Colorful marine mollusk fossils from Louisiana
The fossil remains of marine mollusks have played a pivotal role in the understanding of stratigraphy around the world. Recently, Palaeontologia Electronica (PE) authors Lloyd Glawe, John Anderson, and Dennis Bell published an article about their study of microscopic mollusk shells from a set of nearly continuous cores from the Paleogene of Louisiana. The authors state, “the mollusk shells were available in an unusually long subsurface core representing 6 million years of nearly continuous, deltaic deposition.” The subsurface cores spanned over 650 meters in length and are estimated to extend from ~60 Ma to ~54 Ma, which allowed the authors to modify the known stratigraphic range for certain species of marine mollusks from the Gulf Coastal Plain of the United States.
Geographic setting and location of the study well in NW Louisiana
Specimen ZPALWr. A/4005 from SE Poland
Look out the nearest window and try and spot a bird. While the PE blog audience is joining me from multiple continents and environments, it’s likely that no matter where you are, the bird you see is in the order Passeriformes. This order includes more than half of all extant bird species in the world, including the well-known songbirds. What makes a bird a member of the Passeriformes order? There are a bunch of technical, complicated characters that distinguish passerines from other birds, but one feature that is significant has to do with the arrangement of the toes. Passerines have an anisodactyl arrangement of toes, meaning that three digits point forward while one lone digit (hallux) points backward.
Toe arrangements in birds (anisodactyl in upper left corner).
Back in December Edward Davis and Brianna McHorse published a paper in Palaeo-Electronica (PE) about using astragali to identify camel genera from the Thousand Creek locality in Nevada. They have written their own blog post about this research, which can (and should) be read here; though I’ve included an excerpt from their blog to introduce their research to the PE blog audience:
“Many Miocene fossil sites are full of camel ankle bones (and ankle bones of other animals, too, but you have to start somewhere!). Ankle bones are small, compact, and extremely durable. They are also in a part of the animal that doesn’t have much tasty, tasty meat. As a result, they often escape significant damage from banging against rocks during transport before burial or by scavenging…
…Most fossil mammals are identified by looking at details of the skulls and teeth. At some sites, like Thousand Creek in Nevada, skulls are extremely rare but ankles and other foot bones are super common. If we want to know what camels lived in Thousand Creek 8 million years ago, skulls are not enough. Instead, we need to be able to identify all of these ankle bones. At a basic level, this lets us know what kind of camels lived there, but that’s important for more than just paleontological trivia. Those little bits of data go into larger-scale studies of evolutionary and ecological dynamics. Each time we increase our knowledge of a single fossil site, we add another brick to the foundation of our largest-scale analyses, improving our ability as a species to predict how our earth’s fragile ecosystems will behave as we turn up the thermostat.”
So how do you identify ankle bones?
Illustration of astragali showing the dimensions used in Davis & McHorse 2013 Continue reading
The new zotero 3.0 comes with updated styles, but the conversion caused some errors. Furthermore, the changes we made to the PE style had not been implemented. That’s all fixed now, and you can get the new, correct style here (zip file, 9 kb). On the zotero site it will also soon be available.
This place has been quite as a grave for a long time. That downtime was caused by a number of factors, most significantly the simple fact that I was totally overworked, and that my blogging time went to my own, personal blog.
Additionally, PE was totally revamped, and a lot of papers came out of our backlog caused by last year’s special issue. Add to that a number of papers where authors’ revisions took a long time, which also made it to publication, and there simply was very much work to do for all involved, including the style editors, Daniela Schwarz-Wings and me.
Now, though, I hope to revive the blog, with a series of overdue articles.