Microbial communities (September 17 & 19)

Our first test is on Thursday. This is the first paleoecology exam for all of us! We’ll spend some time talking about it on Tuesday. Remember it is an open-note test, meaning you can use any of your hand-written notes. It covers from our first day through whatever we complete on Tuesday, including what we covered in lab (except for the specimens).

We will finish trace fossils on Tuesday with some applied examples of trace fossils in paleoecology. Please review the previous links.

Our main topic will be microbial communities in the fossil record and how they are a fundamental factor in evolutionary paleoecology. Please start your web-reading with the Wikipedia page on stromatolites. These are not the only microbial structures we’ll study, but they are the most prominent. Next meet our main prokaryotic players, the cyanobacteria. Oddly enough, a colleague and I actually described cyanobacteriial mats from the Upper Ordovician of the Cincinnati area. These are rare because they are replaced with pyrite and three-dimensional.

Our primary paleoecological case study with microbial mats will be the Cambrian Substrate Revolution. Microbial mats served us well as oxygen-producers and sediment stabilizers, but the tie finally came for animals to break through them to exploit the nutrients in the sediment and do all those other infernal activities we talked about with trace fossils. A Wooster alumnus, Steve Dornbos, is one of the paleontologists who developed this scenario.

Geology in the News —

Here’s a fascinating set of Neanderthal footprints found in France. Human trace fossils! They may tell us something about Neanderthal family life, information we can’t get from bones alone.

Here’s a cool super-sized pterosaur found in the Cretaceous of western Canada. Note the complicated taxonomic history to finally get this critter a proper name and description.

Trace Fossils (September 10 & 12)

Let’s start with the Wikipedia page for trace fossils. Note that trace fossils are sometimes called ichnofossils, and the study of them is ichnology. Wooster has an excellent collection of hardgrounds, especially from the calcite seas of the Ordovician and Jurassic, on which we will see many borings and other examples of bioerosion. We also have a good soft-sediment trace fossil set, much of it inherited from the late Professor Richard G. Osgood, Jr.

You will see that the large majority of our trace fossils are marine because, naturally, most traces come from marine sedimentary rocks. I wish we had more dinosaur tracks, but they are best enjoyed and studied when they are still in place.

Our summative project for trace fossils will be the descriptions, distribution, and analysis of ichnofacies. Done correctly, an ichnofacies study can reveal much about paleoecosystems.

Dr. Patricia Kelley visits class on Thursday, September 12; she will speak on drilling predation. She also gives a Geology Club talk at 11:00 a.m. in Scovel 205 (required).

Lab report #1 due in Dropbox by noon on Tuesday.

Geology in the News —

A cool trace and body fossil combination found in the Ediacaran of China. This rare kind of trace is called a mortichnium. (You can figure out those roots.) The specimen has started an interesting conversation about evidence for the earliest animal motion. Here is the original article in Nature.

Why did coyotes survive from the Pleistocene but not saber-toothed cats? Apparently coyotes, which are notorious omnivores, adapted better to changing climates and food resources.

Taphonomy (September 3 & 5)

Taphonomy, the science of fossil preservation, is one of my favorite topics in our science. Essentially, it is what happens in the fossilization process “from death to discovery”. Preservation issues are the primary reasons why information is lost in the fossil record, producing a variety of biases in our data. It is important to understand what we are not seeing and why.

One of the most common taphonomic biases in the marine record of invertebrates is the differential dissolution of calcium carbonate skeletons. Review the properties of the common minerals calcite and aragonite. We’ll also discuss terrestrial vertebrate taphonomy.

I will not be able to resist telling you about the taphonomic processes of bioimmuration and bryoimmuration! This will lead to our final discussion of taphonomic engineering.

Geology in the News —

More coprolites in the news! This time it is prehistoric puma poop that is revealing the DNA of parasites — the oldest ever.

Eumelanin (a screening pigment) has been identified in Eocene crane-fly eyes, a first for fossil arthropods. This is a nice evolution/adaptation story made possible by some taphonomic pathway.

How heat waves work. No one is escaping from climate change.

Geological time and ecological principles (August 27 & 29)

Our very first topic is geological time. Paleoecology is a historical science, so it needs a chronological system. Generations of geologists have crafted the iconic Geologic Time Scale, which will be critical to all that we do in this course. Here is our version of the Geological Time Scale. Like geologists and other Earth scientists before you, please memorize all the eon, era, period and epoch names given on our chart. (Here is the latest professional version of the time chart. You don’t need to know all those other names!)

I don’t want to overwhelm you with ecological terms from the Web. We will develop those we need within our own conceptual context. This pdf from Dr. Karen Lancour on ecological principles, though, is a nice summary. You certainly don;t need all that she has included; concentrate on her illustrations now and then return for some of the definitions. A more philosophical view is in these Ten Principles of Ecology.

Geology in the News —

There is now some resistance too the concept of a human-initiated geological time interval: The Anthropocene is a Joke. A bit harsh, but thoughtful.

There is an interesting new idea about why oxygen levels plateaued for almost two billion years during the Proterozoic. Oxygen may have limited nitrogen fixation until the appearance of land plants kick-started photosynthetic oxygen production in a big way.

Speaking of oxygen, could rising levels of atmospheric oxygen have helped increase North American dinosaur diversity? The evidence looks thin to me, but it may be a cool hypothesis to test.

Introduction to Paleoecology (August 22)

Welcome to the first Paleoecology course at Wooster! These weekly blog posts will be your guide to the concepts and materials of our course. Come here often!

The Wikipedia definition of our subject is concise: “Paleoecology is the study of interactions between organisms and/or interactions between organisms and their environments across geologic timescales. As a discipline, paleoecology interacts with, depends on and informs a variety of fields including paleontology, ecology, climatology and biology.” We have a wondrously diverse science in paleoecology, with connections to many topics directly relevant to contemporary concerns about environmental degradation, extinction, and climate change.

We need a few general links to paleontological resources to get us started in paleoecological research. Here is the University of California Museum of Paleontology (Berkeley) page on “learning from the fossil record“, with numerous educational and professional articles and links. The Paleontological Research Institution has an excellent site with introductory material (including “mystery fossils” to identify). It is oriented towards professionals and graduate students, but you can certainly have a go at it. And I can’t let you go without links to my favorite organizations: The Paleontological Society and The Palaeontological Association. You certainly want to look at the projects of Wooster paleontologists over the past few years. You may also want to visit The Paleontology Portal which is “a central entryway to paleontology on the Web”. It is an excellent link to thousands of paleontological resources. (Check out their fossil gallery, which is organized by period.)

The Time Scavengers blog is an excellent site for geology students, especially those interested in paleontology. University of Tennessee graduate students Jen Bauer and Adriane Lam have put together a fantastic collection of articles, teaching aids, and links just for students like you. They even have an interview with an evolutionary paleoecologist.

Our theme song! (Although it could use some invertebrate fossils …)

Jurassic fossils in southern Israel (Matmor Formation, Makhtesh Gadol, near Dimona). These are mussels still attached to a snail shell. Click for larger view.

Geology in the News —

Here is a story about Louis Agassiz and his 19th century throw-them-in-the-deep-end style of teaching. It is my inspiration for your first lab!