Seventy-five million years ago in southern Alberta, a river flooded, burying the eggs of bird-like dinosaurs nesting on the nearby plain. Now, tiny pieces of those fossil egg shells offer new evidence about how dinosaurs lived, bred and evolved into birds.
A new study shows emu-sized, meat-eating troodons were as warm-blooded as birds, with body temperatures of more than 40 C. But unlike modern birds such as chickens that can produce one egg a day, troodons used a very slow egg-forming process similar to the one used by reptiles like crocodiles.
That supports a previous hypothesis that nests found containing up to two dozen eggs were shared by multiple troodons, similar to the way ostriches share communal nests today.
François Therrien, curator of dinosaur paleobiology at the Royal Tyrell Museum in Alberta and co-author of the study, said he was surprised by just how much information could be gleaned from tiny fragments of eggshell no bigger than a fingernail.
Such estimates rely on the fact that eggshells contain carbonates — minerals made of carbon and oxygen atoms. Heavier forms of carbon and oxygen tend to cluster together more when the temperature is lower. So analyzing the amount of clustering reveals the temperature the eggshells formed in — that is, the dinosaur’s body temperature.
Both University of Calgary professor Darla Zelenitsky and Francois Therrien, a curator at the Royal Tyrell Museum, were part of teams that found troodon nests in southern Alberta. (Darla Zelenitsky)
Tagliavento, a postdoctoral researcher at Goethe University Frankfurt, said the technique can be accurate to within plus or minus 4 C.
In the new study, Tagliavento wanted to compare the eggshells of bird-like dinosaurs to modern birds and reptiles. He and his collaborators collected chicken eggs from a local farm, along with turtle and crocodile eggs, mostly from zoos. Knowing the the Royal Tyrell Museum in Alberta had a good collection of Late Cretaceous dinosaur eggs, he reached out to Therrien, who had collected troodon eggs himself in southern Alberta in the early 2000s.
Some had previously been collected in the 1990s by other paleontologists, including Darla Zelenitsky, an associate professor and paleontologist at the University of Calgary.
The nests and eggs were found in an area of Alberta that had a subtropical climate during the Late Cretaceous, but wasn’t as humid or forested as Dinosaur Provincial Park was at the time. Therrien said it would have been more open, with lower-growing vegetation, although grasses hadn’t yet evolved.
Zelenitsky said troodons would have roamed and hunted among birds, turtles, crocodiles, horned and duck-billed dinosaurs, and other small meat-eating bird-like dinosaurs.
Both Therrien and Zelenitsky ended up helping Tagliavento and co-authoring the study.
An illustration shows a troodon sitting on a nest. Fossil nests have been found with up to 24 eggs. A new study adds to evidence that such nests were shared by multiple females, and that troodons were warm-blooded and may have brooded their eggs. (Masato Hattori)
How birds and reptiles make and lay eggs
Therrien sent Tagliavento a small collection of fingernail-sized troodon eggshell fragments.
When Tagliavento first analyzed the dinosaur, bird and reptile eggshells, he found that they didn’t all follow the same pattern. It turned out that the measurements were affected not just by the temperature at which the eggshells formed, but how quickly.
Birds are very speedy egg producers. While a female has only one ovary, it can produce an egg a day. And within that day, the bird’s body can coat that egg with an eggshell, and lay it in a nest.
In contrast, reptiles have two ovaries, meaning they can produce two eggs at once. But they can’t make eggs as fast as birds. The reptilian process for coating the egg with an eggshell takes a week or two before the egg can be laid.
The researchers managed to correct for those differences by making some changes to their analytical technique.
In doing so, they saw that troodons produced eggs slowly like a reptile. Zelenitsky says a troodon female likely produced two eggs per ovary, every week or two. But its eggs were large (about the diameter of a goose egg, but twice as long), and unlike reptiles, researchers don’t think a troodon could accumulate eggs inside its body for weeks.
That means it would likely only lay four to six eggs per season — just a fraction of the two dozen eggs in a given nest.
This is a piece of eggshell from a troodon dinosaur. The fragments that were analyzed were roughly the size of a fingernail. (Darla Zelenitsky)
“Twenty-four eggs of that size looked a bit ambitious for a single individual,” Tagliavento said.
In fact, other researchers had previously suggested that troodon eggs were laid in communal nests.
“Now we have some analytical support to say that now yes, probably these troodons were sharing their nest,” Tagliavento said. “Which is a behaviour that now is observed in nature” among some birds such as ostriches.
Therrien said the combination of bird-like and reptile-like traits in such a bird-like dinosaur shows the transition from reptiles to birds was very gradual.
Just how warm-blooded was troodon?
From the eggshell analysis, the researchers were also able to read the body temperature at which the troodon eggs were formed.
Interestingly, they got two different results — some of the eggs formed at 42 C, similar to the body temperature of modern birds and a temperature previously reported for troodon.
But one appears to have formed at 29 C, which has also been reported for both troodon and related dinosaurs. That adds to evidence that troodon may have been able to lower its body temperature like some birds in order to save energy.
He thought they therefore had two ovaries, unlike birds, although he thought they had a more bird-like reproductive tract, based on the shape of the eggs and their appearance under a microscope.
He had also proposed that troodon sat on their eggs to hatch them, an activity known as brooding. Varricchio says this idea has become less controversial since then due to growing evidence.
In an email, he said the body temperatures found in the new study “would be consistent with brooding as we argued.”
But he said it was “curious” that the researchers found two different body temperatures, and he questioned whether an animal would produce an egg while trying to conserve energy by lowering its body temperature.
Eggshell analysis has great potential: researchers
Varricchio said the eggshell analysis technique used by the researchers holds great potential, but is still early in its application.
“I expect we will see many more eggshell and other fossil studies using this technique in the near future.”
An illustrated reconstruction of troodon, shows that it had feathers, and scientists believe it to be extremely bird-like. However, the new study shows it had a reptile-like way of producing eggs. (Alex Boersma/PNAS)
Tagliavento noted that in general, long-extinct animals such as dinosaurs don’t leave behind much more than fossil bones. “They don’t really give access or full access to the original biology.”
He said the eggshell analysis gives them “a window into these dinosaurs’ biology using something that before our work, we didn’t really imagine we could.”
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
