Granger was born on November 7, 1872, in Middletown Springs, Vermont, the oldest of five children of Charles H. Granger, an insurance agent, and Ada Byron (Haynes) Granger. Through his father he was descended from Launcelot Granger, who came from England and settled in Newbury, Massachussets, in 1654. As a boy, Walter was deeply interested in the birds and mammals of the region.
In 1890, after two years in the Rutland high school, Granger ended his formal education to accept a job.
Granger's first job was at the American Museum of Natural History in New York City. His first duties were janitorial, but his knowledge of taxidermy soon involved him in the preparation of study specimens of birds and mammals under the supervision of the ornithologist Frank M. Chapman. When in 1894 he was sent with an expedition to collect living specimens from the Badlands of South Dakota, an area abounding in fossil forms, he developed a strong interest in paleontology, and in 1896, on Chapman's advice, he transferred from the museum's department of birds and mammals to the department of vertebrate paleontology, which had recently been organized by Henry Fairfield Osborn. That year Granger served as field assistant to Jacob L. Wortman on an expedition to collect fossil mammals in the San Juan Basin of New Mexico. In 1897 he worked with the museum's crew collecting dinosaurs in Wyoming. The following summer they retrieved from the rich Bone Cabin quarry enough fossil bones to fill two freight cars, as well as the famed Brontosaurus skeleton found at Nine Mile quarry. Granger's second publication (1901), jointly with Henry Fairfield Osborn, was on sauropod dinosaur limb bones from the Nine Mile deposit. During these years a fruitful friendship and collaboration had begun at the American Museum between Granger, William Diller Matthew, and Albert (Bill) Thomson. In 1903 Osborn assigned to Granger the American Museum's investigations of early mammals in North America. With some important interruptions, this campaign occupied much of the rest of Granger's life. With Thomson as his technical assistant and Matthew as his senior in research he revolutionized knowledge of the Age of Mammals and laid the main basis for early Cenozoic faunal and stratigraphic studies in North America. Among Granger's important expeditions in this connection were those which studied the Eocene of Wyoming (1903-1906, 1909-1914, 1916), the Paleocene and Eocene of New Mexico (1912-1914, 1916), the Eocene of Colorado (1916, 1918), and the Oligocene of South Dakota (1938-1941). Granger's work on other continents became better known than his work in the United States, though it was of no greater importance. In 1907 he went with Osborn to North Africa and made a large collection of early mammals from the Fayum region of Egypt. Most of his time between 1921 and 1931 was spent collecting fossil vertebrates and making stratigraphic studies in China and Mongolia. The fossils which Granger and his assistants, including Bill Thomson, unearthed in Mongolia, in the course of the American Museum's Central Asiatic Expeditions directed by Roy Chapman Andrews, became world famous. Granger served as second in command and chief paleontologist of these expeditions, which explored the Gobi Desert in a caravan of camels and trucks in 1922 and 1923, 1925, 1928, and 1930. The finding of dinosaur eggs (not, in fact, the first known) was most widely acclaimed, but this was of relatively little importance compared with the unexpected and stunning discovery of a long sequence of rich and bizarre faunas of fossil vertebrates, hitherto completely unknown, extending from dinosaurs early in the Age of Reptiles through a whole succession of faunas in the Age of Mammals up to our own time. The collections revealed literally hundreds of animals new to science and included, among many others, a whole growth series of frilled dinosaurs, the earliest known mammal skulls, the largest known land mammal (a rhinoceros, Baluchitherium), and shovel-tusked mastodons. Preliminary descriptions of many of the Asiatic discoveries were published jointly by Granger and Matthew and, after Matthew's death in 1930, by Granger and William K. Gregory, another colleague at the American Museum. Even in the late 1960's, however, the study was not yet complete, and a third generation of paleontologists was still carrying out research on Granger's Asiatic discoveries. A self-made scientist, Granger advanced to the rank of curator (equivalent to the university rank of full professor) in 1927. He published some seventy-five technical research papers, along with numerous notes, reviews, and popular articles. He was impatient of the routine of reports, and the actual words of his papers were sometimes written by a co-author, though with his active collaboration. His "Revision of the Eocene Horses" (1908), a model treatment, remained standard for several decades. His major publication was probably the memoir on the classic American Paleocene mammalian faunas on which he collaborated with Matthew, but he removed his name from the title page when he edited the work after Matthew's death. Granger died in his sleep of a coronary thrombosis in Lusk, Wyoming, while returning with Thomson to a field camp after attending a conference of the Society of Vertebrate Paleontology. His ashes were scattered on his mother's grave in Pleasant View Cemetery in his hometown of Middletown Springs, Vermont.
President of the Explorers Club of New York (1935-1937)
Granger was an extrovert, a jolly companion welcome in any company, who became a great collector, field geologist, and stratigrapher. A highly social person, loved by his associates, he was active in a number of professional societies and clubs.
On April 7, 1904, Granger married a first cousin, Annie (Anna) Dean Granger of Brooklyn. They had no children.
