The sound of little prehistoric feet tells the story of the world’s first nursery.
The imprint of those baby feet, made 190 million years ago, is providing clues to child-rearing practices among dinosaurs.
Scientists believe they have unearthed the oldest known nesting site, and with it a dinosaur nursery in the Golden Gate National Park in the Free State.
The study involved examining clutches of eggs – some still with embryos – and tiny dinosaur footprints.
Those doing the nesting were Massospondylus, a 6 metre-long dinosaur that was so common that scientists often refer to them as the sheep of their time.
It is the spoor, left on slabs of sedimentary rock, that suggests Massospondylus was a caring and doting parent.
“The footprints range in size. Some are so tiny, they had to have been hatchlings. Others are twice that size, but not the size of adults, says Dr Adam Yates, who was at the Bernard Price Institute (BPI) for Palae-ontological Research at Wits University at the time when the study was completed.
“It shows that hatchlings were doubling in size before moving away from the nesting area.”
This behaviour, the scientists believe, suggests that perhaps the parents were feeding their young.
“The babies were toothless, so they were probably being provisioned by their parents, maybe being fed regurgitated food,” says Yates. When they got to a certain size, they left the nest area.
The nests, believes Yates, were close to a water source. That same water source, a river perhaps, flooded the site and preserved it.
The paper, “Oldest known dinosaurian nesting site and reproductive biology of the Early Jurassic sauropodomorph Massospondylus” appears in the latest issue of the Proceedings of the National Academy of Sciences.
At least 10 nests have been discovered in the Golden Gate National Park, and each had up to 34 eggs packed in tight clusters. The distribution of the nests suggest to the scientists that the dinosaurs returned to the site over periods of time, and that they might have assembled in groups, to lay their eggs. They also believe the fragile eggs were laid in carefully constructed nests.
“The eggs, embryos and nests come from the rocks of a nearly vertical road cut only 25 metres long,” Professor Robert Reisz, professor of biology at the University of Toronto at Mississauga, said.
“Even so, we found 10 nests, suggesting that there are a lot more nests in the cliff, still covered by tons of rock. We predict that many more nests will be eroded out in time as natural weathering processes continue.”
The nesting ground, say the authors, is 100 million years older than previous known sites.
“Even though the fossil record of dinosaurs is extensive, we actually have very little fossil information about their reproductive biology, particularly for early dinosaurs,” David Evans, a University of Toronto at Mississauga alumnus and a curator of vertebrate palaeontology at the Royal Ontario Museum, said. - The Star