10 November 2011
Fossil Vertebrate of the Month: Shonisaurus popularis
Society of Vertebrate Paleontology held its annual meeting in Las Vegas. The conference logo - one of the best I've ever seen for an SVP meeting - featured the ichthyosaur Shonisaurus, Nevada's state fossil (shown in the picture at left in the new Nevada State Museum, Las Vegas). Shonisaurus was a remarkable animal. Dating from the Late Triassic, it was not only one of the earliest ichthyosaurs, but at 15 meters in length was also among the biggest (the largest known ichthyosaur was the Triassic Shastasaurus, which has been reported from Oregon, British Columbia, and Northern California, among other places). Shonisaurus skeletons have been found in large numbers - and in remarkably good condition - in Berlin-Ichthyosaur State Park southeast of Reno, making it among the best-known early ichthyosaurs. The concentration of skeletons at the locality has been interpreted several different ways through the years. It was originally thought to represent a stranding site, but the lithology and paleontology of the site indicate a deep water environment. It has also been interpreted as evidence of an ichthyosaur breeding ground, though the lack of juvenile specimens contradicts this hypothesis. The generally accepted explanation for the bone bed is that it represents an area of upwelling that would have brought nutrients up from the deep sea, supporting a diverse ecosystem in which Shonisaurus would have been the top predator. Unfortunately, Shonisaurus has also been the subject of an exceptionally high-profile and exceptionally shoddy study this year that used the arrangement of skeletons as "evidence" of an exceptionally intelligent cephalopod; the readiness with which a talk on the subject was accepted by the Geological Society of America and the eagerness with which it was reported by the media are black eyes for paleontology and for scientific journalism.