Sucking is an especially effective way of feeding underwater, and adaptations to improve it have evolved numerous times in jawed vertebrates. The only major group of living mandibular vertebrates that does not include specialized sucking feeders is chimeras, a handful of anatomically conservative fish species that feed on hard-shelled prey. By contrast, in the Carboniferous period, between 359 and 299 million years ago, various chimeras formed a prominent part of aquatic ecosystems. In new research, paleontologists from the University of Birmingham and the Sorbonne University used well-preserved fossils of one of these Carboniferous chimaeras, iniopera, to rebuild the muscles of your skull. Their results show that iniopera it had a forward-facing mouth and the expandable pharynx characteristic of high-performance suction feeders. This suggests that in the Carboniferous, some chimaeras were suction feeders in the water column, an ecological niche since then monopolized by neopterygian fish.
iniopera what kind of iniopterygiuma group of chimaera-like cartilaginous fish known from the marine faunas of the Carboniferous period.
Among these creatures, iniopera it is the only taxon known from remains preserved in 3D, which include the skull, jaws, shoulder girdle, pharyngeal skeleton, and brain.
“Being able to identify iniopera as a suction feeder sheds light on the diverse role of chimaeras in these early ecosystems,” said lead author Dr Richard Dearden, a researcher at the University of Birmingham.
“In particular, it suggests that in their early evolutionary history, some chimaeras inhabited ecological niches that are now monopolized by ray-finned fish, a far cry from their modern life as specialized shell-crushers.”
“Because the skeletons of chimaeras are composed mainly of cartilage, their fossil remains are often flat and therefore difficult to extract information from them.”
“However, by studying the various body and tooth shapes, researchers already knew that there were many more and more varied species of chimaera living in the Carboniferous than there are today.”
Using 3D imaging techniques, Dr. Dearden and his colleagues reconstructed the skeleton of the head, shoulder, and throat of iniopera.
They then estimated the location of the major muscles and found that the anatomy was unsuited for crushing hard-shelled prey.
Instead they believe iniopera it was more likely that it had used the muscular arrangement to expand the throat to take in water and a forward-pointing mouth to orient itself towards prey.
“Suction feeding is a technique used by many animals that live underwater,” the researchers said.
“It involves generating low pressures in the throat to attract water and prey.”
“To do this effectively, the animal must be able to rapidly expand its throat and point its mouth towards prey.”
“Many different jawed aquatic vertebrates, such as ray-finned fish and some turtles, have evolved specialized anatomies to help them suck feed more effectively.”
“Our suction feeding theory also fits with other evidence, including arthropods preserved within the stomachs of other specimens.”
the recommendations were published in the Proceedings of the National Academy of Sciences.
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Richard P. Dearden and others. 2023. Evidence for high-yield suction feeding in the holocephalan of the Pennsylvania stem group iniopera. PNAS 120 (4): e2207854119; doi: 10.1073/pnas.2207854119
