Senckenberg up close

A big and very challenging puzzle

Interview with Dr. habil. Krister T. Smith

How does climate (change) influence ecological cycles and what can fossils teach us about the climate of past times? Paleontologist Krister Smith is fascinated about the roots of life. In this interview, he explains the origins of his excitement for Paleoherpetology and sheds light on the secrets hidden in the Messel Pit.

Why did you decide to become a scientist?

Honestly, I wasn’t even aware that one could become a scientist – that is, a professional – outside of a company or hospital until I was at university. There, I once asked a graduate student how many jobs there are in paleontology, and he answered: “There aren’t any.” An exaggeration, to be sure, but it’s true that there are many more people with degrees in paleontology than there are paleontologists. Still, I had already been “bitten by the bug,” I was stubborn and ultimately lucky.

What do you find especially fascinating about Paleoherpetology?

I am fascinated by the roots of things; I want to know where they come from. Lower vertebrates are highly diverse – there are over 10,000 living species of squamates, that is, lizards and snakes! They are also difficult to study. Unlike in mammals, say, you can’t just pick out jaws from an assemblage and identify species. You have to put the whole skeleton, or at least the skull, back together. It’s a big and very challenging puzzle. And I like a challenge.

What specific question are you currently researching and which methods do you use? I’ve worked a great deal on limbless squamates over the past year or so. Many groups of squamates have lost their limbs, and snakes are the best known of these groups. Particularly in the early part of the Cenozoic, the last 66 million years, many fossil species have been described based on isolated bones from different localities. In reality, they may have names, but we know almost nothing about them. Some colleagues and I are shedding light on these limbless animals – on the early stages of their evolution, how they lived, how their communities were structured, and how they interacted with their environment (such as infrared vision). 

How can fossils of Squamates be used to draw conclusions about the climate of past times?

This is one of the broad-scale questions that motivates most everything that I do, from alpha taxonomy to systematics to taphonomy. If you have a relatively young fossil assemblage – say, from the last couple of million years – it is likely that many of the species are extant, and the simplest way is to look at the climatic preferences of those living species. Those conditions under which all of these can co-exist today gives you an indication of the climate under which that assemblage was deposited.

What if you’re working with extinct species?

In this case, things get tricky. You have to incorporate the evolutionary tree, because it links all species, living and extinct.

What scientific methods do you use in your research?

We apply modern methods like computed tomography to the exquisite fossils of the Messel Pit, and we combine this with detailed morphological studies of specimens from other localities throughout Europe.

Speaking of Messel: The Messel Pit gives an insight into the Eocene climate optimum, the warmest sustained time interval of the past 66 million years – can findings about the animal and plant communities of that time tell us something about the future of our warming planet?

Messel is one of the most extraordinary fossil assemblages we know of. It is extremely rare for a single assemblage to preserve so many components of an ecosystem: plants, fungi, mollusks, arthropods and vertebrates. That’s a huge proportion of macroscopic life! Messel even preserves records of organismic interactions, as some pretty spectacular fossils have shown. Thus, the Messel Pit holds – perhaps uniquely – the promise to understand how an ecosystem functions under the climatic conditions that we may experience in the next 200 years, or sooner.

The Eocene is not only extraordinary because of the high average temperatures, but also because of the sudden increase of global temperature by approx. 6 ° C about 56 million years ago. What do fossils tell us about how flora and fauna reacted to this change in temperature?

That event, the Paleocene-Eocene Thermal Maximum, has been studied in great detail by many people. Our picture of it is not by any means global, but it’s improving. Some general trends stand out.

What kind of trends?

First, large-scale range-shifts take place. Warm-adapted lineages move northward in the northern hemisphere. As high-latitude corridors open up, dispersal of many lineages between continents takes place – “invasive species”, we’d call them today.

Second, in some cases on land there is a local increase in species diversity, and in the intensity of organismic interactions. It’s important to recognize, however, that the regional picture of species diversity is generally lacking, and in other cases, like the oceans, extinction events are documented.

Third, some lineages experience a change in body size – “dwarfing” – associated with higher temperatures, following a well-known ecological rule.

One thing is for sure: ecosystems were utterly transformed by this event, the course of history forever altered.