A dinosaur youngling belonging to the same group of beasts as Triceratops has been described in detail in the Journal of Vertebrae Paleontology. This ancient juvenile, which lived at the twilight of the age of the dinosaurs, will help to fill in several key evolutionary gaps that paleontologists have been puzzling over for some time.
The Ceratopsidae are one of the more immediately recognizable groups of dinosaurs. Characterized by sharp beaks and flamboyant horns and frills, these herbivores almost all lived in what is now Western North America right at the end of the Cretaceous period, 100 to 66 million years ago.
Chasmosaurus belonged to this group, and this new discovery represents an exciting moment for the research team, led by Prof. Philip Currie from the University of Alberta. “For the first time ever, we have a complete skeleton of a baby ceratopsid,” Currie said in a statement. Only its forelimbs are completely missing.
The 75 million-year-old fossilized Chasmosaurus was spotted in 2010 within the Dinosaur Park Formation in Alberta, Canada. In 2013, paleontologists completely unearthed it, and this week, they have described what is undoubtedly a rare specimen.
The adult variants are certainly distinctive, with large openings in their head ornaments earning them their appropriate name, which literally means “opening lizard.” Fully grown, they reach a size of up to 4.8 meters (16 feet) and a weight of roughly 2 tonnes (2.2 tons).
The juvenile Chasmosaurus fossil as seen from the side. Currie et al./JVP
This juvenile Chasmosaurus is an adorable 1.5 meters (4.9 feet) in length, and would have weighed less than 100 kilograms (220 pounds). It’s so young that its vertebrae had not properly fused, its limbs were not fully articulated (joined up), and it had a particularly short snout. Due to its ornamental opening being fully enclosed by a single bone, scientists have deduced it is likely a species called Chasmosaurus belli.
Not only was its ornamental frill predictably smaller than that of an adult, but it was also a different shape. The back isn’t broad and squared off as would be expected, and also narrows towards the back.
Just by having a juvenile Chasmosaurus, paleontologists will be able to track how the species grows over time as it matures into an adult. “We've only had a few isolated bones before to give us an idea of what these animals should look like as youngsters, but we've never had anything to connect all the pieces. All you need is one specimen that ties them all together. Now we have it!”
One major mystery remains, however: What was the purpose of the frill? Paleontologists note that the large opening would have made it rather useless in combat, so it may have been that it was used to regulate its body temperature, or that it was perhaps part of a sexual selection behavior designed to attract a mate.
Sadly, this 3-year-old dinosaur may have met an unfortunate end, probably drowning during a failed river rescue. Thankfully, paleontologists have, in a manner of speaking, brought it to life.