Twin discoveries reveal that some ancient reptiles laid soft-shelled eggs, challenging long-held assumptions in paleontology

The new evidence that some dinosaurs and their extinct reptilian contemporaries laid eggs without hard shells helps explain the rarity of eggs in the first half of the fossil record, according to the Times. Soft shells tend to rot away quickly, which would have made it less likely for them to fossilize. Both finds may have implications for the reproductive evolution of dinosaurs and ancient reptiles.

“Over the last 20 years, we’ve found dinosaur eggs around the world. But for the most part, they only represent three groups—theropod dinosaurs, which includes modern birds, advanced hadrosaurs like the duck-bill dinosaurs, and advanced sauropods, the long-necked dinosaurs,” says Mark Norell, paleontologist at the American Museum of Natural History and lead author of the study, in the statement from the museum. “At the same time, we’ve found thousands of skeletal remains of ceratopsian dinosaurs, but almost none of their eggs. So why weren’t their eggs preserved? My guess—and what we ended up proving through this study—is that they were soft-shelled.”

The recognition that the fossils contained the remnants of soft-shelled eggs came from chemical analysis prompted by strange haloes surrounding the embryos, according to the Times. Molecular paleobiologist Jasmina Wiemann of Yale University compared the chemical composition of these haloes surrounding the fossil embryos to that of modern hard and soft-shelled eggs and found the chemical fingerprint of the fossils matched the eggs with soft shells, she tells the Times.

“The dinosaur calcified egg is something that is not ancestral, that is not sort of a primitive feature of all dinosaurs,” Wiemann tells NPR.

The soft-shell revelation also suggests that many dinosaurs buried their eggs like some modern reptiles, since soft shells lose moisture quickly and couldn’t withstand the weight of a brooding parent.

“The idea that the ancestral dinosaur laid soft-shelled eggs like a turtle is a bold hypothesis, but I like it,” Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the study, tells the Times. “It’s a stunning revelation—and it’s remarkable to think of these giant dinosaurs, larger than buses and in some cases airplanes, starting out as little pipsqueaks tearing their way out of a soft egg.”

https://www.smithsonianmag.com/smart-news/first-soft-shelled-dinosaur-eggs-found-180975137/

PermeateFree said:

Twin discoveries reveal that some ancient reptiles laid soft-shelled eggs, challenging long-held assumptions in paleontology

The new evidence that some dinosaurs and their extinct reptilian contemporaries laid eggs without hard shells helps explain the rarity of eggs in the first half of the fossil record, according to the Times. Soft shells tend to rot away quickly, which would have made it less likely for them to fossilize. Both finds may have implications for the reproductive evolution of dinosaurs and ancient reptiles.

“Over the last 20 years, we’ve found dinosaur eggs around the world. But for the most part, they only represent three groups—theropod dinosaurs, which includes modern birds, advanced hadrosaurs like the duck-bill dinosaurs, and advanced sauropods, the long-necked dinosaurs,” says Mark Norell, paleontologist at the American Museum of Natural History and lead author of the study, in the statement from the museum. “At the same time, we’ve found thousands of skeletal remains of ceratopsian dinosaurs, but almost none of their eggs. So why weren’t their eggs preserved? My guess—and what we ended up proving through this study—is that they were soft-shelled.”

The recognition that the fossils contained the remnants of soft-shelled eggs came from chemical analysis prompted by strange haloes surrounding the embryos, according to the Times. Molecular paleobiologist Jasmina Wiemann of Yale University compared the chemical composition of these haloes surrounding the fossil embryos to that of modern hard and soft-shelled eggs and found the chemical fingerprint of the fossils matched the eggs with soft shells, she tells the Times.

“The dinosaur calcified egg is something that is not ancestral, that is not sort of a primitive feature of all dinosaurs,” Wiemann tells NPR.

The soft-shell revelation also suggests that many dinosaurs buried their eggs like some modern reptiles, since soft shells lose moisture quickly and couldn’t withstand the weight of a brooding parent.

