A new study conducted at the University of Calgary looked into the porosity of dinosaur eggs and found that the nesting habits of some dinosaurs may have foreshadowed the nesting habits of birds. They laid their eggs in nest and kept them uncovered like the modern birds today use to have.
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Tanaka and his team, under the supervision of dinosaur egg and nesting site expert Darla Zelenitsky, studied the fossilised eggshell porosity of 30 different dinosaur species before comparing them with the porosity of eggs belonging to 120 species of birds and crocodiles. Researchers have used what little information is available to determine how some species built nests and cared after their eggs prior to hatching.
With a large amount of data gathered though Tanaka’s diligent work on the eggs of living and fossils animals, we plan to dig even deeper on new questions such as how long it took for dinosaurs to hatch their eggs.
According to Sciencemag, Luis Chiappe, a vertebrate paleontologist at the Natural History Museum of Los Angeles County in California said that the findings are in line up other studies that suggest that some birdlike dinosaurs were warm-blooded, which would have enabled them to incubate eggs in an open nest. “Our research revealed that their eggs were exposed, similar to modern birds”, said Tanaka.
“Nest structures are usually not preserved in the fossil record, making it hard to determine if dinosaurs buried their eggs during incubation like crocodiles, or if they were incubated in more open nests as in brooding birds”. The researchers are unsure whether the small theropods brooded on their nests but some fossil evidence suggests that some small dinosaurs did do this, Zelenitsky said.
This discovery is quite important, as it shows the way dinosaurs evolved into their modern day counterparts, be them birds or reptiles, through the evolution of their nests. “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”.
“Fossil eggs are more challenging to study because fossil specimens are often incomplete”, said Tanaka.
Luckily, researchers can compare the fossilized eggs of dinosaurs to those of the dinosaur’s closest living relatives: crocodiles and birds. They found that most dinosaurs, such as sauropods, laid their eggs similar to the crocodiles. Plus, in buried nests airflow is somewhat limited, thus requiring eggs to be relatively porous to help increase the flow of oxygen into and carbon dioxide out of the eggs. A switch from buried nests to open nesting and brooding would ensure that the eggs of advanced theropods (including birds) would be safe from ground predators, which may have played a large role in their evolutionary success.
The team of researchers managed to explain how different nesting techniques would impact the eggshell’s morphology. Moreover, the vegetation or the dirt covering the eggs provided an optimal temperature for the newborn. “We can see some change through the evolution of dinosaurs”.
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It is anticipated that this research will pave the way for further inquiries into the world of dinosaurs’ nesting habits.
