Dinosaurs, ancient inhabitants of Earth, continue to fascinate. Their existence millions of years ago sparks curiosity about many aspects of their lives, including what their young were called and how they began life.
Unveiling the Term for Young Dinosaurs
For newly hatched dinosaurs, the most widely accepted term is “hatchling.” This term refers to any dinosaur that has recently emerged from its egg. As these young dinosaurs grew but had not yet reached full maturity, they are referred to as “juveniles.” These terms are broadly applied across different dinosaur groups.
Unlike mammals or birds, dinosaurs do not have a single, unique “cute” term like “cub” or “kitten” for their young. While “hatchling” is common, some informal terms occasionally appear. For example, the young of large, long-necked sauropods might sometimes be called “sauropodlets.” Similarly, “chicks” can be used for the young of theropods.
Clues from Fossilized Young
Paleontologists uncover details about young dinosaurs through fossil finds. Fossilized eggs, embryos, and nesting sites provide direct evidence of their early life stages. Early discoveries of dinosaur eggs, like those in Mongolia, confirmed that all dinosaurs reproduced by laying eggs, similar to modern reptiles and birds.
Recent discoveries, such as the exceptionally preserved oviraptorosaur embryo nicknamed “Baby Yingliang,” offer insights. This embryo, estimated to be between 66 and 72 million years old, was found curled in a posture similar to modern bird embryos preparing to hatch, suggesting this behavior originated in their dinosaur ancestors. Fossilized nesting grounds, like those of Maiasaura (“good mother lizard”) in Montana, or the 190-million-year-old Massospondylus site in South Africa, reveal that some species nested in colonies. Some findings, such as 92 nests and 256 eggs of titanosaurs in India, suggest that these large sauropods might have laid eggs and then left their offspring to independently develop, possibly due to their immense size.
The Journey from Hatchling to Adult
The growth and development of dinosaurs from their juvenile stages into full adulthood are studied through analyses of their bones. Paleontologists examine microscopic structures within fossilized bones, looking for “growth rings” similar to those found in tree trunks. These rings reveal yearly periods of growth and can indicate how quickly an individual dinosaur matured. Research shows that growth rates varied considerably among different dinosaur species; some large theropods, like Tyrannosaurus rex, experienced rapid growth spurts during adolescence, while others grew more slowly over a longer period.
Young dinosaurs often exhibited different body proportions and features compared to their adult counterparts. For instance, juveniles might have had larger heads relative to their bodies or lacked the crests and horns that developed later in life. In some cases, such as the theropod Limusaurus inextricabilis, juveniles had teeth that were lost as they matured into toothless adults, indicating a dietary shift. Evidence of parental care, particularly in species like Maiasaura, suggests that adult dinosaurs may have provided food and protection to their young in nests. The discovery of juvenile skeletons, like the recently found “Teen Rex” (a young Tyrannosaurus rex), provides understanding of how these animals changed throughout their lives.