Pictures: Oldest Dinosaur Nests Found in South Africa

Dino Day Care

Illustration courtesy Julius Csotonyi

A Massospondylus parent cares for its young in an artist's rendering.

The newfound dinosaur-egg clutches provide the oldest evidence yet for several aspects of dinosaur behavior, according to the study.

For example, paleontologists found multiple nests in a single layer of rock, suggesting that mothers gathered in groups to lay their eggs. This is the oldest example of "colonial nesting" in the fossil record, the scientists say.

(See "Pictures: 'Gorgeous' Dinosaur Nest Found Full of Babies.")

Published January 24, 2012

Baby Print

Photograph courtesy D. Scott

The tiny footprint of a baby Massospondylus was also found at the South African nesting site.

The print suggests that the young dinosaurs "stayed around the nest after they hatched, at least until they grew about twice their size," study co-author Reisz said.

Staying put means that the newborn babies must have relied on their parents for food and protection—the "actual, real first evidence of it in the fossil" record, he said.

(See "Rare Fossil Embryos Reveal Dinosaur Growth.")

Published January 24, 2012

Ancient Egg Clutch

Photograph courtesy D. Scott

One of the newfound egg clutches contained 34 eggs (pictured), which were likely submerged during a flood. The shells' extreme thinness—only about a hundred microns wide—made them hard to spot, Reisz noted.

Eggs in the clutches were arranged in single layers, meaning a mother dino must have created a "controlled nesting environment" by possibly organizing the eggs, he added.

The scientists were also surprised to find several generations of nests in different levels of rocks, suggesting the dinosaurs regularly returned to the same site to lay their eggs.

(See "Dinosaur Dads Played "Mr. Mom"?)

Published January 24, 2012

Original Clutch

Photograph courtesy D. Scott

An egg clutch recovered from the South African site in 1976 (pictured) had two exposed skeletons, including the embryo in the first picture of this gallery, which wasn't formally studied until 2005. These embryos have since given scientists valuable insights into dinosaur evolution.

For example, the Massospondylus embryo resembles "a dwarf version of a sauropod dinosaur," the largest animals to walk the Earth, Hans-Dieter Sues, a paleontologist at the National Museum of Natural History in Washington, D.C., said in 2010. (See a sauropod picture.)

This means that Massospondylus had characteristics that "foreshadowed" the look of sauropods, which evolved later, he said.

Published January 24, 2012