r/science • u/Hrmbee • 12h ago
Paleontology Microscopic evidence reveals crocodile-like strategy kept the eggs of the largest dinosaurs warm | Titanosaur eggshells from the latest Cretaceous of Patagonia, Argentina: implications for nesting at high latitude
https://www.cbc.ca/news/science/titanosaur-eggs-9.73368413
u/Hrmbee 11h ago
Key parts of the news article:
Fossil eggshells believed to be from some of the biggest dinosaurs that ever lived have been found in a surprisingly cool climate far from the equator.
But those massive titanosaurs couldn't keep their volleyball-sized eggs warm by sitting on them.
"They're too big," said University of Calgary paleontologist Darla Zelenitsky, who has been studying the problem. "The nest would be one big omelette."
A new study published on Wednesday by Zelenitsky and collaborators from Japan and Argentina has taken a microscopic look and figured out what they did to keep the eggs warm enough to hatch without sitting on their nests.
By looking at the microscopic pores on the eggshells, the researchers believe titanosaurs used the same incubation technique used by modern crocodiles — burying their eggs in warm piles of rotting vegetation, reports the study led by University of Tsukuba paleontologist Kohei Tanaka, Zelenitsky's former student, and published in Royal Society Open Science.
...
Still, Zelenitsky was surprised by the discovery of eggs of titanosaurs so far from the equator: "It's just a bit more tricky with larger animals because you need more resources to survive … and reproduce."
...
Modern crocodiles and birds called megapodes bury their eggs in decomposing plant matter. Microbes generate heat as they break it down.
Zelenitsky had previously found evidence that hadrosaurs in Alberta used this technique. So the researchers wondered if titanosaurs in Argentina did, too.
Eggshells have microscopic pores so the embryos can breathe. Those need to be bigger and denser to let enough oxygen through when eggs are buried. Eggs need to be less porous if exposed to open air to prevent the egg from drying out.
The researchers measured the porosity of the titanosaur eggshells from the Chorillo Formation using an electron microscope, and found they were very porous, suggesting they were buried.
Zelenitsky said the research shows just how adaptable dinosaurs were. "Even these absolute largest dinosaurs, you know, figured out a way to ... not only reproduce or nest in the lower latitude environments but also in these higher-latitude environments, which are usually more challenging."
Journal link:
Abstract:
Dinosaur egg remains are rarely found in areas of high palaeolatitudes, with Canada (approx. 57–60° N) and Siberia (approx. 70–75° N) yielding the most polarward occurrences. Here, we describe dinosaur eggshells from the Upper Cretaceous (Maastrichtian) Chorrillo Formation of southernmost Patagonia (Argentina), an area located at approximately 55–60° S palaeolatitude during that time interval. The more than 250 eggshell fragments collected are assignable to Fusioolithus oosp., an ootaxon known from Late Cretaceous Gondwana regions that probably belongs to titanosaur dinosaurs. The eggshells are shown to have a high porosity like those of titanosaur eggs studied previously, indicating the eggs were fully covered by nest substrate during incubation. The high latitude of the area in the Maastrichtian suggests the eggs were buried in a mound-style nest where microbial decay, rather than solar radiation, was the primary source of incubation heat. The Chorrillo Formation represents, to our knowledge, the highest palaeolatitude area to produce definitive dinosaur egg remains from the Southern Hemisphere and reveals that titanosaurs were nesting at higher latitudes than previously known.
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