31 May 2013

The Mammoth Prairie

Mammoths & Sabertooth Cats (Zdenek Burian)
For several years now, I have been based in Oregon, first as a grad student and then as an instructor.  This blog, originally intended as a way of staying in touch with friends in family in a pre-Facebook age and subsequently evolving into a sounding board for my thoughts on paleontology, has always been written from an Oregonian perspective (hence its name).  However, I was fortunate enough to get a postdoc at Cornell College in Iowa, where I will be moving later this year.  I have only just started getting back into blogging and it's something I want to not only continue, but to do more of.  I intend to keep this site going, and at this same URL, but as Iowa is a long way from Eugene or Roseburg and since the Oregon Trail began one state to the south of where I'll be, the current title of this blog will clearly need to be changed.  I'm currently leaning towards 'The Mammoth Prairie" as a tip of the cap to the mammoth fossils uncovered near where I'll be living (and in recognition of the fact that mammoths and mastodons are likely to become a stronger focus of my research over the next few years) as well as to the tallgrass prairie ecosystem that historically covered most of Iowa.  I also like the name because it has echoes of the 'mammoth steppe,' the name coined to describe the dry tundra environment of Arctic North America and Eurasia during the Pleistocene and a phrase that I've always found highly atmospheric.  Before I make the change, though, I thought I'd field thoughts on the name and alternative suggestions from whatever is left of my reading audience, so let me know what you think.

24 May 2013

Bellingham's Big Bird

DiatrymaUniversity of Wyoming Geological Museum
Note: I wrote this post some time ago when this was actually breaking news. It no longer is, but at Edward Davis' urging, I'm trying to get back into active blogging, and I thought I'd begin by finally posting this.  Bona fide new posts to follow.  Eventually.

The western half of the Northwest is, for the most part, a geologically young landscape, shaped by the still-growing Cascades and by sediments deposited during the Pleistocene.  The fossils found here are, for the most part, correspondingly young.  In the Puget Sound Lowlands and the Willamette Valley in particular the vertebrate fossil record is dominated by Ice Age mammals (including the Manis Mastodon).  However, there are pockets of older rocks in the region, including the Oligo-Miocene formations of the outer coast that have yielded some of the world's most important specimens of marine mammals and the marine reptile-bearing Cretaceous rocks along the Strait of Georgia.  Among the most unusual vertebrate fossils in the region are those from the Chuckanut Formation near Bellingham.  In the Eocene, the area was a low-lying floodplain in a warm climate (as indicated by the palm fronds that have been found there).  Bones of fossil vertebrates are rare in the formation, but many animals left their footprints in the then-soft sediments of the floodplain, several of which have been preserved as fossil trackways.  Trackways and other trace fossils are invaluable paleoecological tools, as they preserve direct evidence of interactions between organisms and their environment.  A recent publication out of Western Washington University describing a pair of giant bird tracks from the Chuckanut Formation is a nice case study of the use of fossil footprints in making inferences about the behavior of extinct animals.  One of the Eocene's most charismatic animals was the giant flightless bird Diatryma (possibly the same animal as the European Gastornis of BBC fame).  Diatryma bones are well-known from the Eocene beds of Wyoming, and when it was first discovered by Edward Drinker Cope in the late 19th Century, it was thought to be a carnivore and was frequently depicted as preying upon the small horses that were common in the area.  However, it has subsequently been hypothesized that Diatryma was herbivorous, possibly using its large beak to crack nuts or fruit rinds.  The Washington tracks have been tentatively assigned to Diatryma or a close relative; while assigning trace fossils to a taxon previously known from body fossils always entails some risk, but since no other large birds are known from the Eocene of North America, in this case the authors are not going out on too much of a limb.  If the tracks were indeed made by Diatryma, they provide some hints as to the animal's behavior, as they don't seem to show any evidence of the sharp talons that characterize modern predatory birds (including, significantly, the terrestrial secretary bird).  This is not, of course, the final word in the debate; it's entirely possible that if Diatryma were a predator, it relied more on its beak than its feet for hunting, and it's not outside of the realm of possibility that evidence of talons simply wasn't preserved in these tracks.  However, the footprints do provide a novel viewpoint, and it is certainly to be hoped that the Chuckanut Formation will continue to produce fossils that will help elucidate the ecology of Eocene ecosystems.