Category Archives: Research

The Breaks local fauna and North American Land Mammal “ages”

Many years ago, I wrote a dissertation. That was the final step toward my ultimate goal of becoming a ‘real’ paleontologist. My research was strictly biostratigraphy: putting rocks and fossils in order by age from oldest to youngest. Specifically, I was looking at mammal fossils from the middle of the Paleocene, about 60 million years ago.Continue reading “The Breaks local fauna and North American Land Mammal “ages””

The Paleocene-Eocene Thermal Maximum – Is Modern Global Warming Anything to Worry About?

There are lots of names for it, some good, some bad: Climate Change, Global Warming, Climate-gate, The Climate Hoax. Unless you’ve had your head in the sand, you’ve heard at least one of these things. You know that there is a lot of talk about how every year seems to be warmer than the last – “the warmest on record” – and that there have been a lot of wacky weather phenomena of late, including Hurricane Sandy, heat waves in Australia and Europe, massive wildfires in the western United States. Some reports are pretty alarmist, while others claim that these are merely coincident anomalies that we only know of due to more complete modern measuring techniques and records. Some say that the Earth is warming at an alarming rate and we need to prepare for a “The Day After Tomorrow” type scenario, while others say that we have no need to worry and that it’s all hype. And really, how bad can one or two degrees of temperature increase be?

If you’ve read other posts of mine, you probably know where I stand on this. For this post, my views on the legitimacy of modern global warming are irrelevant. What I want to address here is not whether warming is occurring, but what would happen if those noisy scientists are right and we are heading toward a warmer Earth? What could the possible outcomes of a few degrees of warming be? There are models, of course, all mathematical and computerized, that show where things will get wetter or drier and such, but let’s think about something more real.

What if the hype is correct and we are warming? What will happen if we do nothing to mitigate it?

The fossil record provides an opportunity to look at past climate changes and see what effects these changes had on the animals that were alive during that time. The fossil record shows that there have been multiple episodes of global warmth in Earth’s history, much warmer than is projected as a possible outcome of today’s warming. But being warm and warming rapidly are two different things. Gradual warming occurs slowly enough that organisms can adapt. But modern warming is occurring within a single to just a few generations of animals, much too quickly for adaptation to occur. What happens then?

Does the fossil record capture any past episodes of rapid global warming? If so, what happened?

The short answer is ‘yes,’ and it was bad news for many animal groups.

The specific example I will use is the Paleocene-Eocene Thermal Maximum (PETM). This is an episode of global warming that occurred about 55 million years ago (about 10 million years after the dinosaurs went extinct). The entire PETM lasted 150,000 to 200,000 years, with the warming occurring over the span of about 10,000 years. Depending on what you read, the warming was between 5-9° Celsius (9-16° F). Compare that with modern projections of warming of 4° Celsius (or more) in a few hundred years. Warming rates are much faster today than they were at the PETM, and rates at the PETM were much, much faster than most other rates of climate change recorded in the rock record.

The warming associated with the PETM is particularly interesting for two reasons. 1) It’s thought that the warming was due to an increase in carbon dioxide in the Earth’s atmosphere, much like today’s warming. 2) Mammals were around then, and the dominant large-bodied animals living on land. We can look at the record of change in mammals at the PETM as an analogue for what might happen if modern global warming is ‘true.’

So, what happened?

Changes in vertebrate taxa at Polecat Bench, Bighorn Basin, Wyoming. © Philip Gingerich, 2006

The chart above shows a lot of things. It was published in 2003 in Geological Society of America Special Paper 369. It is available here, from Philip Gingerich’s personal web page focusing on his research on the PETM. I suggest reading the entire paper to get the full context, but for the sake of this post focus only on the columns on the right hand side. There are two columns labeled ‘stable isotopes,’ and a series columns (some highlighted in green and others in red) that represent the stratigraphic ranges of specific vertebrate groups. The heavy red line marks the Paleocene-Eocene boundary, and the box in the stable isotope column encloses the isotopic evidence of the PETM – a negative spike in carbon isotopes and a positive spike in oxygen isotopes. It is the positive spike in oxygen that provides the evidence of warming. The negative spike in carbon provides information about the source of the warming (carbon dioxide in the atmosphere). The details of how the isotopes provide such information is a topic for a different blog post.

