The skull and jaws of Isthminia panamensis (USNM 546125) carefully posed in near-life articulation by NMNH Imaging. (Photo: NMNH Imaging / Smithsonian Institution)
Careful readers of this blog probably recognize this skull and jaws, but perhaps not the name that goes with them. Finally, after four years of hard work, my colleagues and I are happy to announce the newest fossil cetacean, Isthminia panamensis, published today in PeerJ (open-access and online).
This fossil was originally found in 2011, and in a race against the tides, it was collected by NMNH and Smithsonian Tropical Research Institute staff in a matter of hours (see expedition posts Part 1, Part 2 & Part 3, including links to other posts elsewhere, as well). The specimen then traveled to NMNH, where it was carefully prepared, and dedicated study could begin in earnest. In the meantime, we had the specimen 3D digitized, and it was actually released in late 2013 with the inaugural suite of 3D models on the Smithsonian X 3D platform. The fact that a 3D model of Isthminia was available to manipulate, measure, and 3D print before we even finished the science is just one of the disruptive aspects of this technology, in a positive way. A 3D print of Isthminia is actually on display at the BioMuseo in Panama right now!
A reconstruction of Isthminia, swimming in the Central American Seaway, about 6 million years ago, including one feeding on a flatfish. The corpulent and flexible necks, like today's Amazon River dolphin, are conjecture, while other guesses, such as the counter-shading are well-informed inferences based on today's oceanic dolphins. (Credit: Julia Molnar).
What we discovered was that Isthminia was very much a marine dolphin, with a body size like today's ocean dolphins, skull and snout shape to match. At around 6 million years old, Isthminia is also the closest relative, among all fossil and living dolphins, to today's Amazon River dolphin, and thus gives us a window into the marine to freshwater transition that we know happened in the history of many so-called 'river dolphins,' but hasn't really been revealed by the fossil record. In fact, there's a lot more of the skeleton of Isthminia preserved than many other closely related fossil taxa (belonging to the group Inioidea), making this find ever more important. And, as the world's most digital fossil dolphin, we hope other researchers will find the open-access publication (and open-access 3D models) not just fun, but useful for scholarship as well.