centrosaurini – Nix Illustration

Ceratopsian Month #20 – Styracosaurus albertensis

The last centrosaur for this month is one of the most distinctive and recognizable of all ceratopsians – the elaborate Styracosaurus (“spiked lizard”).

Known from Alberta, Canada, about 75 million years ago, it was part of the Centrosaurini branch of the centrosaur evolutionary tree, closely related to both Centrosaurus and Coronosaurus. Many fossils have been found in several different bonebeds, including some nearly complete skeletons with body lengths of around 5.5m (18′).

There was a lot of variation in the frill ornamentation between different Styracosaurus individuals. They could have either two or three pairs of very long spikes at least 50cm long (19″), along with various smaller hooks, knobs, or tab-shaped projections.

The long nose horn was also very variable between specimens, with some pointing slightly backwards, some being straight, and others pointing forwards. Juveniles are known to have had small pointed brow horns which became even more reduced in adults.

Tomorrow we’re moving on to the chasmosaurs, so here’s the centrosaur evolutionary tree:

Ceratopsian Month #19 – Coronosaurus brinkmani

Coronosaurus (“crowned lizard”) was a very close relative of Centrosaurus – so close, in fact, that it was originally named as a second species of Centrosaurus itself, before being recognized as a separate genus a few years later.

Living around 77 million years ago, it was a medium-sized centrosaur about 5m long (16′4″). Multiple specimens are known from two bone beds in Alberta, Canada, with different ages represented. Juvenile Coronosaurus skulls looked very similar to juvenile Centrosaurus, only developing their own distinct ornamentation as they matured.

It had a slightly backwards-pointing nose horn, brow horns that curved out to the sides, and a pair of downward-curving frill spikes. Uniquely among all known ceratopsians, it also had large irregular masses of short spikelets at the top of its frill forming a distinctive “crown”.

Ceratopsian Month #18 – Centrosaurus apertus

Centrosaurus (“pointy lizard”) lends its name to the entire centrosaur group of ceratopsids – and also to a major branch within the centrosaur evolutionary tree, the Centrosaurini.

Known from Alberta, Cananda, around 76-75 million years ago, it grew up to about 6m long (19′8″) and is known from a huge number of fossils from thousands of individuals in gigantic bonebeds. These seem to represent enormous herds, making Centrosaurus one of of the most common dinosaurs in the region at the time.

It had a single large horn on its nose, which started off pointing backwards as a juvenile and changed shape as it grew, gradually hooking forwards. Two especially long spikes at the top of its frill curved strongly downwards, while its brow horns were reduced to small points.

Skin impressions are also known from one specimen, preserving a region around the right hip and upper leg, showing a pattern of small polygonal scales interspersed with larger rounded scales.