Ornithischia versus Predentata

Do you feel that Ornithischia is a misnomer? Ornithischians don't really seem to have the birdlike hips that they're often identified as having, so... should we follow Bakker's example from 1986 and start using Marsh's Predentata? I've leaned towards this for awhile since a predentary is far more distinctive of the group from what I've seen as opposed to 'bird-like hips'

I think it further confuses the issue. Bakker likes to ressurect quaint terms from the past (see Brontosaurus). Ornithischians are a widely and universally accepted term. If you really want to nit pick, point out birds like Hesperornis with a predentary bone as well.

Still, at least it's accurate to say that ornithischians do have predentaries, it's not the same as saying they have 'birdlike hips' when they really don't

I'd also like to see a figure of Hesperornis' predentary, every skeleton and drawing of the skeleton I've seen so far in googling images seems to lack it (unless it's horribly small or something D:)

It is horribly small. As far as I can recall, there are 3 in existence. I've held and was going to cast the KU specemin. It fits into a small glass vial.

So it's vastly different from the structure in ornithischians, what was its purpose anyway?

Vastly? I wouldn't say that. Just because it is smaller in size doesn't mean it is not homologus. A keratin covered beak in front of a tooth bearing dentary.... Am I describing Hesperornis or Thescelosaurus?

Well, a predentary is not a keratin covered beak in front of a tooth bearing dentary (if so, then you could say oviraptorosaurs and many other beaked theropod dinosaurs had predentaries as well). It's a separate bone rostral to the dentaries, that replaces the functional symphysis between the dentary rami, and has a varied morphology between ornithischians themselves. I'm sure there's a great deal of difference between the 'predentary' of Hesperornis and Thescelosaurus.

Let's clarify here. Are you saying that the predentary is not a seperate bone in front of the tooth bearing dentary, as in ornithiscins, Hesperornis, and from what it looks like, Parahesperornis as well? Or are you contending that they were not covered in keratin? The thescelosaur skull that I'm working on now sure looks like it had a beak-type predentary, and it was seperate from the tooth bearing dentary.

Our two oviraptors (full description coming sometime soon) had beaks, yes, but no teeth in the maxilla, premaxilla, or dentary.

You say it is variable between ornithscians themselves, and I can see it, espescially in hadrosaurs as opposed to, say, nodosaurs or pachycephalosaurs. Why not choose a better all inclusive term, such as one that names lack of gastralia as a feature instead?

No, you basically implied that by typing: "A keratin covered beak in front of a tooth bearing dentary". A beak is a vague term usually (and often) referring to an edentulous area, from the way you were writing, it seemed to imply that you were treating a predentary as merely an untoothed portion of the dentaries. I never said anything of the sort, in fact, I even stated that it is a separate bone above: "It's a separate bone rostral to the dentaries". >.>

See above. I never said they weren't covered with keratin or even implied it.

See above. My point was to distinguish an edentulous and keratin covered portion of the dentary from a predentary given your quote above.

I might have contemplated that, but I'm not trying to create an entirely new name, just suggesting we might opt for a previously existing and more descriptive name. Additionally, there's variation even between basal ornithischians and basal members of some of the groups (especially ornithopods and ceratopsians). How is "Predentata" not all inclusive? All known ornithischians with relevant material show a predentary.

Ah. A bit of confusion there.

Back to the main issue. Changing widely accepted names of animals and groups of animals just because a researcher feels like it (Bakker) is silly. T. rex has about 3 different names that take precedence over its current one. That's why the ICZN uses the 100 year rule, which basically says a name used for over 100 years should be left alone. This pretty much locks in many of the older names, including and excluding most of Marsh (and Cope, and Leidy...)'s terms, no matter how quaint some modern researchers find them.

Personally I like ornithiscians as a name of a group. If, for nothing else, the history behind it. Now, as for how lame I think ornithiscians themselves are... that's another topic.

Two points: 1. The ICZN is outdated and will soon be replaced in the near future. 2. Ornithischians rock... jerk. >:

Hey now, just because I don't have love for your bird hips doesn't mean you have to resort to personal attacks.

ICZN is still the standard that everyone has to go by. Whatever replaces it should maintain the current pragmatic approach. Otherwise I want in on the free for all naming frenzy that follows its supposed demise. After all, I have at least 5 new species on the shelf in my lab. Sadly, only one is an ornithiscian.

OH NOES. INTERNET. SERIOUS. OH WAIT.

Keep it on topic, boys.

Just logged in here, to discover a commotion...

Certainly, real bird hips aren't homologous with the reversed ornithischian pubis, but obviously Seeley named Ornithischia originally for the resemblance to avian pelves., not becuase he thought Ornithischians were actaully birds. But these days, I can't think of anyone (in serious dinosaurology) who'd think about the 'birdiness' of the pelvis and it's shape when they think of Ornithischia. It's ideal if a name of a group describes a key character of the group but not nessessary. Anyway, this is still bourne out by Seeley's name, because of the general resemblence factor to bird hips (reversed pubes).

Thayer, your suggestion to ditch Ornithischia for Predentata because ornithischains have a predenta and not an avian pelvis has important implications for the naming of taxa. If i follow your line of argument, then taxa would be named for their ACTUAL CHARACTERS (eg Predentata) not RESEMBLED CHARACTERS (eg Ornithsichia). If you'd want to be fair, you'd have to get rid of pile of names from Falcarius ('sickle maker'), Ornithopoda ('bird feet'), Oviraptoridae (do we really know if a whole family of theropods were 'egg stealers') and even Brontosaurus wouldn't have a place here (did this animal really produced 'thunder'?)

Ones personal feelings for a name choice (Thayer, Bakker) are not enough to overthrow the established rules in place.

1) Simply, Ornithischia clearly has priority over Predentata; This is foremost and most important. Ornithischia has wide usage, Predenta doesn't, infact, i'd say Predentata should be classified as an ICZN 'forgotten' name, because it hasn't been used in any publication in the last 80 years.

2) Lets say, a very basal 'Ornithischian' was discovered without a predentary, then perhaps, Predentata could be brought back for a subset group of Ornithischia with predentary bones.
And incidently, does anyone know if Silesaurus has a predentary or not?