Roy Chapman Andrews traveled the world studying fossils, from mammals to dinosaurs, during the first half of the twentieth century. Andrews worked and collected fossil specimens for the American Museum of Natural History (AMNH) in New York City, New York. Throughout his career, Andrews collected bones of many animal species, including a previously unknown species of a horned, herbivorous dinosaur, later named Proceratops andrewsi in his honor. Andrews published widely read narratives about his travels and field experiences, such as On the Trail of Ancient Man and Across Mongolian Plains. Andrews led expeditions for the Central Asiatic Expeditions in the Gobi Desert, which recovered many previously unknown fossil specimens. His Central Asiatic team discovered the first scientifically recognized dinosaur eggs, which provided scientists with information about the eggs that dinosaurs produced.

Oviraptor philoceratops was a small bird-like dinosaur that lived about seventy-five million years ago, during the late Cretaceous period. In 1923, George Olsen of the American Museum of Natural History (AMNH) in New York City, New York, discovered the first Oviraptor fossilized skeleton on top of a dinosaur egg nest in the Gobi Desert, Mongolia. Because of the close proximity of dinosaur and nest, when Henry Fairfield Osborn president of the AMNH published on the discovery, he assumed that the Oviraptor had died attempting to steal the eggs. However, since the initial discovery, more Oviraptor adults, eggs, and a well-preserved embryo fossil have confirmed that Oviraptors were parents who sat on their nests, a behavior called brooding common among birds. The fossils of Oviraptor philoceratops, from eggs and embryos to adults, provide evidence about dinosaur growth, development, and reproductive behaviors.

In nineteenth century Great Britain, Thomas Henry Huxley proposed connections between the development of organisms and their evolutionary histories, critiqued previously held concepts of homology, and promoted Charles Darwin's theory of evolution. Many called him Darwin's Bulldog. Huxley helped professionalize and redefine British science. He wrote about philosophy, religion, and social issues, and researched and theorized in many biological fields. Huxley made several methodological contributions to both invertebrate and vertebrate embryology and development, and he helped shape the extra-scientific discourse for these fields.

Stephen Jay Gould studied snail fossils and worked at Harvard University in Cambridge, Massachusetts during the latter half of the twentieth century. He contributed to philosophical, historical, and scientific ideas in paleontology, evolutionary theory, and developmental biology. Gould, with Niles Eldredge, proposed the theory of punctuated equilibrium, a view of evolution by which species undergo long periods of stasis followed by rapid changes over relatively short periods instead of continually accumulating slow changes over millions of years. In his 1977 book, Ontogeny and Phylogeny, Gould reconstructed a history of developmental biology and stressed the importance of development to evolutionary biology. In a 1979 paper coauthored with Richard Lewontin, Gould and Lewonitn criticized many evolutionary bioligists for relying solely on adaptive evolution as an explanation for morphological change, and for failing to consider other explanations, such as developmental constraints.

To study human evolution, researchers sometimes use microstructures found in human teeth and their knowledge of the processes by which those structures grow. Human fetusus begin to develop teeth in utero. As teeth grow, they form a hard outer substance, called enamel, through a process called amelogenesis. During amelogenesis, incremental layers of enamel form in a Circadian rhythm. This rhythmic deposition leaves the enamel with microstructures, called cross-striations and striae of Retzius, which have a regular periodicity. Because enamel is not renewed throughout life like other tissues, teeth preserve the timing and details of a person's growth and development. Thus, enamel microstructures, from living people and from fossilized teeth, can be used to reconstruct the growth, development, and life histories of current and past humans. Researchers can also compare current and fossilized microstructures to trace changes in those traits over the course of human evolution.

When scientists discovered a 3.3
million-year-old skeleton of a child of the human lineage (hominin) in
2000, in the village of Hadar, Ethiopia, they were able to study growth
and development of Australopithecus
afarensis, an extinct hominin species. The team of researchers,
led by Zeresenay Alemseged of the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, named the fossil DIK 1-1 and nicknamed
it Dikika baby after the Dikika research site. The Dikika fossil
preserves much of the skull, including the jaw and teeth, which enabled
scientists to study the teeth microstructures and to reconstruct the
pace at which individuals of the hominin A. afarensis
developed.

Dinosaur egg parataxonomy is a classification system that organizes dinosaur eggs by descriptive features such as shape, size, and shell thickness. Though egg parataxonomy originated in the nineteenth century, Zi-Kui Zhao from Beijing, China, developed a modern parataxonomic system in the late twentieth century. Zhao's system, published in 1975, enabled scientists to organize egg specimens according to observable features, and to communicate their findings. The eggshell protects the developing embryo, enables gas exchange between the embryo and the environment external to the egg, and the internal components of the egg provide nutrients for the embryo. Those external and internal features that support a developing embryo leave their mark on eggshells. Dinosaur egg parataxonomy classifies those characteristics and provides insight into dinosaur egg-laying behaviors, reproductive physiology, and embryonic development.

In 1978, James Kitching discovered two dinosaur embryos in a road-cut talus at Roodraai (Red Bend) in Golden Gate Highlands National Park, South Africa. Kitching assigned the fossilized embryos to the species of long necked herbivores Massospondylus carinatus (longer vertebra) from the Early Jurassic period, between 200 and 183 million years ago. The embryos were partially visible but surrounded by eggshell and rock, called matrix. Kitching said that the eggs were too delicate to remove from the matrix without damage. Twenty-seven years later in 2005, Diane Scott, a member of a team led by Robert Reisz from the University of Toronto in Toronto, Canada, uncovered the two almost complete, well-articulated embryos. Scientists have inferred information from the embryos about Massospondylus dinosaurs' growth, development, and behaviors including parental care, gait, and locomotion.