Beyond the Bones: Coastal Clues

Pictured: An illustration of the different species of Coronodon whale. Clockwise from left: Coronodon havensteini, Coronodon planifrons, Corondon Newtonorum (bottom right). Illustration by Robert Bossenecker

In 1859, Charles Darwin’s Origin of Species explained how natural selection caused the limbs of an extinct, ancestral species to evolve into human hands, the legs of a horse, the fins of a porpoise, and the wings of a bat. Evidence of the common ancestry remains today in a similar bone pattern.

While Darwin’s Victorian-era investigations were limited by the technology available at that time (early microscopes), today, researchers in the College of Osteopathic Medicine’s (NYITCOM) Department of Anatomy are leveraging high-tech tools and innovative ideas to look beyond the bones. Faculty are conducting cutting-edge research to help explain the ancient animals that roamed the earth millions of years ago and even some of those living today.

Across land, air, and sea, this summer New York Tech News is highlighting some of the recent studies published by these researchers. The “Beyond the Bones” series is a snapshot of just a few of the projects helping to shape scientific understanding about evolution.

In this first installment, two of the department’s evolutionary biologists contributed to a study that announced two new whale species that once inhabited the waters near South Carolina.

With nearly 3,000 miles of tidal coastline (beaches, rivers, and creeks), South Carolina is known to be a hotspot for observing pods of the bottlenose dolphin and other marine life. What is less known is that the lands 20 miles inland include some of the richest marine fossil deposits in the world. In fact, some of the earliest known baleen whales and toothed whales are believed to have lived 30 million years ago near the Atlantic coast of Charleston, S.C.

Recently, in a paper published April 14 in the journal PeerJ, Associate Professor Brian Beatty, Ph.D., and Department Chairperson and Associate Professor Jonathan Geisler, Ph.D., revealed the discovery of two whale species new to science that once swam along the region’s coast.

The study, led by College of Charleston researcher Robert Boessenecker, Ph.D., details the skeletal anatomy of new fossils belonging to the early toothed baleen whale Coronodon, whose name translates to “crown tooth.” Coronodon is one of the most primitive members of the group that includes living baleen whales, and there is much debate as to whether its teeth were used for cutting, filter-feeding, or a combination of both.

The fossilized Coronodon remains, which are in the collections of the College of Charleston’s Mace Brown Museum of Natural History and The Charleston Museum, were discovered in sediment layers as old as 30 million years near Charleston. The collection includes a total of five new skulls, representing two new species (Coronodon planifrons and Coronodon newtonorum) and young juveniles of Coronodon havensteini, a species first named by the team in 2017.

While Coronodon planifrons and Coronodon newtonorum were found in the same rock layer and are similar in age (late Oligocene; 23 to 25 million years old), Coronodon havensteini is several million years older and possibly an ancestor of the two younger species.

Coronodon planifrons had a flat forehead, smaller molars, and possibly an extra tooth position. Coronodon newtonorum had slightly smaller teeth and an unusually shaped mouth that made it look like it was permanently smiling. The new specimens of Coronodon havensteini, which include an older adult and two calves, provide new insight into the early growth and development of Oligocene whales.

Unlike modern dolphins and baleen whales, who have shorter snouts as juveniles, Coronodon havensteini’s snout appears to have stayed the same length during growth, which may be related to the whale’s large teeth, which are the size of the average human palm.

The new fossils indicate that Coronodon had a proportionally large head relative to its skeleton, swam in a style much like modern baleen whales, and had a flexible chin and joints in the skull that are typically associated with filter feeding. However, it appears to have lacked baleen (a hair-like filter-feeding system that lines the whales’ mouths).

Reconstruction of the evolutionary tree places Coronodon at the earliest branch of baleen whales, a clue that will be key to helping scientists understand how whales transitioned from feeding with teeth to feeding with baleen.

In 2017, the group also published findings demonstrating Coronodon havensteini is a transitional species on the evolutionary timeline, sitting between earlier whales that snagged fish with their teeth and modern baleen whales that filter feed with baleen.

Learn more about innovative research from the Department of Anatomy’s esteemed faculty.