Roy Chapman Andrews and the Gobi Dinosaur Eggs of 1923

The discovery of the Gobi dinosaur eggs in 1923 was one of the most celebrated moments in the history of palaeontology. On 13 July 1923, members of Roy Chapman Andrews’ Central Asiatic Expedition found clutches of fossil eggs at the Flaming Cliffs in Mongolia, the first eggs widely recognised as having been laid by dinosaurs. The finds made Andrews an international celebrity and opened the Gobi Desert as one of the world’s richest dinosaur regions.

Background: the Central Asiatic Expeditions

Roy Chapman Andrews (1884–1960) was an American naturalist from Beloit, Wisconsin, who had joined the American Museum of Natural History in New York in 1906. By the late 1910s he had travelled widely in East Asia, and he proposed a large, motorised expedition into the interior of Mongolia.

His most important supporter was the museum’s president, Henry Fairfield Osborn. Osborn believed that Central Asia was the cradle of humanity and hoped the expeditions would find early human fossils there. Andrews raised money from wealthy donors and organised the Central Asiatic Expeditions, which went into the field in 1922, 1923, 1925, 1928 and 1930.

The expeditions were unusual for their time. Andrews used Dodge motor cars to cross the desert, supported by camel caravans that carried petrol, food and equipment ahead of the vehicles. The scientific team included the palaeontologist Walter Granger, the geologist Charles Berkey and the photographer James B. Shackelford.

The Flaming Cliffs in 1922

Near the end of the 1922 season the party was searching for a route in the southern Gobi when Shackelford walked to the edge of a set of red sandstone bluffs. Within minutes he found a fossil skull. The site was called Shabarakh Usu by the expedition; today it is usually known as Bayanzag. Andrews named it the Flaming Cliffs because of the glowing colour of the rocks in the evening sun.

The skull belonged to a small horned dinosaur that Granger and William King Gregory named Protoceratops andrewsi in 1923, in honour of Andrews. Hints of eggshell were noted in 1922, but the team had little time to investigate before winter.

What happened in 1923

The expedition returned to the Flaming Cliffs in July 1923. On 13 July the assistant palaeontologist George Olsen reported that he had found fossil eggs. The team at first treated the idea with some scepticism, but careful excavation exposed several elongated eggs, about 20 centimetres long, lying in the sandstone. Further clutches followed, some arranged in rings.

The rocks of the Flaming Cliffs belong to the Djadokhta Formation, laid down in the Late Cretaceous roughly 75 to 71 million years ago. The environment was arid, with sand dunes and seasonal streams, and the fine sand preserved fossils in remarkable detail.

Because Protoceratops was by far the commonest dinosaur at the site, the eggs were attributed to it. The 1923 season also produced other important finds:

• A small toothless theropod found lying on a nest of eggs, which Osborn named Oviraptor philoceratops (“egg thief, fond of ceratopsians”) in 1924, assuming it had died while raiding a Protoceratops nest.
• The skull and claw of a small predatory dinosaur, named Velociraptor mongoliensis by Osborn in 1924.
• Tiny skulls of Cretaceous mammals, among the best early mammal fossils then known, which showed what the small mammals living alongside dinosaurs looked like.

The eggs and the public

News of the eggs travelled quickly, and the American press treated Andrews as a hero. To raise money for future seasons, the expedition auctioned one egg soon afterwards; it was bought for 5,000 dollars by a donor who gave it to Colgate University. The publicity helped fund the expeditions, but it also encouraged Mongolian and Chinese officials to believe the foreigners were removing valuable treasures.

Andrews wrote popular books about the work, including On the Trail of Ancient Man (1926) and The New Conquest of Central Asia (1932), the official narrative of the expeditions. His image as a rugged explorer in a broad-brimmed hat made him one of the best-known scientists in the United States.

Key people

Roy Chapman Andrews led the expeditions as organiser, fundraiser and public face. He later served as director of the American Museum of Natural History from 1935 to 1942.

Walter Granger was the chief palaeontologist and directed much of the fossil collecting. George Olsen found the first eggs. Henry Fairfield Osborn sponsored the project and named several of the new dinosaurs. James B. Shackelford discovered the Flaming Cliffs site itself in 1922.

Consequences and later research

The expeditions never found the early human fossils Osborn had hoped for. Political tension in the region grew during the late 1920s, as the new Mongolian People’s Republic and Chinese authorities placed increasing restrictions on foreign collecting. After the 1930 season the expeditions came to an end.

The interpretation of the eggs also changed dramatically. In 1993 a new American Museum expedition, working with Mongolian scientists, found a dinosaur embryo inside an egg of the same elongated type at Ukhaa Tolgod, another Gobi site. Mark Norell and colleagues showed in 1994 that the embryo belonged to an oviraptorid, not to Protoceratops. The Oviraptor found on a nest in 1923 had therefore probably been sitting on its own eggs rather than stealing them.

Later discoveries of oviraptorids preserved in a brooding posture over their clutches supported this view. The name Oviraptor, however, remains unchanged under the rules of scientific naming.

Myths and facts

Myth: the 1923 eggs were the first dinosaur eggs ever found. Fragments of what are now known to be dinosaur eggshell were found in southern France in the nineteenth century, but they were not recognised as dinosaurian at the time. The Gobi eggs were the first to be widely recognised as dinosaur eggs.

Myth: Oviraptor was an egg thief. The name reflects a 1924 interpretation that later evidence overturned. The animal was most likely a parent guarding its nest.

Myth: Andrews was definitely the model for Indiana Jones. This is a popular claim, but there is no firm confirmation from the film makers.

By the numbers

Timeline

• 1922, April: The first Central Asiatic Expedition sets out from Kalgan (Zhangjiakou) into Mongolia.
• 1922, September: James B. Shackelford finds a dinosaur skull at the Flaming Cliffs.
• 1923: Granger and Gregory name Protoceratops andrewsi.
• 1923, 13 July: George Olsen finds the first fossil eggs at the Flaming Cliffs.
• 1924: Osborn names Oviraptor philoceratops and Velociraptor mongoliensis.
• 1930: The last field season of the Central Asiatic Expeditions.
• 1993: An oviraptorid embryo is found inside a similar egg at Ukhaa Tolgod.
• 1994: Norell and colleagues publish the embryo, reassigning many of the eggs.

Legacy

The Gobi remains one of the most productive dinosaur regions on Earth. Later expeditions, including the Polish-Mongolian work that uncovered the Fighting Dinosaurs fossil in 1971, built directly on the map Andrews’ teams had drawn. The study of dinosaur nesting grew into a full field of research, culminating in discoveries such as the Maiasaura nesting grounds in Montana.

The expeditions also linked the American Museum to the golden age of fossil hunting that had begun with discoveries such as Barnum Brown’s Tyrannosaurus rex. Andrews’ fossils, from eggs to early mammals, are still studied in the museum’s collections in New York.

Why it matters

The 1923 eggs proved that dinosaurs laid hard-shelled eggs and nested in groups, a basic fact of their biology that had previously been assumed rather than demonstrated. The finds made dinosaurs front-page news and showed how much the deserts of Central Asia could reveal about life in the Late Cretaceous. The later reassignment of the eggs to oviraptorids is also a classic example of how science revises its conclusions when new evidence appears.