paleontologists uncover the tiniest pachycephalosaurid dinosaur

[sauroid]

http://phenomena.nationalgeographic.com/2016/03/30/paleontologists-uncover-the-tiniest-bonehead/#.Vvwa6l56yXw.facebook

also quoting Jack Horner about the issue
"Up until about 2009, paleontologists identified three different pachycephalosaurs from the Hell Creek Formation. There was a small, flat-headed form called Dracorex, a dome-headed mid-size species with large spikes called Stygimoloch, and the classic, large Pachycephalosaurus. But in that year Goodwin and Jack Horner proposed that Dracorex and Stygimoloch were really just immature Pachycephalosaurus, the differences in their skulls being signs of growth rather than different species. Here's where the baby skull comes in. The stubby points on the bone from the back of the skull, the squamosal, are clustered in the same way as "Dracorex," "Stygimoloch," and some adult-stage Pachycephalosaurus skulls. These spikes became set very early in life. Likewise, the flat bone from the skull roof shows ornamentation similar to that of "Dracorex" as well as the beginnings of a "void space" inside from the beginnings of dome growth. So even though some aspects of skull ornamentation changed throughout the growth of Pachycephalosaurus, the anatomical groundwork was already set in place when these dinosaurs were juveniles."

[Doug Watson]

Mother pachycephalosaurs must have been very thankful that they were oviparous.

[Pachyrhinosaurus]

It's been a while since the article, but I was shopping around for a stegoceras skull cast when I found this:

I don't know how much is reconstruction, but it says that the skull is still being cast.