The authors of a recent PLOS ONE study describe a small dolphin skull discovered in Ecuador, which they identify as belonging to a new species based on its facial features. Previous dating of the site where it was found allowed the researchers to estimate the dolphin may have lived 24 to 26 million years ago, during the Oligocene epoch.
“The skull was found in one of the first expeditions to a coastal cliff near Olón, in some fallen rocks that previously yielded some shark teeth,” says study co-author Juan Abella. “We first saw the tip of a skull in the rock, with nothing else showing. However, as I cleaned loose sediment from the rock with a brush, two earbones appeared. More bones became apparent, although other parts of the skull were lost to erosion, probably by waves.”
The study’s lead author, Yoshihiro Tanaka, further explains their research in the interview below.
How did you come up with the name Urkudelphis chawpipacha for this new dolphin species?
YT: The generic name, Urkudelphis originates from “urku,” a word in the Kichwa language in Ecuador that means “mountain,” referring to the type locality of Montañita, and the Greek “delphis,” which has been used widely as a suffix for dolphin generic names. Chawpipacha results from the combination of “chawpi,” meaning “half” or “middle,” and “pacha,” meaning “the world,” representing the equator.
How does this new species differ from other Oligocene dolphins?
YT:Urkudelphis chawpipacha differs in that it has widely exposed features known as frontals at the vertex in the top of the skull and a strongly pointed feature on one of the ear bones. This bone, termed the periotic, is often unique for a given species.
Why is it significant that this dolphin fossil was found near the equator?
YT: Urkudelphis chawpipacha is one of few fossil dolphins from the equator area. Most material described from the Americas is from more temperate regions, but work in recent years has focused on describing fossil cetaceans in tropical areas of the Americas. Understanding the biota that lived in tropical America sheds new light on a major event in Earth’s history: the emergence of the Isthmus of Panama that links North and South America, which had a major impact on oceanic and atmospheric currents, and ultimately global climate and diversity. The dates for this event are still a matter of strong debate, but the dolphin described here lived before the rise of the isthmus.
Was there anything that surprised you about this new species?
YT: Most new species are a surprise. The new dolphin, Urkudelphis chawpipacha, differs in many fine details from previously named species. The sole specimen is a young animal rather than an adult, and its skull roof is primitively wide. We have compared it with other fossil dolphins from New Zealand, Oregon and Washington states. Until now, Ecuador had no named fossil dolphin species. Now, Urkudelphis chawpipacha is an important new and unexpected record for archaic dolphins.
What do you plan on studying next?
YT: Some of us continue to study dolphin evolution in New Zealand, Switzerland and Japan. Some of us are teaching at Universidat Estatal Peninsula de Santa Elena, Ecuador, and are working on local geology and paleontology. Our Ecuadorian project is likely to yield more interesting fossil dolphins in the near future.
Reference: Tanaka Y, Abella J, Aguirre-Fernández G, Gregori M, Fordyce RE (2017) A new tropical Oligocene dolphin from Montañita/Olón, Santa Elena, Ecuador. PLoS ONE 12(12): e0188380. https://doi.org/10.1371/journal.pone.0188380
Image Credit: Tanaka et al (2017)