Posted by I never planned to do a whole week on ceratopsians: the initial idea was just to recycle some of those field guide texts in order to save a bit of time. But, oh well, Ceratopsian Week took on a life all its own. To finish things off, we’re going to look at some tremendously obscure ceratopsians: they’re reasonably familiar to dinosaur uber-nerds/dinosaur experts, of course, but are unheard of outside of the dinosaur community.
We begin with Protoceratops hellenikorhinus Lambert et al., 2001 [shown here] from the Campanian of Bayan Mandahu, Inner Mongolia. P. hellenikorhinus is similar to the far more familiar and better known P. andrewsi, but is larger (skull lengths are 80 cm vs c. 50 cm), has a straight (as opposed to curved) ventral margin to the lower jaw and, most obviously, has two, parallel nasal horns. The specimens referred to P. hellenikorhinus are actually pretty variable in nasal horn morphology however, and some lack horns entirely. This was interpreted as sexual dimorphism by Lambert et al. (2001). Not only are the horns odd in being twinned, they’re also surprisingly high up on the snout – in fact, they’re virtually set right above the eyes. Lambert et al. (2001) noted that the horns were therefore poorly placed for combat, and that perhaps a role in display was more likely. Incidentally, the species name means ‘Greek nose’, as ‘with its elevated and angular snout, this species has some kind of Greek profile’ (Lambert et al. 2001, p. 7). I’m familiar with the term ‘Roman-nosed’, but hadn’t realised prior to reading this paper that ‘Greek-nosed’ is also a recognised term.
Despite the fact that it has two freakin’ nasal horns, Protoceratops hellenikorhinus has been all but ignored by everyone outside of horned dinosaur research, and I cannot recall ever seeing a life restoration, or a substantive discussion outside of the technical literature.
Magnirostris dodsoni You & Dong, 2003 was named for a near-complete skull, also found at Bayan Mandahu [shown here, from You & Dong (2003)]. Included by You & Dong (2003) within Protoceratopsidae, it shares a subsidiary fenestra ventral to the external naris with Bagaceratops rozhdestvenskyi and hence was regarded as particularly close to that taxon. Alifanov (2003) later coined Bagaceratopidae (most people would prefer the (technically incorrect, apparently) alternative spelling Bagaceratopsidae) for the group that (supposedly) includes Bagaceratops and some close relatives, so Magnirostris would be in here too if (1) it were a valid taxon, and (2) there was a clade that warranted the name Bagaceratop[s]idae.
And… is Magnirostris a valid taxon? Almost certainly not: the two features supposed to distinguish Magnirostris from other ceratopsians were never satisfactory. The dorsally projecting lump you can see on the postorbital (the bone behind the orbit) is, according to You & Dong (2003), an ‘incipient orbital horn core’. However, even from the figures in the paper it’s pretty obvious that the bones over the orbit (frontals and prefrontals) have been squashed downwards, leaving the more robust postorbital region and nasal bones projecting upwards. The ‘orbital horn core’ is, I suggest, a product of deformation, and Makovicky & Norell (2006) later noted that the alleged horn core was an ‘artifact of preservation’ (p. 28). The other diagnostic feature of Magnirostris – an elongate and robust rostral bone – is not convincing either: the size and shape of the rostral varies within other ceratopsian species, and what’s present in Magnirostris isn’t all that different from the condition in Bagaceratops [the rostral is unique to ceratopsians and forms the tip of the upper jaw, a role normally played by the paired premaxillae]. The Magnirostris rostral does look longer and larger than that of Bagaceratops, but that’s mostly because the snout has been squashed and stretched during fossilisation. Goodbye Magnirostris: it’s almost certainly a good-sized Bagaceratops specimen.
Among other alleged ‘bagaceratopids’, we have Platyceratops tatarinovi Alifanov, 2003 from the Barun Goyot Formation of the Nemegt Depression, Mongolia [shown here, frlom Alifanov (2003)]. Alifanov (2003) argued that Platyceratops differed from Bagaceratops (and other supposed ‘bagaceratopids’) in its proportionally narrower skull, taller nasal horn, and in various other details. However, the Bagaceratops rozhdestvenskyi holotype is a juvenile with a skull just 19 cm long: the Platyceratops skull (which is about 33 cm long), with its taller nasal horn and slightly different proportions, is so outstandingly similar that it almost certainly represents a growth stage of the same species. The same goes for the small Lamaceratops and Gobiceratops too (Alifanov 2003, 2008). In fact, we probably now have a very good ontogenetic series for Bagaceratops, though it’s obscured in part by an unrealistic taxonomy [life restoration of Bagaceratops rozhdestvenskyi below by Brian Franczak].
Bagaceratops was close to Protoceratops: both are non-ceratopsoid coronosaurians, and hence closer to ceratopsids than are the leptoceratopsids (Coronosauria = the Protoceratops + Triceratops clade; Ceratopsoidea = all coronosaurians closer to Triceratops than to Protoceratops).
And that about wraps it up. I hope you enjoyed Ceratopsian Week: for all the Tet Zoo ceratopsian articles so far see…
- Tet Zoo picture of the day # 11 (or, speculations on omnivory in ceratopsids)
- Pentaceratops: that’s quite the skull
- SVPCA 2007: dinosaurs attack (includes stuff on Psittacosaurus)
- A month in dinosaurs (and pterosaurs): 3, Minotaurasaurus and giant chasmosaurines
- Udanoceratops tschizhovi, the basics
- No-one talks about Anchiceratops, boo hoo
- Zuniceratops and the early acquisition and alleged dimorphism of ceratopsian brow horns
- A very alternative view of horned dinosaur anatomy
- Ceratopsian dinosaurs: cheeky or beaky?
Refs – -
Alifanov, V. R. 2003. Two new dinosaurs of the infraorder Neoceratopsia (Ornithischia) from the Upper Cretaceous of the Nemegt Depression, Mongolian People’s Republic. Paleontological Journal 37, 524-534.
- . 2008. The tiny horned dinosaur Gobiceratops minutus gen. et sp. nov. (Bagaceratopidae, Neoceratopsia) from the Upper Cretaceous of Mongolia. Palaeontological Journal 42, 621-633.
Lambert, O., Godefroit, P., Li, H., Shang, C.-Y. & Dong, Z.-M. 2001. A new species of Protoceratops (Dinosauria, Neoceratopsia) from the Late Cretaceous of Inner Mongolia (P. R. China). Bulletin de L’Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre 71-Supp., 5-28.
Makovicky, P. J. & Norell, M. A. 2006. Yamaceratops dorngobiensis, a new primitive ceratopsian (Dinosauria: Ornithischia) from the Cretaceous of Mongolia. American Museum Novitates 3530, 1-42.
You, H. & Dong, Z. 2003. A new protoceratopsid (Dinosauria: Neoceratopsia) from the Late Cretaceous of Inner Mongolia, China. Acta Geologica Sinica 77, 299-303.
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