Newly Discovered Baby Titanosaur Sheds Light on Dinosaurs' Early Lives

“This baby’s limbs at birth were built for its later adult mass; as an infant, however, it weighed just a fraction of its future size,” Curry Rogers said. “This is our first opportunity to explore the life of a sauropod just after hatching, at the earliest stage of its life.”

Along with researchers Megan Whitney of the University of Washington, Mike D’Emic of Adelphi University, and Brian Bagley of the University of Minnesota, the team studied thin-sections of the tibia and used a high-powered CT scanner to get a closer look at the microstructures preserved inside the limb bones.

Microscopic bone features

The detailed microscopic features of the Rapetosaurus bones revealed patterns similar to those of living animals and made it possible for the scientists to reconstruct the beginning of the dinosaur’s post-hatching life.

“We looked at the preserved patterns of blood supply, growth cartilages at the ends of limb bones, and at bone remodeling,” Curry Rogers said. “These features indicate thatRapetosaurus grew as rapidly as a newborn mammal and was only a few weeks old when it died.”

The tiny titanosaur was mobile at hatching and less reliant on parental care than other animals. Baby sauropods like Rapetosaurus were somewhat like miniature adults, Curry Rogers said.

The team also observed microscopic zones deep within the bones. They proved similar to the hatching lines in today’s reptiles, and to neonatal growth lines in extant mammals.

The zones indicate the time of hatching in Rapetosaurus, and allowed the scientists to estimate the weight of the newly hatched Rapetosaurus — around 7.7 pounds.

Demise in a drought

What caused the demise of this baby Rapetosaurus?

Clues came from its cartilage growth plates, which bear a striking resemblance to the modified growth cartilages that occur during starvation among living vertebrates.

When taken in the context of the intensely drought-stressed ecosystem represented in the Maevarano Formation, it’s clear that this Rapetosaurus had it rough, Curry Rogers said.

“Between its hatching and death just a few weeks later,” she said, “this baby Rapetosaurusfended for itself in a harsh and unforgiving environment.”

Citation: Precocity in a tiny titanosaur from the Cretaceous of Madagascar Kristina Curry Rogers, Megan Whitney, Michael D’Emic, Brian Bagley Science 22 Apr 2016:Vol. 352, Issue 6284, pp. 450-453 DOI: 10.1126/science.aaf150 http://dx.doi.org/10.1126/science.aaf1509