“The idea that the ancestral dinosaur laid soft-shelled eggs like a turtle is a bold hypothesis, but I like it,” Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the study, tells the Times. “It’s a stunning revelation—and it’s remarkable to think of these giant dinosaurs, larger than buses and in some cases airplanes, starting out as little pipsqueaks tearing their way out of a soft egg.”

https://www.smithsonianmag.com/smart-news/first-soft-shelled-dinosaur-eggs-found-180975137/

Soft as in leather type look

I posted this back on the 19th. In thread “https://tokyo3.org/forums/holiday/topics/13802/”

mollwollfumble said:

Also have a look at https://www.nytimes.com/2020/06/17/science/dinosaurs-soft-eggs.html

“There’s a problem with dinosaur eggs: A lot of them are missing. … A new study published Wednesday in Nature, showcasing baby dinosaur remains from Mongolia and Argentina, offers a reason: The very first dinosaurs laid soft eggs like turtles do today, and their eggs decomposed long before they could ever turn into fossils. In a second study also published in Nature, paleontologists announced the first known fossil egg found in Antarctica. The egg, also soft-shelled, looks like a deflated football. It’s bigger than any dinosaur egg ever found, and the team that unearthed it thinks it might be the egg of a mosasaur. Both studies scramble scientific understanding of ancient reptile reproduction.”

I don’t like calling them “reptiles”. Even mosasaurs are closer to birds than to squamates. But if both dinosaurs and squamates laid soft-shelled eggs then perhaps the relationship is closer than I thought.

“Dr. Norell was in Mongolia excavating dinosaur fossils in the Gobi Desert. There, he unearthed the fossil babies of a dinosaur called Protoceratops. The Protoceratops babies died sometime between 75 and 71 million years ago, and they’re curled in fetal positions. They look as if they should still be sheltering in their eggs. But there were no fossilized eggshell fragments. Instead, a thin film surrounded the animals. Paleontologists regularly unearth large hauls of dinosaur eggs at excavation sites. But these eggs were always younger than the middle of the Jurassic Period.”

“Ms. Wiemann analyzed the chemistry of hard and soft eggs from animals like chickens and turtles, and she found that each shell type produces a unique chemical fingerprint. She then looked at the chemistry of the Protoceratops films, as well as films from the egg of another dinosaur from Argentina called Mussaurus, and found that the dinosaur eggs matched the soft shell fingerprint. That was incredibly exciting. They realized that the common ancestor of all the dinosaurs must have laid soft eggs.”

mollwollfumble said:

I posted this back on the 19th. In thread “https://tokyo3.org/forums/holiday/topics/13802/”

mollwollfumble said:

Also have a look at https://www.nytimes.com/2020/06/17/science/dinosaurs-soft-eggs.html

“There’s a problem with dinosaur eggs: A lot of them are missing. … A new study published Wednesday in Nature, showcasing baby dinosaur remains from Mongolia and Argentina, offers a reason: The very first dinosaurs laid soft eggs like turtles do today, and their eggs decomposed long before they could ever turn into fossils. In a second study also published in Nature, paleontologists announced the first known fossil egg found in Antarctica. The egg, also soft-shelled, looks like a deflated football. It’s bigger than any dinosaur egg ever found, and the team that unearthed it thinks it might be the egg of a mosasaur. Both studies scramble scientific understanding of ancient reptile reproduction.”

I don’t like calling them “reptiles”. Even mosasaurs are closer to birds than to squamates. But if both dinosaurs and squamates laid soft-shelled eggs then perhaps the relationship is closer than I thought.

“Dr. Norell was in Mongolia excavating dinosaur fossils in the Gobi Desert. There, he unearthed the fossil babies of a dinosaur called Protoceratops. The Protoceratops babies died sometime between 75 and 71 million years ago, and they’re curled in fetal positions. They look as if they should still be sheltering in their eggs. But there were no fossilized eggshell fragments. Instead, a thin film surrounded the animals. Paleontologists regularly unearth large hauls of dinosaur eggs at excavation sites. But these eggs were always younger than the middle of the Jurassic Period.”

“Ms. Wiemann analyzed the chemistry of hard and soft eggs from animals like chickens and turtles, and she found that each shell type produces a unique chemical fingerprint. She then looked at the chemistry of the Protoceratops films, as well as films from the egg of another dinosaur from Argentina called Mussaurus, and found that the dinosaur eggs matched the soft shell fingerprint. That was incredibly exciting. They realized that the common ancestor of all the dinosaurs must have laid soft eggs.”

Sorry, it did not register with me.