IIlustrated by Julius Csotonyi
Nov. 26, 2015
Researchers look at fossilized eggs to explain evolution of dinosaur nests
Dinosaurs have long captured mankind鈥檚 imagination, primarily because of the many questions emerging from their very distant existence.
Recent research from the 草莓污视频导航 is helping to close that knowledge gap by linking the porosity of fossilized eggs with dinosaurs鈥 nesting styles, potentially explaining the evolutionary success of current brooding birds.
Kohei Tanaka, a PhD student in the聽, recently published a paper in聽聽where he and his co-authors demonstrate, for the first time, the link between dinosaur eggshell porosity and different nesting types. The article establishes how dinosaur egg nesting styles correlate with current crocodile covered nests as well as modern, exposed open-bird nests.
鈥淒inosaur nest structures and nesting materials are usually not preserved in the fossil record,鈥 says Tanaka. 鈥淚n the past, this lack of data has made working with dinosaur eggs and eggshells extremely difficult to determine how dinosaurs built their nests and how the eggs were incubated for hatching young.鈥
Study compared egg porosity of dinosaurs to birds and crocodiles
Working under the supervision of聽Darla Zelenitsky, assistant professor and聽a world expert in dinosaur eggs and nesting sites in the聽, Tanaka conducted an in-depth study of the egg porosity of 30 different dinosaur species. He compared those results with the egg porosity of 120 species of birds and crocodiles, which are the closest living relatives to dinosaurs.
鈥淏rooding birds, which incubate their eggs in open nests, tend to have low eggshell porosities compared to crocodiles and megapode bird species that incubate in buried nests,鈥 explains Tanaka.
The study鈥檚 results show that most dinosaurs, including the long-necked sauropods, primitive meat-eating theropods and possibly plant-eating ornithischians, produced low porosity eggshells and therefore, were highly likely to bury their eggs in nests much like their crocodile predecessors.
Riley Brandt, 草莓污视频导航
Shift in nest type and incubation style during evolution towards birds
Advanced theropods like the maniraptorans featured high porosity eggshells, suggesting that they laid and incubated their eggs in open nests in a similar fashion as their most closely related living birds. Other paleontological evidence also revealed that these early open-nesters did, however, still partly bury their eggs.
The researchers concluded that it was probably not until modern-looking birds that open nests with fully exposed eggs came to be, meaning that there was a shift in the type of nest, and probably incubation style of dinosaurs, during their evolution toward birds.
鈥淏ecause buried nests needed to be built and incubated on the ground, open nesting and brooding may have allowed advanced theropods 鈥攊ncluding birds 鈥斅爐o incubate eggs in a greater diversity of locations and occasionally away from ground predators, potentially contributing to their evolutionary success,鈥 says Zelenitsky, referring to birds as the most diverse living species with more than 10,000 unique types.
Laying the groundwork for further research into dinosaur nesting habits
It is anticipated that this research will pave the way for further inquiries into the world of dinosaurs鈥 nesting habits.
鈥淲ith a large amount of data gathered though Tanaka鈥檚 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,鈥 says Zelenitsky.
This work, done in collaboration with Fran莽ois Therrien from the聽, was made possible thanks to a scholarship to Tanaka from the Yoshida Scholarship Foundation, the Japan Student Services Organization, a Natural Science and Engineering Research Council of Canada (NSERC) Discovery Grant to Zelenitsky, as well as funding from the 草莓污视频导航 and the Royal Tyrrell Museum.
Darla Zelenitsky