They are some of the rarest of rare artifacts: fossil dinosaur eggs with the embryo still inside. And they are prized for what they can tell paleontologists about the adults that laid them.

The exhibition The World’s Largest Dinosaurs features a scale model of a nest found at Auca Mahuevo, Argentina, one of the largest known dinosaur nesting sites in the world. While it isn’t always possible to figure out which dinosaur laid a particular egg, in this case, an embryo within an egg found at Auca Mahuevo site allowed scientists to identify these eggs as those of titanosaurs, a group of sauropods that included such species as Ampelosaurus and Saltasaurus. Herds of female titanosaurs are thought to have laid the thousands of eggs — 15 to 40 at a time — in shallow nests dug out with their huge feet in dry mud and sand over miles of ground at Auca Mahuevo.

Blogging from west Kenya, William Harcourt-Smith, a research associate in the Division of Paleontology, is directing a 20-million-year-old paleontological site on two islands in Lake Victoria. One of these islands, Rusinga, is best known as the site of the discovery of the first fossils of Proconsul, an early ape. Harcourt-Smith’s multidisciplinary team includes physical anthropologists and geologists, and in addition to collecting fossils, researchers are trying to learn more about the evolutionary events and environmental conditions that may have influenced the emergence of Proconsul and other early ape lineages.

Blogging from west Kenya, William Harcourt-Smith, a research associate in the Division of Paleontology, is directing a 20-million-year-old paleontological site on two islands in Lake Victoria. One of these islands, Rusinga, is best known as the site of the discovery of the first fossils of Proconsul, an early ape. Harcourt-Smith’s multidisciplinary team includes physical anthropologists and geologists, and in addition to collecting fossils, researchers are trying to learn more about the evolutionary events and environmental conditions that may have influenced the emergence of Proconsul and other early ape lineages.

Fossil preparation requires an uncommon degree of adaptability and patience. Museum preparators bring to the task diverse sets of skills from such backgrounds as art, paleontology, and archaeology. They generally learn their craft on the job, drawing from related fields such as object conservation to adapt modern glues, solvents, and other archival materials to stabilize fragile areas or repair damage.

Watch as Justy Alicea, a preparator at the American Museum of Natural History, works on a specimen and offers a tour of the Museum’s fossil preparation lab. And for more about fossil preparation, read this story, which originally appeared in the Summer 2010 issue of the Members’ magazine Rotunda.

The World’s Largest Dinosaurs, a new exhibition at the American Museum of Natural History, goes beyond traditional fossil shows to reveal how dinosaurs actually lived by taking visitors into the amazing biology of a uniquely super-sized group of dinosaurs: the long-necked and long-tailed sauropods, which ranged in size from 15 to 150 feet long.

In this video, go behind the scenes with The World’s Largest Dinosaurs curators Mark Norell and Martin Sander and as they explain the science behind the exhibition. Learn how dinosaur fossils are stored and cataloged from Carl Mehling, a scientific assistant at the Museum.