30 November 2015

Paleontology Advent Calendar 2015: Lagerstätten, Climate, and Paleoecology

Cenozoic Climate
Modified from Zachos
et al. 2001
One of the things we take for granted in today's climate, particularly those of us from areas far distant from the equator, is that winter is cold and dark.  This is, of course, generally true, and the reason that so many cultures have developed holidays that celebrate togetherness, warmth, and light and that fall on or near the Winter Solstice - Christmas, Hanukkah, Diwali, Yule...the list goes on and on.  Thanks to axial tilt, winters will always be colder than summers, but Earth was not always the icehouse it is today.  Earth's climate is warming, but it's worth remembering that our starting point was the Pleistocene Ice Age, the coldest interval in Earth's history since at least the Permian (this is a big part of the reason that climate change has the potential to be so disruptive).  Go back in time to any other point in the Cenozoic and things would have been considerably warmer.  In fact, at the risk of oversimplifying, the story of climate since the extinction of the dinosaurs has been one of a decrease in temperature, though as you can see on the climate curve at left, there have been several spurts of both warming and cooling along the way.  As climate has changed over the last 66 million years, organisms and ecosystems have changed along with it, and a big part of my work is examining precisely what changes have been wrought and what might be brought about by future climate change.  Fossils from sites across the globe have helped illuminate this story, but some localities shine brighter than others, either by preserving huge numbers of fossils or by preserving fossils in exquisite detail.  The sites are known as lagerstätten, a German term loosely translatable as "Storage Place."  A site that preserves fossils in impeccable detail is known as a konservat-lagerstätte, a site that preserves a large concentration of fossils is a konzentrat-lagerstätte, and together these localities comprise the most spectacular record of past life and ecosystems.  Using lagerstätten as a foundation, my holiday gift to my readers (a gift that, like so many that you'll be encountering over the next few weeks, was unrequested but that you're getting anyway) is to tell the story of how life on land has been shaped by climate as it has cooled since the end of the Cretaceous.  The story has played out as the grandest of pageants, but I'm going to be telling it in another seasonably appropriate format, and one that lends itself both to blogging and to my own personal tastes: an advent calendar.  As a kid, I loved the countdown to Christmas almost as much as the holiday itself.  There's something very satisfying to an organizational mind about peeling back a window each day to reveal some colorful scene within and I suspect that I'd have enjoyed the experience even more if, instead of wreaths and candy canes, each window had revealed a spectacularly preserved fossil.  So, each day starting tomorrow and ending on the 24th, I'll be featuring a photo of specimens from a particular lagerstätte (taken by me unless otherwise noted) and doing my best to fit it into the bigger picture of Cenozoic ecology and evolution.  Note that the definition of precisely what constitutes a lagerstätte is a bit fuzzy; my criteria are that either someone must have referred to a particular locality as such in print or made direct comparisons between a locality and a widely recognized lagerstätte (I should mention that I've leaned heavily on this book, the Bristol lagerstätte site, and Wikipedia while selecting sites to include).  Besides the photo and a brief blurb about each site, I'll also be including basic geological data, information about how to visit the site or specimens it has yielded, and lists of publications for those of you who have people on your shopping list that really like gorgeous photos of beautiful fossils.  Enjoy, and Happy Holidays!

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