I love the late Cretaceous! It used to be a big mystery when I was a kid, and there was actually a lot of disagreement between scientists about the evolution of raptors and birds. Evidence has been rolling in for the last 30 years, and there are just so many cool pre-birds (that’s what I call them, most scientists would probably have a better name).
This is Citipati. They were huge (emu sized). At least four Citipati specimens have been found in brooding positions, the most famous is a large specimen nicknamed “Big Mamma” found in the Gobi Desert. All of the nesting specimens are situated on top of egg clutches, with their limbs spread symmetrically on each side of the nest, possibly-feathered front limbs covering the nest perimeter. This brooding posture is found today only in birds and supports a behavioral link between birds and theropod dinosaurs.
They are in the genus oviraptorid, or egg-theives, but they were totally misnamed at first. Oviraptor was originally presumed to have eaten eggs, based on its association with a fossilized nest thought to belong to Protoceratops. The discovery of actual nesting specimens of Citipati with the same types of egg showed that they were likely brooding the eggs, not feeding on them.
1. Citipati brooding behavior
2. Big Momma
3. Big Auntie
4. close up
5. A 1922 illustration incorrectly showing reptilian-like protoceratops guarding “their” eggs from the Citipati.
Awww, shucks. Look at these 15 tiny dinosaur babies crowded into a nest. They are called Protoceratops andrewsi, a sheep-size herbivore that lived about 70 million years ago that’s known for the frill at the back of its head. Researcher David Fastovsky, a vertebrate paleontologist at the University of Rhode Island, says that they were probably overrun by a migrating sandstorm in the Gobi. The environment was as harsh 70 million years ago as it is today.
What is totally cool is that this evidence suggests that parents actually took care of their babies (think birds) rather than abandoning them after laying them (think turtles).
This 70 mya dinosaur egg is from a titanosaur, considered one of the most massive of all dinosaur species ever. It contains the fossilized cocoons of wasps! Modern day wasps are well known for laying their eggs inside dead animals, but this is the first piece of evidence of similar behavior in ancient wasps.
The end of the Cretaceous was marked by a catastrophic meteor impact that wiped out the non-bird dinosaurs (called the K-T boundary). Turtles also survived the mass extinction because of their slow metabolisms and aquatic lifestyles (land turtles did not survive the extinction). The tough little turtles can survive by eating almost nothing and go into a state of near suspended animation until food opportunities present themselves.
This is a photograph of the Hell Creek Formation in North Dakota where fossils of dinosaurs and turtles have been collected. The K-T boundary is located where the yellow sand meets the gray mudstone.
Velociraptors were nocturnal, from a report out today in the journal Science. The researchers examined the scleral rings of more than 160 living species, including birds and reptiles, each with known activity patterns — some that are active at night, others during the day and still others that can swing either way. The structure of the velociraptor’s ring matches up to those that are nocturnal. Surprising, but makes total sense. Read the study here : http://www.sciencemag.org/content/early/2011/04/13/science.1200043