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Conodonts are enigmatic animals that existed for 300 million years before going extinct shortly after the appearance of the first dinosaurs. They are one of the oldest lineages of vertebrates and have been suggested to be some of the earliest vertebrates. Conodonts left behind tooth-like fossils which come in a variety of shapes, from simple 'cones’ from which they get their name (conodont=cone tooth), to broad molar-like platforms, and delicate bars and blades. Despite decades of intensive studies in academia and industry, researchers remained puzzled by the function of these teeth and how they fit into the food chain. In a newly published study in the journal Paleobiology, an international team of paleontologists sought to shed light on this long-standing question of conodont culinary choices by analyzing the chemical composition of the tooth-like fossils of multiple species.

The researchers compared species within individual ecological communities extracted from rocks over 400 Million years old from the island of Gotland, Sweden. The authors adopted a method for establishing diet from the toolbox of archaeologists: they examined the relative abundance of chemical elements including strontium, barium, and calcium, all of which are impacted by diet, to determine whether different conodont species living together in the same environment would have different dietary preferences.

Extrema adaptability to new diets

The team of authors from Canada, the Netherlands, Germany and Sweden found distinct chemical compositions for various conodont species, indicating a variety of dietary preferences and niches. Adapting to different diets has most likely been a powerful driver of the evolution of this group, leading to a myriad of shapes of conodont teeth. The scientists suspect that this extreme adaptability to new diets has been a key factor in the longevity of the group. Conodonts were enormously successful ecologically, surviving multiple mass extinctions, including the world's largest at the end of the Permian Period, an event that wiped out over 95 percent of all marine species. In that sense they were similar to mammals, whose extreme evolutionary success is also attributed in a large part to their tooth diversity.

Food strategy

As anyone who has been to a large dinner party knows, there are always a wide variety of food options available, but with limited quantities. Developing a strategy to maximize one’s intake of the most appealing dishes is paramount to going home well fed, and this principle can be extended to our ancient conodont friends as well. Adapting to consuming different foods has been among the most powerful drivers of evolution, and this study shows that conodonts may have been particularly good at finding their own dining strategies and ecological niches.

Useful fossiles

Compared to larger and more dramatic fossils these tiny eel-like organisms do not grab much public attention, but have captured the imagination of paleontologists for more than a century. The global abundance of their millimeter sized teeth, rapid evolution and their use in estimating the age of marine rocks through the duration of their existence have made them the most useful fossils in the world. This research was led by then PhD student at the ľ¹Ï¸£ÀûÓ°ÊÓ of Calgary, David Terrill, who travelled to Germany to collaborate on developing this new approach under the supervision of Dr. Emilia Jarochowska (now affiliated with Utrecht ľ¹Ï¸£ÀûÓ°ÊÓ).

Terrill, D., Jarochowska, E., Henderson, C., Shirley, B., & Bremer, O. (2022), ‘Sr/Ca and Ba/Ca ratios support trophic partitioning within a Silurian conodont community from Gotland, Sweden’, Paleobiology, 1-21.