Tetrapod Zoology


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…

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.


  1. #1 Mad Doctor Harley
    April 25, 2009

    Well, I for one did enjoy our impromptu Ceratopsian Week! -shakes fangirl pompoms- I always learn something when I come here (which is why I come every day ^.^).

  2. #2 Hai~Ren
    April 25, 2009

    Damn, and I was so thrilled during those years, when the number of neoceratopsians from Late Cretaceous Mongolia/China suddenly shot up with Bainoceratops, Magnirostris, Lamaceratops, Platyceratops, and Protoceratops hellenikorhinus.

    I recall seeing pencil drawings of Protoceratops hellenikorhinus by Luc J. “Aspidel” Bailly and Øyvind M. Padron several years ago, back when the Dinosauricon was still in existence. In fact, I might still have the files stashed away somewhere. Lemme check.

    By the way, what’s the update on Breviceratops?

  3. #3 Lukas Panzarin
    April 25, 2009

    Darren…you probably mean Bagaceratops rozhdestvenskyi, not ‘kozlowski’ (which is the type species of Breviceratops) 🙂
    BTW, I don’t think Magnirostris is the same as Bagaceratops, as stated also by Kirkland and Deblieux 2007; the presence of postorbital horns (which are effectively present, and are not an effect of the dorsoventral compression of the skull; unfortunately the original description is very poorly illustrated, but new data are apparently forthcoming in the new Ceratopsian symposium book), the partecipation of the maxilla to orbital margin, a longer preorbital region , and relatively large nares are features not seen in Bagaceratops specimens(including Gobiceratops, Lamaceratops, and Platyceratop). Moreover, this taxon come from Bayan Mandahu, like P. hellenikorhinus, suggesting a somewhat different age from the Barun Goyot. About the new Udanoceratops skull…unfortunately I know just that the frill it’s “vaguely similar to juvenile/subadult specimen of protoceratops”…
    I think to be one the few that have made a life restoration of P. hellenikorhinus, if you want I can send you a copy.

    Kirkland J., Deblieux D. D., 2007. New centrosaurine ceratopsians from the Wahweap Fm., Grand Staircase-Escalante National Monument, southern. Ceratopsian Symposium Short Paper, Abstract, and Programs: 90-96

  4. #4 Zach Miller
    April 25, 2009

    I’d like to see your take on it, Lukas. I will also try my hand at a restoration. Questions, though: is the back of the frill really that curved, or is that a preservational artifact? Does this curvature show up consistently? Also, has the skull been squashed front-to-back at all? The rostral looks a little shoved inward (and virtually nonexistant).

  5. #5 Tommy Tyrberg
    April 25, 2009


    There is any number of archival copies of Dinosauricon at:


    so the image can probably be found there.

  6. #6 Dr. Nick
    April 25, 2009

    I’ve very much enjoyed obscure ceratop_ian week, too! Thanks, Darren!

    (most people would prefer the (technically incorrect, apparently) alternative spelling Bagaceratopsidae)

    Yes, “Bagaceratopidae” is the correctly derived term, for the following reason: the Greek term for ‘face’ is actually op, not ops. The -s in ops is a separate meaningful element (the technical term is “morpheme”) that means basically ‘the noun I’m attached to is singular and is either the subject of its clause or a predicate nominal’. The -s suffix only goes on the ends of nouns, never in the middle.

  7. #7 Jura
    April 26, 2009

    Yes, “Bagaceratopidae” is the correctly derived term, for the following reason: the Greek term for ‘face’ is actually op, not ops. The -s in ops is a separate meaningful element (the technical term is “morpheme”) that means basically ‘the noun I’m attached to is singular and is either the subject of its clause or a predicate nominal’. The -s suffix only goes on the ends of nouns, never in the middle.

    Oh good, I thought I was the only one left who preferred the correct spelling for ceratopians. 🙂

  8. #8 Allen Hazen
    April 26, 2009

    “Coronosauria = the Protoceratops + Triceratops clade”

    “Corona” is Latin for CROWN. Did the thinking behind this name go something like “This group is the apex or, umm, crown of ceratop(s)ian evolution so we’ll call it… What’s that? Yes, of course, “crown group” is defined in terms of EXTANT taxa, but nobody studies Latin any more so they won’t notice if call them the Corona group.”?

  9. #9 Hai~Ren
    April 26, 2009

    Tommy Tyrberg: Actually, I went to dig around in my external hard drive and found the relevant couple of pictures stashed away. I’ve sent them over to Darren, maybe he’ll able to share them.

  10. #10 Andreas Johansson
    April 26, 2009

    Re: Coronosauria, I’ve been assuming it refers to “crownlike” frills.

  11. #11 William Miller
    April 26, 2009

    Two nasal horns? Awesome! I wonder why that line didn’t produce anything bigger? (Or maybe it did, and the fossils just haven’t turned up yet?)

