Dinosaurs had adopted an innovative nesting technique in the Jurassic era that still helps modern day birds and crocodiles, discovered researchers.
The highly fragile remains of eggshells, dating back 150 million years, is helping researchers uncover one of the most perplexing mysteries about dinosaurs. A new study published by University of Calgary researchers, is trying to settle a debate that’s been going on for ages between paleontologists: How did the dinosaurs incubate their eggs. Speaking about the same, study co–author Kohei Tanaka of the University of Calgary said:
“Nest structures are usually not preserved in the fossil record, making it difficult to determine if dinosaurs buried their eggs during incubation like crocodiles, or if they were incubated in more open nests as in brooding birds. There are many papers that seek the incubation method of dinosaurs, but our research is one of the most comprehensive studies in that it analyzes large datasets on the eggs of both living and fossil species.”
The study, published in the journal Plos One, has for the first time, revealed a definitive link between dinosaur eggshell porosity and different nesting types, reported Fox News. The study proves there’s a strong connection between the nesting styles of the dinosaurs and that of modern day birds and crocodiles. Science has long proved that, though the two species might be completely independent from each other today, millions of years ago, they developed from dinosaurs.
To find out exactly how the dinosaur nesting took place, the team studied 30 types of dinosaur eggs. More specifically, Tanaka and his team, which involved dinosaur egg and nesting site expert Darla Zelenitsky, closely examined eggshell porosity of the fossilized remains. Thereafter, they cross-referenced the porosity of eggs belonging to 120 species of birds and crocodiles. Explaining the technique and challenges involved, Tanaka continued:
“Fossil eggs are more challenging to study because fossil specimens are often incomplete. However, some of the microscopic features of the eggshell, such as porosity, are preserved, and can be used to infer the types of nests in dinosaurs in the absence complete nests.”
So how did dinosaur nesting take place? The study concluded that majority of the dinosaurs had adopted an innovative technique of preserving and incubating their eggs. They buried their eggs in nests covered with dirt and vegetation, reported The Christian Science Monitor. This technique is commonly observed in modern day crocodiles. Modern day crocodiles carefully dig holes in the loose soil near riverbeds. The nesting spot is usually hidden by dense vegetation. After the mother lays eggs, she covers the eggs with soil, dirt and vegetation, which kept the eggs warm. Once the eggs hatch, the babies crawl out of the dirt.
Interestingly, not all dinosaurs adopted this nesting technique, shared researchers. Quite a few theropods – or bipedal, meat-eating dinosaurs – laid their eggs in open nests. Needless to say, this type of dinosaur later evolved into modern-day birds, said study co-researcher Darla Zelenitsky, an assistant professor of paleontology at the University of Calgary in Canad,
“The evolution of open nests and brooding behavior could have allowed small theropod dinosaurs, and obviously birds, to move to other nesting locations other than on the ground. This may have helped their evolutionary success.”
The researchers were able to settle the argument by looking at the porosity of the eggshells, reported HNGN. Previous research has indicated eggs that are incubated in open nests have a very low porosity, while those eggs that are buried have a high porosity. This strongly indicates dinosaurs, such as long–necked sauropods and carnivorous theropods, which laid high porosity eggs, had adopted a buried-nest nesting technique, while advanced theropods, including the bird–like maniraptorans, laid low porosity eggs, suggesting they laid their eggs in open nests. What’s peculiar is that the researchers also found evidence that suggests theropods may have partially buried or at least covered their eggs, presumably to protect from other predators.
Researchers caution that the nesting styles may have gradually changed and the discovery of more fossilized eggshells could offer a definitive answer.
[Photo by Rob Stothard / Getty Images]