Focus now on the highlighted vertebrate groups. In green are the Plesiadapidae. Plesaidapids are a group of mammals thought be closely related to modern primates. They go extinct at the Paleocene-Eocene boundary. Modern primates, highlighted in red, appear after the Paleocene-Eocene boundary. It’s possible, then, the the PETM, was responsible for the extinction of the the plesiadapids and appearance of modern primates. Perhaps one evolved into the other, we are not sure at this point, but the loss of one and appearance of the other coincides with the PETM.

You also see, highlighted in red, the first appearance of the groups Perissodactyla and Artiodactyla. These are all the modern hoofed mammals. (Perissodactyla includes horses, rhinos, and tapirs. Everything else is in the Artiodactyla.) It is the appearance of the first perissodactyl, Sifrippus (also called Hyracotherium or Eohippus) that defines the beginning of the Wasatchian North American Land Mammal “age” which is thought to be coincident with the Paleocene-Eocene boundary. Prior to the PETM, there were no true hoofed mammals, though it’s though that the ancestors to perissodactyls and artiodactyls could be found in a group of mammals loosely called the condylarths. Condylarths dwindled after the PETM, to be replaced by the recognizable, modern groups of mammals.

Thus it’s possible that rapid global warming at the Paleocene-Eocene boundary resulted in the rapid evolution of mammalian species, resulting in the loss of many groups that had previously been dominant, and their replacement with new groups. This is a big change. This is not an example of just a few species going extinct. We’re talking about entire orders of mammals here, including the Order Primates, of which we are a member.

Now consider again that warming at the PETM took place over several thousands of years. Modern global warming is occurring over several hundreds of years. If warming at the PETM forever altered mammalian history, what would modern global warming do? Perhaps we should think about this before we say that there’s no need to be concerned.

***UPDATE***

This post has been translated into Spanish by Jorge Moreno-Bernal, a student at the University of Nebraska-Lincoln.  See the translation here. How cool is that?

An Interview with… me!

I was recently interviewed by Gary Vecchiarelli for a lovely website called Jersey Boys Hunt Dinosaurs. He was particularly interested in my take on the science of paleontology from the perspective of a geoscientist.

It was a fun little interview, and might be of interest to any budding paleontologists or folks just interested in what my scientific world is like. Read the interview here.

You should visit the Jersey Boys Hunt Dinosaurs website and/or follow them on Twitter.

Thanks Gary! That was fun!

An Isotopic Study of Lake Effect Snow

I’ve written a few blog posts about what can be done with isotopes from precipitation, and how that might assist us in understanding how to interpret isotopic data collected from ancient rocks and fossils. (Look here and here.) As I live here in western New York state, close to Lake Ontario, I frequently have opportunities to further study how the isotopes from precipitation (in this case Lake Effect snow) are related to the isotopes of the water that originally evaporated to make the clouds that do all the snowing.

Right now, we’re looking at a Lake Effect snow event that’s due to start sometime tomorrow, so I’m throwing together is quick and fun isotopic study that I’ll share with you when the data come in. I’ll describe it here.

As review, let’s think about isotopes in water. First, what do I mean by isotopes? The term worries people, because they immediately think of radioactive isotopes and OMG, we’re gonna die! No, it’s not like that. The word isotope just refers to the fact that some atoms of the same element are heavier or lighter than the others.

Water is composed of hydrogen and oxygen (H2O). Hydrogen comes in two types. Most of it has a mass (think of it as weight) of 1. Some of it has a mass of 2. (The hydrogen with a mass of 2 is called deuterium. It’s one of the few isotopes that has its own name.) So water is mostly made with hydrogen atoms of mass 1, but some water has hydrogen of mass 2. The water with the mass 2 hydrogen is heavier than the water with the mass 1 hydrogen.

Similarly, oxygen comes in two important isotopes. The most common form of oxygen has a mass of 16. A more rare (but not radioactive) form of oxygen has a mass of 18. Either type of oxygen can be in a water molecule, but the water with the mass 18 oxygen is heavier.

With mass spectrometry, we can measure water to see how much of it has the heavier hydrogen and the heavier oxygen. This is what I do for a living.

