Dinosaur Eggs and Babies
What were the smallest and biggest eggs ever found? Scientists answer students' questions.
- Grades: 3–5, 6–8, 9–12
The following questions were answered by dinosaur expert Don Lessem and paleontologist Bill Hammer.
Q: How do dinosaurs make their eggs?
A: Dinosaurs made eggs the same way reptiles and birds do today. Females produced them inside their body. Some dinosaurs laid as many as 21 eggs in a single nest. (Don Lessem)
Q: How do dinosaurs lay eggs?
A: Dinosaurs laid eggs in clusters, sometimes in a spiral in a nest they dug out and covered over with vegetation to keep it warm. They laid eggs that were oval, round or football-shaped and as small as tennis balls and as long as 18 inches. (Don Lessem)
Q: What do dinosaur eggs look like?
A: Dinosaur eggs come in many shapes and sizes from cannonballs to giant footballs. The biggest are 18 inches long and the smallest are the size of tennis balls. They are laid in nests that were probably covered with plants to keep warm — you wouldn't want a dinosaur sitting on them! We've found as many as 21 eggs in one nest. (Don Lessem)
Q: What were the smallest and biggest eggs ever found?
A: The biggest dinosaur eggs we know are shaped like giant footballs and are about 19 inches long. They belong to a meat-eater from Asia called segnosaurus. The smallest dinosaur eggs are just a few inches across and more tennis ball-shaped and we don't know what dinosaur made them. (Don Lessem)
Q: How did dinosaur eggs hatch?
A: Dinosaurs hatched very carefully. I don't think their parents sat on the eggs or you'd have scrambled dinosaurs. Maybe the parents mounded warm plants on top of the eggs to keep the babies warm until they hatched. And maybe, like birds, little dinosaurs pecked their way out of the shell with an egg tooth on their beaks. We don't have any proof that they had such a tooth though. (Don Lessem)
Q: Were there any dinosaur twins or triplets?
A: Some dinosaurs had more than 20 eggs in their nest. It is certainly possible to have twins among egg-laying animals. Have you ever had a double-yolk egg when you made an omelet? Those would be twins if they were fertile hatched eggs. Same might be true for dinosaurs. (Don Lessem)
Q: How rapidly do dinosaurs grow after hatching?
A: The babies grew fast after hatching. In six weeks they might double in size, at least the duckbill babies we know best seem to have. (Don Lessem)
Q: How many eggs would a velociraptor have in one lifetime?
A: It is difficult to estimate how many eggs a dinosaur, such as velociraptor, might have laid in a lifetime. If they were like birds, and laid eggs only once a year with a nest size of 10 to 15 eggs, you can make a guess, but to do so you have to estimate how many years an adult dinosaur could reproduce, and that is hard to do. (Bill Hammer)
Q: Have any eggs been found from T-rex?
A: No, not so far. (Don Lessem)
Q: How did dinosaurs protect their nests from predators?
A: We don't have much evidence of how parent dinosaurs protected their babies in the nest but we just got some possible explanation. Last year, scientists found a nest of oviraptor eggs and the parent on top of the nest. They also found two tiny velociraptor skulls nearby. Maybe the baby velociraptors were trying to sneak into the nest and eat the oviraptor babies and the mother or father oviraptor killed them. (Don Lessem)
Q: Is the maiasaura considered the good mother of the dinosaurs? If so, why?
A: Maiasaura means good mother. Dr. Jack Horner named it because he saw evidence that it took good care of its babies, feeding them chewed up plants (yecch) while they were too weak as newly-hatched babies to leave the nest. Other dinosaurs were probably good parents, too. Oviraptor dinosaurs from Mongolia have been found on top of their eggs. Other dinosaurs, like the orodomeus, the little planteater from Montana in maiasaura's time, were born up-and-running. They didn't need parents to take care of them so those babies probably didn't have good mothers. (Don Lessem)
Q: How big was a baby brontasaurus?
A: It all depends how young it was. We don't know any baby brontosaurs, or apatosaurus as scientists call them, but they probably came from eggs no bigger than a cannonball. All curled up they were probably less than a few feet long at birth, but grew very fast since they got to be over 80 feet long! (Don Lessem)