Datovo and Johnson 2025
The authors reported in the publicity,
“Upon re-examining the cranial musculature of the African coelacanth (Latimeria chalumnae), the authors discovered that only 13% of the previously identified evolutionary muscle novelties for the largest vertebrate lineages were accurate. The study also identified nine new evolutionary transformations related to innovations in feeding and respiration in these groups.”
“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,” says Aléssio Datovo, a professor at the Museum of Zoology (MZ) at USP supported by FAPESP, who led the study.”
“Among the evolutionary novelties erroneously identified as present in coelacanths are muscles responsible for actively expanding the buccopharyngeal cavity, which extends from the mouth to the pharynx. This set of muscles is directly related to food capture and respiration. However, the study showed that these supposed muscles in coelacanths were actually ligaments, which are structures incapable of contraction.”
“The sarcopterygii include fish such as coelacanths and lungfish, as well as all other tetrapods, because they evolved from an aquatic ancestor. These include mammals, birds, reptiles, and amphibians.”
“In ray-finned fish, such as aquarium carp, it is easy to see how the mouth moves to suck in food. This is a fundamental difference from other fish, such as coelacanths and sharks, which primarily feed by biting their prey.”
The cladogram published by Datovo and Johnson
“Coelacanths are rare fishes that occupy a key evolutionary position in the vertebrate tree of life. Despite being exhaustively studied, we found that a substantial part of the knowledge on their cranial musculature was mistaken. Eleven previously reported coelacanth “muscles” are nonexistent, while three previously unknown muscle subdivisions and connections are found. These findings markedly affect our understanding of the deep-time cranial evolution of jawed vertebrates (gnathostomes).
“Only 13% of the previously identified myological evolutionary novelties for the major gnathostome lineages proved to be accurate, but several new ones are proposed. We show that low, moderate, and high levels of cranial muscle innovation characterized the emergence of lobe-finned (sarcopterygian), cartilaginous (chondrichthyan), and ray-finned (actinopterygian) fishes, respectively.”
“The novelties in the latter group resulted in the evolution of a second active mechanism for the expansion of the oropharyngeal cavity, which was probably crucial for the predominance of suction feeding versus bite feeding in extant actinopterygians.”