future research holds great promise to shed new light on their biology and evolutionary history.