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NOVA ScienceNOW

Trapped in Amber

  • By Peter Tyson
  • Posted 05.01.09
  • NOVA scienceNOW

George Poinar has found evidence in fossil amber that diseases like malaria might have plagued the dinosaurs, even helped force them into extinction. In this audio slide show, Poinar guides you through a gallery of fossil plants and animals, some containing disease microbes, that have been preserved for millions of years in amber.

Launch Interactive

In this audio slide show, George Poinar guides you through a gallery of fossil plants and animals.

Transcript

Trapped in Amber

Posted: May 1, 2009

GEORGE POINAR: I'm George Poinar, and I'm currently working in the Department of Zoology at Oregon State University.

I've been studying amber for about 40 years, and my interest has been in all types of life forms in amber, from plants to animals, including vertebrates and invertebrates, and all the way down to microorganisms.

Here we have a beautiful planthopper. And this is a wonderful thing about amber, is that it preserves organisms in three-dimensional form.

Just looks like, for instance, a bee or a leaf fell into the amber yesterday. And you can see it. You can study it. You can turn it around.

One of the reasons to collect these fossils, all types of fossils, is that you can use them to reconstruct ancient environments.

This was a humid-type forest, and it probably formed between 15 and 30 million years ago.

Here we have a petal of the algarrobo tree, which is a tree that produced the resin that eventually turned into amber. All parts of this plant produced resin. And after the amber fossilized, it became harder, and then, eventually, it had the properties of what we now call amber.

Here you can see one of the stamens, which has fallen out of the flower and landed on the resin, and the impact released all the grains of pollen that were in the anther, and so you have this cascade of beautiful pollen grains.

Sometimes we can determine the plants that occurred back then, 20 to 30 million years ago, on the basis of insects found in the amber that are specific to particular plants.

Here, we have a remarkable fig wasp. These only develop in figs, and they're the sole pollinators of figs. So when we find the fig wasp, we know that there had to be figs in the original forest. And this fig wasp was especially interesting because it was carrying a group of nematodes, these very small, thin roundworms.

Here we have an ant and a wasp together in a piece of Dominican amber. This happens to be an army ant, and the wasp pupa that it was carrying is probably its prey, and it was carrying it back to the nest. And so here, we have not only evidence of army ants in the ancient forest, but also we know something about what was going on between ants and wasps.

There's a number of vertebrates that also got entwined in the resin. And here we have a gecko, a beautiful gecko. It's associated with a leaf, and it's completely entombed in the amber. The detail is marvelous.

We've never found any complete birds in amber. We've found some bird feet. We've found some bones. We've even found a small hummingbird egg in Dominican amber. And we've found feathers. This feather was identified by experts at the Smithsonian Institution as coming from a piculet, a type of woodpecker.

Mammals are very difficult to find. A few bones have been found, but usually it's the hair. Here, we have the hair of a rodent, probably a hutia. This is a South American rodent that still occurs today and spends a lot of its time up in the trees.

After we finished our book on the Dominican amber forest, my wife Roberta and I turned our attention to some of the more ancient amber from the Cretaceous period. We've always been fascinated with this older amber because it was formed during the period of the dinosaurs.

And here we have a mosquito that's approximately 80 million years old. We felt that there may be some clues in the amber, which would tell us how insects interacted with the dinosaurs, and even perhaps how insects may have affected the demise of the dinosaurs.

We were especially interested in the vectors. The first one we found was a sandfly, in amber, 100 million years old. Sandflies are well-known for vectoring leishmania today. And in the proboscis of the sandfly, we could see stages of the leishmanial parasites. These are the stages that developed in the vertebrate.

And then in the gut of the sandfly, we could see separate stages, forms that developed in the sandfly, and we could compare them with present-day leishmania carried by sandflies to humans. We feel that the dinosaurs were definitely infected with leishmania.

Now, everybody knows about ticks. And here we have one of the oldest known ticks ever. This tick is a larval stage. See? It only has six legs. These ticks, we feel, certainly fed on dinosaurs. And if you look today at all the things that ticks can carry and pass on to vertebrates such as viruses, protozoa, bacteria, and nematodes, then you'll realize that the dinosaurs had these to cope with as well.

Here, we see a biting midge. These attack all kinds of things today. They take blood. We were fortunate enough to find one 100 million years old, which was carrying an ancient malarial parasite, Paleohematotropis. You could see the stages actually developing in the body of the biting midge. And so we feel that, again, this was a disease that the dinosaurs had to cope with back in the Cretaceous.

And we feel that these diseases and others played an important part in the decline of the dinosaurs.

Credits

Audio

Produced by
Peter Tyson
Edited by
Rachel Vancott

Images

(George and Roberta Poinar)
© Courtesy Dan Wise
(all others)
© Courtesy George Poinar

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    An astonishing adolescent growth spurt accounts for T. rex's enormous size.

  • The Four-Winged Dinosaur

    Surprising fossils from northeastern China spur a debate over how birds evolved.

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