Fossil Plants Trip Summary!

Well, it’s that time of year again when northerly organisms shut down for the cool months ahead. But, the naturalist’s mind and curiosity are never in hibernation! Our Young Naturalists’ Society therefore headed east of Bellingham, under the expert guidance of PhD candidate Elisha Harris (of the Strömberg lab at UW), to find organisms that are inert to cold weather…fossils!

Early in January 2009 a large rainstorm inundated Whatcom County, Washington, with rain and warm weather that ultimately led to hundreds of debris flows across the snow-covered foothills in the region. The largest landslide resulted in deep bedrock failure that released 500,000 cubic meters of rock! Although the landslide may have devastated local ecosystems, it left behind large amounts of fossil-bearing rock that local paleontologists have been fascinated with ever since! The rocks exposed at this site preserve remains of ancient animal and plant life that existed in Washington during the Eocene, 50 million years ago, when western Washington was characterized as a subtropical floodplain environment! A bit different from today, eh? Well read on!

Due to the landslide, a wealth of plant fossils and some vertebrate tracks were exposed giving paleontologists an idea of what this region of Washington looked like millions of years ago. The most frequently encountered plant taxon was a species of palm that shares many characteristics with modern fan palms. Many fossil fronds were well intact and large, some spanning >3 feet!

We also quickly began to recognize bald cypress, a species that left many small organic compressions of both stem and needle in the sandstone. Even though these fossil impressions were formed by organisms that lived millions of years ago, certainly long enough for appreciable morphological change to occur, it was striking how morphologically similar many of the species we discovered were compared to their extant relatives. We witnessed this morphological conservation in alder leaves as well as in ferns that were in fact not “terrestrial” or sessile ferns, but were actually tree ferns! A few of us noticed trunk impressions left behind by these tree ferns which were very reminiscent of extant tree ferns one can find in the tropics today. How cool is that?!

Because vertebrate trace fossils were much less abundant, their discovery excited many of us! An undergrad in Dr. Caroline Strömberg’s class (Biol 447: Greening of the Earth) spotted some footprints that most likely belonged to a proto-horse, Hyracotherium, that looked nothing like the hooves of extant horses to which we are accustomed. Hyracotherium had three toes on its front feet and four toes on each of its hind feet! Crazy, huh? Another YNS member stumbled upon a nice rock full of bird trackway impressions.

And those YNSers that were interested in living vertebrates were excited when they heard and saw a pika as well! There were also some birds to be seen from time to time but most everyone was focused on the fossils (well, at least for this trip)!

Many of us returned to Seattle heavier than we started, as this site is on WA DNR (Department of Natural Resources) land, and taking a small number of plant fossil impressions is allowed (not the case for animal fossils, trackways, or rare invertebrate fossils). This field trip opened up many of our eyes to the study of paleontology, and the phrase “I could see myself doing this for a career!” was confidently proclaimed by many YNSers with rock hammers in-hand. The exposure to new areas of biology and the excitement that goes with it is exactly why the YNS was started, and we look forward to this sentiment being a motif throughout our trips to come!

-Jared

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