SciCafe: Hidden Reptiles of Madagascar

Thursday, May 26 2:17 pm

After more than 200 years of exploration, new species of snakes, chameleons, geckos, and skinks are still being discovered in Madagascar, the fourth-largest island in the world. At the next SciCafe on Wednesday, June 1,  Christopher Raxworthy, associate curator in the Department of Herpetology who has spent decades working in Madagascar, will discuss the mix of modern technologies—including satellite imagery and DNA sequencing—and “muddy boots” field biology to remote parts of the island that is making discovery possible today.

In this video, produced in 2010 and shot partly in the field, Raxworthy describes surveying chameleons in Madagascar.

Author Q&A: Driven To Extinction

Tuesday, April 19 11:18 am

For over a decade, Richard Pearson, a scientist at the Museum’s Center for Biodiversity and Conservation, has studied how climate change is affecting ecosystems around the world. Now he has written a book, Driven to Extinction: The Impact of Climate Change on Biodiversity, which highlights current threats and points to strategies for conservation. Pearson, who will be discussing his book at the Tribeca Barnes and Nobles on Thursday, April 21, recently answered a few questions about his work.

Can you describe your research at the Museum?

I study the distributions of species: Where are certain species found? Why are they found where they are? And how do distributions change over time? Of course, one of the factors that causes distributions to change is climate.

Can you give an example of how climate change affects species distribution?

One example comes from research that we have undertaken here at the Museum.

We’ve used data from expeditions and from the Museum’s collections to show that species of amphibians and reptiles in Madagascar have shifted their ranges upslope as the climate has warmed. This is one of the traits we expect to see due to climate change: species move upslope to locate cooler conditions as the temperature warms.

What are some of the methods used to make predictions about the impact of climate change?

One of the most common approaches is to build computer models of natural systems and to then change the parameters to mimic climate change. This is one of my main areas of interest and is the focus of much of my research. Of course, computer models are abstractions of the real world but they can be very useful tools for improving our understanding of what the future may hold. In the book, I describe how the models work and I try to be very clear about what they are good at and what they are missing. Read more »

Golden-Colored Spider Silk On Display Through October 3

Friday, September 03 8:57 am

Spider Silk. Credit: AMNH\R. Mickens

Time is running out to view what took four years, some 80 people, and over one million golden orb spiders from Madagascar to create: an 11-by-4 foot, naturally golden-hued textile on display in the Museum through October 3.

For more than 100 years, people have tried to extract silk from spiders, but the spectacular, rare fabric showcased in the Museum Grand Gallery is the only surviving textile made out of the silk of these hairy, eight-legged creatures.

“I was blown away by its wonderful, lustrous, golden color,” says Museum Curator Ian Tattersall. “Only one other spider silk textile was ever exhibited, in Paris around 1900, and that has subsequently been lost, so this is unique in the world” (To hear more from Dr. Tattersall on the spider silk exhibit, go here).

Golden orb spiders—the largest of which can grow to the size of a human hand—produce golden-hued silk that is stronger than steel but is conveniently elastic and lightweight. Because of these rare properties, people have envisioned potential applications for spider silk in battle, surgery, and space exploration, among other fields. But unlike silkworms, which can be easily farmed to produce mass quantities of silk, golden orb spiders are cannibalistic in nature, making them difficult to hold in close quarters and to extract silk filament in big quantities.

Despite the obstacles, American fashion designer Nicholas Godley teamed up with art historian and textile expert Simon Peers to build a complex spider silk harvesting operation in Madagascar. The pair hired locals, who collected over 3,000 spiders per day by using long bamboo sticks to tear down the spiders’ golden-colored webs, which can span the length of a one-lane road. Read more »

Dinosaur Demoted: New Fossil Material Re-Defines Azendohsaurus

Wednesday, May 19 10:35 am

A reconstruction of the skull of the new species of Azendohsaurus. Credit: Sterling Nesbitt

Azendohsaurus just shed its dinosaur affiliation, according to a team of researchers that includes the Museum’s John Flynn. But in doing so, it “ends up being a much more fantastic animal than if it simply represented a generic early dinosaur,” says André Wyss, one of the authors of the new paper published in Palaeontology.

A careful new analysis of a 230-million-year-old Azendohsaurus fossil found more than a decade ago in Madagascar, A. madagaskarensis, aligns this animal with a different and very early branch on the archosauromorph reptile evolutionary tree (the group that includes living birds and crocodiles). This means that the plant-eating adaptations of Azendohsaurus, similar to those found in some early dinosaurs, developed independently, and that herbivores were much more common among archosauromorphs than had been previously thought.

“As we found and analyzed more material, it made us realize that this was a much more primitive animal and that the dinosaur-like features were really the product of convergent evolution,” says John Flynn, a paleontologist at the Museum.  “Even though this extraordinary ancient reptile looks similar to some plant-eating dinosaurs in various features of the skull and dentition, it is in fact only distantly related to dinosaurs.”

For more information, see the official press release, the current research article, and the initial article in Science.

Chris Raxworthy Finds Chameleons in Madagascar

Friday, March 05 4:48 pm

With Madagascar containing nearly two-third’s of the world’s chameleon species, Christopher Raxworthy, Associate Curator of Herpetology at the American Museum of Natural History, recently embarked on an expedition to the island in search of these special lizards. His hope was to track down the lined-chameleon in order to further study speciation on Madagascar.

Having recently returned from Madagascar, Raxworthy brought back video footage of his research trip to give everyone a glimpse into his studies and what life is like for scientists in the field, including camping in remote villages, searching for specimens in the jungle and traversing the varied island landscape.

Raxworthy first visited Madagascar in 1985 and has returned most years since, making this recent trip upwards of 20 expeditions to the Indian Ocean island — the fourth-largest island in the world.

While Raxworthy’s recent findings must remain in Madagascar until the end of this current collection season, once he has the chameleon specimens at the Museum his work to classify and study the DNA will begin.