August 20, 2012
Howdy! Saturday night we returned from our Andean fossil adventure – what did we find? Post your guess in the comments, and tomorrow I’ll explain the photo. Hint: the black and white stripes are each 1 cm. To read about our expedition, click on the Andean Fossil Hunt link to the right.
August 16, 2012
Time to explain our mystery fossil!
Scott is correct – it DOES look kind of like something was coming out of a hole on the left of one of the orange tubes.
These are fossils of burrows – tubes dug by animals on the seafloor. The block we’re looking at in the photo is turned on it’s side, and we’re looking at the underside. The orange color is a coincidence of the sediment type and weathering processes. It nicely highlights the shapes for us.
In healthy ecosystems, marine critters live above, on, and in the sediment at the seafloor. But how to preserve these burrows? It can be difficult, because storm and wave activity can erase the trace that these burrows ever existed. Typically we only record fossils of burrows that were deeper – at least 20-30 cm into the muck.
These burrows in the photo are called, “Thalassinoides”. We name trace fossils independently, because we’re rarely sure of the tracemaker. These kinds of burrows – deep, diverging, with many chambers – are associated with shrimps in the modern ocean. There’s very cool modern work done on these burrowing shrimps – especially by Dr. Wiebke Ziebis at USC.
Burrows are amazing. Once you learn how to see them in rocks, you can’t UN-see them! It was a blast showing off lots of photos of burrows during my talk at the Geological Society of Peru today. Some people there at the meeting – and the geologists I worked with in the field – will now see burrows long overlooked in the past.
Here’s one of my favorite pics of fossil burrows. It’s from a site in Nevada, famous for it’s well-studied sedimentary layers. I talked with a grad student researching there and she, like many other people, hadn’t even realized her site was FULL of burrows!
This is my labmate, Carlie. Behind her, the dark colors highlight the burrows that permeate so much of these sedimentary layers. Burrows – they are all over the place! They tell us a lot about the environment – The diversity and abundance of animals, oxygen levels, all that good stuff. So, after a mass extinction, obviously I’m keeping my eyes out for burrows of sea floor animals.
August 15, 2012
A friend requested more posts and photos about fossils! I will deliver. Why have I posted so few? Below, I explain my two pragmatic reasons.
But first, a fossil! Let’s make this interesting. Take a look and give me a guess what you think this image shows. Post your guess in the comments so everybody can see. Don’t worry, there are no silly guesses – this is how paleontology became what it is today. We learn to reexamine rocks and every year realize there are amazing records of past live we’ve overlooked for centuries!
Specifically, check out the orange-ish parts of this rock. Is this a fossil? If so, of what!? Hints: red and white stripes on the Jake staff are 10cm each. This image is looking at the bottom of a layer of rock. Need more hints? Post questions in the comments, and I should be able to answer in Lima.
Why haven’t I posted pictures or videos of my rocks or fossils here?
1) When lucky enough to have a hotel during field work, my nighttime duties include cataloguing the days observations and samples, looking up information on the internet, and communicating with people back home. This blog is a part of that but it’s all I can do to get one dispatch out most nights.
2) Sadly paleontologists can be very competitive, dishonest people. I vividly remember my first science meeting, 24 years old, two weeks after finishing my first official summer field expeditions. Researchers from three different countries came up to my poster to tell me they planned to fly to the American west to do my dissertation project before I could finish it. This was after I offered to collaborate with people who turned me down! The silver lining here is that I’m studying something people care about. As a totally non-competitive person, though, I just can’t wrap my head around people who lie and manipulate – basic human behaviors to which, sadly, science is not immune. Consequently, I don’t so much as post on Facebook about where and when I do field work, and what fossils I find. I post pictures of sunsets and lizards, weeks later. Because my main dissertation research isn’t published yet, I can’t even describe exactly what I’ve found and why I’m here openly on the internet.
To be fair, though, there are plenty of rocks and fossils I’ve seen on this trip that are plentiful throughout time. They won’t, you know, spill the beans. So, insofar as I have time, I’ll post pics and explanations of cool fossils or features over the next week or so.
Right now time is short – I still have a sack of specimens to re-catalogue and most of my gear is packed, then we head down the mountain for Lima, a drive of 4-5 hours. Wish us luck!