Ceratopsids are really cool guys. With all those freakin' horns, stouty and rhino-like bodies, parrot-like beaks and long and perforated skulls they look very strange. The closest thing to some anti-diluvian monster, I think.
Well, there isn't any better example of ceratopsid than Torosaurus. Yeah, I know, it COULD be the mature form of Triceratops, the most iconic of them all, but...I'm not quite convinced yet. There are some un-explained things in this theory and...We'll just see. For now, I prefer to separate these species.
So, here are some details about the portrait. Since there are confirmed patches of Triceratops's skin showing quill knobs, I decided to put 'em in this animal as well. Not very big ones, just something to act as a reminder. New artistic meme as well? Who knows.
An interesting thing is also the choice of colours of the face. I followed the Hone et al. paper about mutual sexual selection and amalgamed with the visual black and white alert design of the oryx. I think it could be a very usefull parallel. food for thought.
And...Well, this is it. Ah no, another thing: dewlap. I think it's a very cool thing for ceratopsians. They make 'em more glorious and mighty. An ispiration took from some modern bovids.
Torosaurus (commonly mistranslated as "bull lizard") is a genus of ceratopsid dinosaur that lived during the late Cretaceous period (late Maastrichtian stage), between 70 and 65 million years ago. It possessed one of the largest skulls of any known land animal. The frilled skull reached 2.6 metres (8.5 ft) in length. From head to tail, Torosaurus is thought to have measured about 9 m (30 ft) long and weighed 4 to 6 tonnes (4.4 to 6.6 tons).
Coloured with Pantone. Based on oryx, african elephant and modern cow.
References: G. S. Paul, Lukas Panzarin
Enjoy it!
PS: Sorry for the colours's quality, bad scanner
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Sta.sh
I also disagree with Jack Horner's theory about lumping Torosaurus into Triceratops. There are many problems with that theory, here are just a few:
1. The change is too radical for an animal that is no longer juvenile
2. Torosaurus is far rarer than Triceratops, too rare to simply be the same animal a few years older. 90% of Hell Creek's large herbivores are Triceratops, Torosaurus forms less than 1%.
3. Torosaurus has way more epoccipitals than Triceratops - and not only that, their numbers are far more variable in Torosaurus (from 30 to 37), while Triceratops always has exactly 17.
4. The Milwaukee specimen of Torosaurus has larger skull (including jugals) than Triceratops, but much smaller postcrania. Doesn't make sense why an adult animal's individual bones would be smaller than those of a "juvenile". Of course Horner doesn't specify if his 30-footers are really juvenile Triceratops or middle-aged adults, he just claims Torosaurus are "old adults". Ok whatever.
5. Beak shape in complete skulls is radically different - Triceratops had an eagle beak, Torosaurus has a much less curved "condor" beak that slopes downwards.
6. Nasal horn position (and snout/beak length ratio) differs between Torosaurus and triceratops. Torosaurus has shorter post-nasal-horn snout and longer beak. No ceratopsian is known to radically change beak shape or beak/snout ratios when reaching maturity.
7. The only Triceratops specimen that shows even remotely Torosaurus-like snout proportions and horns is the T. eurycephalus type skull, which is a very old adult with reabsorbed frill studs but NO fenestrae in the frill! This may be the most basal Triceratops species, close to a fork with Torosaurus.
8. There appears to be ontogenic variation within Torosaurus itself! The Yale specimen, the MOR specimen, the Denver specimen all show a great deal of variation in epoccipital reabsorbment and horn curvature. Indicating that Torosaurus is its own creature that underwent ontogenic changes of its own. Either that or Triceratops are still changing shape all the way to senility.
9. There are other ceratopsids close to Triceratops (like Eotriceratopsn Nedoceratos, and Ojoceratops) that don't fit comfortably in any part of Horner's ontogeny sequence. Nedoceratops has an odd mix of features that are only found individually in Triceratops of completely different ages, as well as having a high horn angle completely inconsistent with the forward curvature as well as the skull's advanced ontogeny, if one were following Horner's theory to its logical conclusions. Its squamosals don't look like anything known in Triceratops or Torosaurus.
10. The beak of the YPM skull, as well as the horn tips and rear frill of the MOR skull and most of the Milwaukee specimen skull have been incorrectly reconstructed to look like Triceratops. Also the MOR skull has a huge nasal boss in place of a horn, which is not consistent with anything seen in Triceratops.
11. All the Torosaurus specimens have relatively straight slender horns, not the thick robust forward-curving horns of mature Triceratops. In fact the closest thing to a Torosaurus brow horn among most Triceratops is adolescents or young adults of Triceratops which have barely attained the double curve stage, let alone the strong forward curve stage of mature Triceratops horridus and prorsus.
So did mature Triceratops just straighten out their horns a SECOND time and make them longer and slimmer after having already absorbed the tips and thickened the bases, all to become Torosaurus? I doubt it.
Oddly enough the only mature Triceratops that has horns anything like Torosaurus is T. eurycephalus, which is already a very old adult and shows no signs of fenestration, and has a far smaller head and frill than Torosaurus despite its age. Apparently T. eurycephalus did not reabsorb its horn tips or curve the horns strongly forward as an old adult, which makes it more similar to Torosaurus than the other Triceratops species. But it's clearly NOT the same animal as Torosaurus since its frill is unfenestrated despite having completely absorbed epoccipitals typical of a very old individual, as well as having far fewer epoccipitals than any Torosaurus.
Looks to me like instead of Torosaurus and Triceratops being ontogenic stages of the same genus, we see two genera with a common ancestor. And T. eurycephalus is one of the most basal descendants of that ancestor, it still retains some basal traits common to both it and Torosaurus as well as other more basal chasmosaurines, i.e. the lack of radical reabsorbment and curvature change in the orbital horns, long low snout, distinct geometric twin loci in the frill (i.e. a frill that's not so rounded) and so on. For some visual links backing up my insights, click here: [link]
(1) Why would an animal go through such a dramatic change in skull morphology after it's already fully mature?
(2) The animals have notably different numbers of epoccipitals; Triceratops have no more than 17, while in Torosaurus, they range in the thirties. Some have attributed this to "splitting", but no such phenomena has been observed in any other ceratopsian.
(3) Prior to the theory, Torosaurus has almost always been portrayed as a notably smaller animal than Triceratops, with the former barely exceeding 6 tons, and the latter reaching nearly 10 tons. If the theory were true, then shouldn't the size ranges be in reverse?
It was probably as big as Triceratops itself since the enormous skull, but to say if it was a little bit smaller or a little bit larger we just have to wait to find new specimens