Sauropods were the largest terrestrial animals ever, yet these long-necked dinosaurs emerged from their eggs at less than 5 pounds and a foot long. In our research with biology and geology professor Kristi Curry Rogers, we studied the smallest baby sauropods ever discovered and investigated the growth rates of these tiny giants.
We worked with two partial skeletons of a sauropod called Rapetosaurus krausei that Professor Curry Rogers and her colleagues discovered in 65-million-year-old sediments in Madagascar. Juvenile bones are relatively rare because they are easily crushed or misidentified, but these were well preserved. As we worked through the literature, we realized that the baby Rapetosaurus in our sample were hatchlings and represented the smallest known baby sauropods.
You can learn a lot about an organism’s life by looking at microscopic details deep within its bones. Paleontologists use bones to interpret growth rates, age, and longevity in extinct animals. When investigating the growth rates in dinosaurs, bones are usually embedded in plastic, sliced into thin wafers, and ground by hand until transparent so that minute details can be observed under a microscope. The exceptional preservation of our baby Rapetosaurus sample, combined with the significance of these tiniest sauropods, prompted us to utilize novel, non-destructive techniques to analyze their bones. We used Micro-Computed Tomography, or micro-CT scanning, available through the University of Minnesota’s Geology and Geophysics Department.
Thanks to the fine details revealed by our scans, we determined that the bones were supplied by a dense network of blood vessels that indicated a rapid growth rate. We obtained data that have allowed us to understand the earliest growth in Rapetosaurus without destructively sampling the tiny bones.
In our collaboration with Professor Curry Rogers we learned how to design and execute a project from data collection to professional conference presentation, and are now preparing a paper for publication. We don’t know of another place where we could have worked with such an important collection of unique dinosaur bones or had such ready access to technology such as Macalester’s bone histology lab and the U of Minnesota’s micro-CT scanner.