Iowagnathus

Iowagnathus is an extinct genus of large macropredatory conodont (an extinct group of agnathans) known mainly from Ordovician strata in North America, with potential occurrences in similarly aged strata from Siberia. A single species is known, Iowagnathus grandis, which was described by Liu et al., 2017 based on multiple oral apparatuses discovered in the Darriwilian aged Winneshiek Shale in northeastern Iowa. This genus is currently placed within the Iowagnathidae family, potentially as a basal member of the larger prioniodinina suborder.

This genus is rather unique, as the elements and apparatuses discovered are quite large compared to most other conodonts, with one S₀ element alone having a lateral width of around 16 mm (1.6 cm). The large sizes of the elements and apparatuses suggests a potential size of up to 1.0 m (3.3 ft) long for the full animal, potentially making this genus among the largest known conodonts yet discovered. As with most other conodonts though, no fossils preserving the body of the animal are currently known, with the potential sizes being found by comparing the size of its apparatuses and elements to those of other genera like Clydagnathus, which is known from preserved body fossils. This conodont may be one of the potential makers of the various bromalite specimens that have been found within the Winneshiek Shale, which usually include the elements of other conodonts. All of these factors suggest that this genus was a macropredator, occupying a high trophic level within its environment, a lifestyle rare in jawless vertebrates.