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The Discovery of the Pterosaur Tropeognathus

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There is a place called the Araripe Basin in a remote, sparsely populated region of northeastern Brazil. Arid but beautiful, it can be a difficult place for farmers to grow crops.

Alexander Kellner

Alexander Kellner at the Araripe Basin, Brazil


But the earth provides another bounty: fossils. And among the bevy of bones are some rare finds—including 23 species of extinct flying reptiles called pterosaurs. More than three decades ago, a local there found some large pterosaur bones. He delivered them to the Museu Nacional in Rio de Janeiro, where they were tucked away in a drawer. As it happens, many natural history museums have a trove of unexamined fossils awaiting study in their collections—there are just too many to go through.

But a few years ago, paleontologist Alexander Kellner, a research associate at the American Museum of Natural History who as a doctoral student trained with Curators John Maisey and Malcolm McKenna, found the time to examine the 30-plus-year-old fossil finds at the Rio museum, where he is now a curator.

Before studying the bones, Kellner had to dissolve the calcereous “nodules” of rock in which the bones were entombed by sinking the fossils into buckets of formic acid. Using a pneumatic hammer, specialists at the museum gradually freed a partial skeleton of the animal from its stony home.

It included part of the animal’s skull, complete with a bony crest at the tip of its nose, vertebrae, pelvis—and, perhaps most dramatically, arm and wing-bones.

Tropeognathus pterosaur

This model of Tropeognathus mesembrinus, a 110-million-year-old pterosaur species with a wingspan of more than 25 feet, hangs over the entrance gallery of Pterosaurs: Flight in the Age of Dinosaurs.

© AMNH/R. Mickens


The wingspan of this pterosaur was, the research team concluded, nearly 27 feet—the largest pterosaur discovered so far in the Southern Hemisphere. A model of this recently described giant specimen, from the species Tropeognathus mesembrinus, flies overhead at the entrance to the special exhibition Pterosaurs: Flight in the Age of Dinosaursoverseen by Curator Mark Norell with Kellner as co-curator.

Read more about pterosaurs and the exhibition here.

Purchase tickets to the exhibition here.

This article is excerpted from a story that appears in the Spring 2014 issue of Rotunda, the Member magazine.

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