New fossils and species of the Oligocene toothed baleen whale Coronodon have been discovered.

A new study by Robert W. Boessenecker (CofC), Brian L. Beatty (NYIT), and Jonathan H. Geisler (NYIT) reports a wealth of brand-new fossils of the early toothed baleen whale Coronodon from rock layers near Charleston, South Carolina, from the Oligocene (23–30 million years ago).

These incorporate five new skulls, addressing two new species: Coronodon planifrons, Coronodon newtonorum, and young juveniles of Coronodon havensteini, which this team named for the first time from a single skull in 2017. Coronodon is one of the most crude individuals from the gathering that incorporates living baleen whales; its name means “crown tooth,” alluding to the huge, multi-cusped teeth that cross-over in the mouth. A continuous logical debate concerns whether these teeth were utilized for cutting, channeling, or a blend of both.

Coronodon planifrons and Coronodon newtonorum, two new species, were discovered in the same rock layer during the same time period (late Oligocene; 25–23 myo). These two species could have come from Coronodon havensteini, which is older (30–28 years old). Coronodon planifrons is named after a skull with a level ‘temple’ and potentially an additional tooth comparative with different species.

Coronodon newtonorum is also known from a single skull and mandible with slightly smaller teeth and an unusually shaped mouth that gave the impression of a “smile” that lasted for an indefinite amount of time.

A rare glimpse into the early growth and development of an Oligocene whale is provided by new Coronodon havensteini specimens, which include a mature adult and two calves. The snout stays the same length throughout growth rather than becoming shorter in juveniles, as is the case with modern baleen whales and dolphins. The significance of the teeth to understanding this early whale is demonstrated by the fact that the snout’s early development is probably related to its large teeth.

According to these new specimens and species, Coronodon likely swam in a manner similar to that of modern baleen whales, had a head that was proportionally larger than its skeleton, likely had a flexible chin, and likely had skull joints that are typically associated with filter feeding. However, it appears that Coronodon lacked baleen. Coronodon is the earliest branch of the evolutionary tree of baleen whales, which is essential for comprehending the transition from feeding with teeth to feeding with baleen.

More information: Robert W. Boessenecker et al, New specimens and species of the Oligocene toothed baleen whale Coronodon from South Carolina and the origin of Neoceti, PeerJ (2023). DOI: 10.7717/peerj.14795

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