To get any kind of precipitation (rain or snow), water must first evaporate to make a vapor mass in the atmosphere. You can think of this as just making a cloud or a storm. In the case of Lake Effect precipitation, the water that’s evaporating is the lake itself. When the water evaporates, the lighter water evaporates more than the heavier water because, well, it’s lighter. So the cloud that you get from evaporation is isotopically lighter than the lake it evaporated from.

We measure ‘lighter’ or ‘heavier’ with isotopes using what we call ‘delta notation.’ The numbers we get are given in ‘permil’ (‰) even though they’re not a concentration. What’s important is that more positive delta values means that there’s more of the ‘heavy’ element. More negative values means there’s more of the ‘light’ element. So, if the lake has a delta value of -1‰, then the cloud should have a more negative value, like -3‰. When a cloud rains or snows, the heavier elements fall out first, because they’re heavier. If the cloud has an isotopic value of -3‰, the snow should have a more positive value, like -2‰.

The change between lake and cloud, or between cloud and snow, is called fractionation, and is controlled in part by temperature. (This means that the numbers I just gave you are completely made up.) The fractionation is also different for hydrogen and oxygen, and we measure these separately. (Hydrogen and oxygen isotopes in water do tend to vary together, but it can get pretty complex.)

As a cloud rains, it loses its heavy isotopes. If we take a cloud or storm (or say a hurricane) and take it from its water source (a lake or the ocean) and move it over land, this fractionation will go on. If no more water vapor is added, then the cloud gradually gets isotopically lighter. This means that the precipitation will also get lighter (but will always be heavier than the cloud). This process is called ‘Rayleigh Distillation,’ and is an important assumption in isotope geochemistry. Luckily, it has been shown to be a good model.

All right, let’s get back to Lake Effect snow. We’re looking at a Lake Effect event that is expected to start sometime tomorrow. We can get snow bands off of the lake that make great stripes of snow across the landscape.

What Lake Effect snow from Lake Ontario teach us?

We know that the snow will be forming from water evaporated off of Lake Ontario, so it will be useful to know the isotopic values of that water as a baseline. We have no way of measuring it isotopic values of the water vapor (the cloud) but we can find out the air temperature close to the lake surface and calculate the the isotopic value should be.

Then, we can measure the isotopic value of the snow that falls. We can collect snow that falls right at the lake (that which first forms from the freshly evaporated water) and we can look at snow that falls some distance away. We can make predictions about what patterns we might see.

Predictions:

1) Snow collected near the lake will be isotopically heavier than snow collected further away. Even though it’s only a few miles, Rayleigh Distillation should have some effect.

2) Over time, the snow collected at one location should not change in isotopic value, unless air temperature at the lake varies significantly. Because the cloud will be continuously replenished from Lake Ontario, I don’t expect to see any variability over time. The isotopic value of the lake water should not change consequentially. What can change is the air temperature, which will alter the fractionation of the isotopes (when it’s colder, less of the heavy water will evaporate). Also, colder temperatures could result in freezing of the lake surface, effectively moving the shoreline further into the lake.

It’s a pretty simple thing to test these predictions. I just need to collect some snow samples (and recruit other people to do the same). Specifically, I’ll be collecting every six hours, since I’ll be measuring snow depth at that time interval anyway. Collecting every twelve hours would probably be sufficient. I run a laboratory that has a liquid water isotope analyzer, so analysis will be easy. Once I’ve got the results, then it’ll be a quick write-up that everyone can benefit from here. It’ll be interesting to see how well my predictions hold.

Our water analyzer, Norm, analyzing waters from hurricane Sandy.
Our water analyzer, Norm, analyzing waters from hurricane Sandy.

If you live nearby and think you might be interested in helping out with this little project, let me know in the comments below. The more the merrier!

UPDATE 1-21-13

After waiting for 24 hours, there has not yet been any snow. But I’m assured it’s on the way!

UPDATE 1-22-13
Snow is falling. Finally.

 

Overly Honest Methods

If you’re familiar with Twitter, you’re familiar with the concept of the ‘hashtag.’ A hashtag is used to mark a tweet so that it can be collected with tweets on a similar topic. For example, there’s a new television show coming out called “The Following.” If I want to see what other people are tweeting about The Following, I just look for the hashtag #thefollowing. The pound symbol at the front of the tag is what distinguishes it as a hashtag.

