Kentriodontids are a family of dolphin-like toothed whales that were widespread in the Miocene. They are sometimes considered as the possible sister-taxon to the Delphinidae, the family that includes most of the living dolphins.
Kentriodontids are common throughout the Calvert Formation. There is a general trend within the family of an increase in body size over time, with tiny Kentriodon (less than 2 meters long) found in the lower Calvert and Hadrodelphis and Macrokentriodon (~ 4-5 meters long) found in the upper Calvert and Choptank, respectively. It should be noted, however, that there are apparently still a number of undescribed Calvert taxa that may disrupt this trend.
Kentriodontids are known from the Carmel Church bonebed, based on teeth, periotics, and a few bones. The most common remains are from a large species, consistent in size with Hadrodelphis and Macrokentriodon (as would be expected given Carmel Church’s age). In the image at the top, the two teeth on the left were associated with this mandible:
However, there are hints of a smaller kentriodontid species at the quarry. We have several periotic bones that appear to be from a very small kentriodontid (although I can’t yet rule out some other taxon):
The third tooth from the left in the top image was collected at Carmel Church on our last excavation. It is notably smaller than the large species, but it seems a bit large to go with the tiny petrosals.
There is an undescribed kentriodontid from the top of the Calvert, sometimes referred to as the “medium-sized kentriodontid”. We have a specimen apparently from that species that was collected a few years ago from Westmoreland County; its tooth is on the right in the top image. While its length is comparable to the Carmel Church specimen, the proportions and crown shapes are quite different.
I’m not sure what to make of this new tooth. Is it a separate medium-sized kentriodontid species? Or is it just a small individual of our large kentriodontid? I have to admit I lean toward the latter explanation, but we’ll have to see what else turns up in our material.