  12. #12 David Marjanović
    April 26, 2009

    Oh good, I thought I was the only one left who preferred the correct spelling for ceratopians. 🙂

    The ICZN forbids any correction of Ceratopsidae (and Ceratopsinae) and Protoceratopsidae. I’m not sure if it governs Ceratopsia…

    That said, all temnospondyl families and superfamilies in -opsidae and -opsoidea were switched to -opidae/-opoidea in the 1990s, and everyone has followed that. And when people finally noticed that Varanopseidae* was nonsensical, they didn’t switch back to the original Varanopsidae (which hadn’t been used for 50 years or something**), but coined the new Varanopidae, which has been used ever since.

    * Someone (understandably) thought that it would have been better if Varanops “goanna face” had been named “Varanopsis” “goanna shape/aspect”, and then went on to derive Varanopseidae from that fictional name. I think it was H. F. Osborn, which explains why he got away with that kind of chutzpa (and that till long after his death). I’ll need to check. Hm… no, probably it was Olson…
    ** So perhaps it’s a nomen oblitum, but this isn’t mentioned in the paper that argues for using Varanopidae, and the name is still attributed to the same authors.

    BTW, is Zatrachydidae or Zatracheidae linguistically correct (based on the temnospondyl Zatrachys serratus)? I’ve seen both in the literature, with the latter spelling being only a few years old.

  13. #13 Lars Dietz
    April 26, 2009

    It’s even worse with sandgrouse, which I’ve seen called Pteroclidae, Pterocleidae, Pteroclididae, and Pterocletidae. Part of the problem here is that nobody seems to know what Pterocles is supposed to mean.

  14. #14 David Marjanović
    April 26, 2009

    “Glory of flight”?

  15. #15 Mike from Ottawa
    April 26, 2009

    I loved Ceratopsian Week. Learned lots of new stuff, mostly how little I knew, but that’s par for the course at TetZoo!

  16. #16 Jaime A. Headden
    April 26, 2009

    David, Darren,

    Both of you or maybe just David’s comment above (#12) lead me to suspect that taxonomy in this case is as flexible as the Queen’s English, and I know David knows better, but the ideology of correctness perhaps subsumes the taxonomy as it stands:

    Ceratopsia is the correct spelling, because this is the established spelling. It is not the correct Greek, but it is the correct taxonomic spelling. The same holds true for Leptoceratopsidae, Ceratopsidae, Protoceratopsidae, and in a twist, Bagaceratopidae.

  17. #17 Lars Dietz
    April 27, 2009

    “”Glory of flight”?”

    I’ve found the original description on Google Books, http://tinyurl.com/dzfk9x and Temminck wrote that the name meant that there was something special about their wings. So your idea on the meaning of the -cles element was probably correct. So what does this mean for the family name? I don’t know much about Classical Greek grammar, but I think there should be no consonant at the end of the word stem. So is it Pteroclidae, Pterocleidae, or even Pterocliidae? Each of these (and every other possible variation I could think of) gets some Google hits.
    Anyway, back to the original topic, this was a great post about these ceratop(s)ians. About the only thing I knew about them before was their names. Two nasal horns… I wonder why this isn’t more widely known.

  18. #18 David Marjanović
    April 27, 2009

    but the ideology of correctness perhaps subsumes the taxonomy as it stands:

    What do you mean by “subsume”?

    So what does this mean for the family name?

    How would the sons of Hercules (Herakles) be called?

  19. #19 Christopher Taylor
    April 27, 2009

    How would the sons of Hercules (Herakles) be called?


  20. #20 Lars Dietz
    April 28, 2009

    So it looks like the correct name is Pterocleidae, which seems to be one of the little used variations. Those that get by far the most Google hits are Pteroclididae and Pteroclidae.

  21. #21 Dr. Nick
    April 29, 2009

    From Christopher Taylor:

    How would the sons of Hercules (Herakles) be called?


    …except that the “diphthong” ei was probably already pronounced as a long i in late Classical Greek and was usually transliterated as such in Latin.

    So the spelling “Pteroclidae” is legit. The wrinkle is, the long i in the second-to-last syllable would have carried the stress, and since English usually stresses the syllable that would have been stressed in Latin, the English pronunciation should arguably be “teh-roh-KLY-day” (/,tE.ro.’klaI.deI/) rather than the expected “teh-ROCK-lih-day” (/tE’rak.lI.deI/).

  22. #22 Dr. Nick
    April 29, 2009

    From David M.:

    BTW, is Zatrachydidae or Zatracheidae linguistically correct (based on the temnospondyl Zatrachys serratus)? I’ve seen both in the literature, with the latter spelling being only a few years old.

    If Zatrachys is ‘very rough’, then “Zatracheidae” is etymologically correct.

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