When I teach, I devise a hashtag for my class: #UREES101 for the introductory geology class and #UREES207 or #UREES270 for my upper-division paleontology courses. Students can use the hashtags to tweet questions and answers (or whatever they want) that’s related to the course and anyone who searchs for the hashtag can find their tweets.

The other day a hashtag was started that’s been a delight to follow: #overlyhonestmethods. People using this hashtag post about the scientific methods and techniques used in their research, as if they were writing them up for a professional paper, but being totally honest about why they did what they did. You can look at the posts here, through tweetchat. You don’t need to have a Twitter account to enjoy them.

There are a couple of good blog posts already out there too:

POPSCI

io9

Here are my own contributions:

 

 

 

The main reason why these are so funny is that there is truth in all of them. Yes, there was a globetrotting postdoc in our lab for a while, and washing shave cream from beard hairs is no fun.  That data was never published, but if it were published, we’d find a better way to describe why we selected our sample subject.

It’s also true that we use 14 injections because it worked, and I didn’t want to keep fiddling with the method. I would probably leave out the last bit about being tired of messing with the water analyzer.

So many things that go on in labs are done for convenience. But, that does not make the science wrong. We always outline what exact our methods were. If the eyeballs sat in the drawer for 18 months, we report that. We just leave out the bit about how we forgot about them.

We lay out what we did, not necessarily the ‘why,’ unless it would have a profound effect on our results. It doesn’t matter that we had a convenient traveling postdoc. All we do is report that there was a human subject who had to shave anyway. Who cares if it’s 14 or 5 injections? When we run our analyses, we get the same results as other labs. We’re good.

What #overlyhonestmethods provides is a tongue-in-cheek behind-the-scenes look at what life as a scientist is really like. Some of the posts are clearly jokes, others are absolute truth. But all reflect the reality, and fun, of being a scientist!

What does it take to become an expert?

I’m a member of Litopia, a self-proclaimed “Writer’s Colony” on-line. It’s actually a great place to go and hang out with other writers and learn the trade.

Recently, a discussion thread came up about what it takes to become an expert. It was linked to this post.

Importantly, it made the point that the transition from novice to expert was marked by preferentially focusing on negative feedback over positive feedback.

Here was my reaction:

Expertise is a funny thing. For me, in my field (which is isotopic analysis of tooth enamel from fossil mammals), becoming an ‘expert’ isn’t something that I sought to do. I just wanted to do the best I could because my own research depends upon this kind of analysis. I don’t feel like an expert – I know that there’s tons of room for improvement. (But maybe this goes to the point about how experts focus on the negative more than the positive.)

But one day, about a year ago, it happened. I got the first e-mail I’d ever gotten that said something to the effect of “We have these enamel samples that need analysis, and we’ve heard you’re the best.” After I scraped my jaw off the floor, I told them that I could analyze their samples and there you go… Since then I’ve gotten similar e-mails from people all over the world and from students who want to study with me.

I guess I’m an expert.

What makes me an expert? Getting out there and getting noticed is important. So, not all experts are introverts. I mean, I guess I could be an expert and introverted, but who would know? What would it get me? Naw, I get out there, go to meetings, use Twitter and blogs, and talk about what I do. Other people notice and they decide I’m an expert.

Maybe being an expert isn’t something that you decide. Maybe it depends upon the perceptions of other people. And if enough other people – especially those that you yourself would call experts – are calling you an expert, maybe it’s true.

I’m all right with that.

I can haz career?

National Blog Posting Month – December 2012 – Work

Prompt – Do you think you have a job or a career?

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To me, having a ‘job’ would be working for an hourly wage at something that you do only for the pay and not because of any long-term goal. ‘Jobs’ are typically positions that do not provide much (if anything) in the way of benefits or retirement plans.

A ‘career’ involves working at a single type of work (hopefully at a single place of employment) with a long-term goal of working up to higher positions and greater pay and usually includes some manner of retirement plan.

Most definitely, I have a career. It’s hard not to have a career when one has put the time into getting a Ph.D. (though it happens). I expect to be doing the same sort of work (science and teaching and maybe a little writing) until I’m ready to retire.

Further evidence that I have a career: I finally got business cards. I feel all grown up.

Back off, man! I'm a scientist!
Back off, man! I’m a scientist!

For 12-26-12