New fossil evidence changes everything we knew about dinosaur evolution

A study of dinosaur egg fragments found in Western Canada has fundamentally changed everything paleontologists thought they knew about how prehistoric dinosaurs evolved into today's modern birds. 

Southern Alberta was a hotbed of dinosaur activity seventy-five million years ago and at some point a large river flooded, burying a number of freshly laid eggs that wouldn’t be discovered until fairly recently according to CBC’s Emily Chung,

Only fragments of the buried eggs survived to today, but that was enough to determine that they were laid by an ancient troodon, a meat-eating Emu-sized dinosaur that was warm-blooded and had a body temperature that hovered around 104° Fahrenheit according to the new study. 

Photo by Bryan, Own Work, Wiki Commons

The fragments were eventually studied by a team of researchers and they revealed the troodon that laid the eggs had a very slow egg development process based on its body temperature, a process rather similar to reptiles like today’s crocodiles according to CBC News. 

“We were able to figure out the dinosaur produced its eggs very slowly, which is typical of modern reptiles,” explained Darla Zelenitsky, one of the authors of the study. 

Photo by Twitter @ucalgaryscience

According to the study’s authors, they were trying to better understand how some biological processes like those of reproduction, nesting, and body temperature changed over time as prehistoric dinosaurs evolved into today’s modern birds. 

Mattia Tagliavento was the lead author of the study and he used a process known as dual clumpedisotope thermometry to reveal the body temperature of the dinosaur which laid the egg fragments, inadvertently also discovering a wealth of information about its reproductive system. 

Photo by Twitter @Clumpy_Tag

"So essentially, from an eggshell… we were able to get and deduct information about their reproductive system and also their behavior," Tagliavento said according to CBC. 

From an egg fragment no larger than a thumbnail, Tagliavento and the other study authors not only discovered the troodons average body temperature but also that the dinosaur probably couldn’t hold a large number of eggs in its body. 

The egg fragment was found among the remains of 24 other eggs and the evidence from the scientific data would suggest that the one troodon couldn’t have created so many eggs in one nest at any one time, meaning the reptiles were communal nesters. 

"Twenty-four eggs of that size looked a bit ambitious for a single individual," Tagliavento said about the nest where the troodon eggs were found. "Now we have some analytical support to say that now yes, probably these troodons were sharing their nest."

Photo by Twitter @AlexBoersma_Art

Because of the dinosaur's internal temperature, the study’s authors believe it couldn’t have acquired the fast egg-producing qualities of modern birds. Data showed the reptiles only had two ovaries with a limited ability to produce eggs.

The discovery that ancient troodons were communal nesters is a big one. Today’s modern ostriches are communal nesters according to Tagliavento, so it could mean that communal nesting behavior goes back much further than biologists previously thought. 

“It’s possible that some mothers congregated together to build communal nests and lay all their eggs, and then share duties of guarding and brooding all the eggs in turns,” said study co-author Francois Therrien according to Global News. 

According to Global News, the study’s authors were also able to reconstruct their troodon's physiology and metabolism in addition to their reproductive system and body temperature, expanding our understanding of the dinosaur as well as its descendants. 

Troodons are thought to be the ancestor of all modern birds according to Francois Therrien, and Global News reported that he still believes the troodon can tell us a lot about whether birds “inherit most of the characteristics from meat-eating dinosaurs.”

According to Interesting Engineering, troodons could reach as tall as six feet and had many of the characteristics of today’s modern birds, including things like hollow bones, feathery wings, and two legs. Unfortunately, the reptile's size prevented it from flying.