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Re: Horner and Goodwin on Triceratops
Jamie Stearns wrote:
I don't really see a lot of good ways to classify the various
ceratop(s?)ids, myself. On one hand you have those who would make up new
species for every minor horn/frill variation,
That used to be an issue, especially with the erection of new species of
_Triceratops_ and _Monoclonius_. This is not so much of a problem these
and on the other, there are those who would dump everything into one
species and cite "individual variation" to explain away the differences.
I would say that ontogeny rather than individual variation per se may
explain away certain differences. For example, Sampson et al. (1997)
presented a strong case that _Brachyceratops_ and _Monoclonius_ represent
subadult specimens of other centrosaurines_. More recently, Norell and
Makovicky (2006) suggested that _Platyceratops_, _Lamaceratops_ and
_Magnirostris_ may all fall within the range of ontogenetic variation
observed (or inferred) for _Bagaceratops_. (BTW, I'm not advocating the
latter hypothesis; I'm just drawing attention to it as an example of
differing viewpoints on taxonomy.)
I seem to recall horridus and prorsus were mainly separated on the basis of
the nasal horn being anteriorly curved in prorsus, posteriorly curved in
I'm not sure this was one of the characters used to separate _T. horridus_
and _T. prorsus_, although the curvature of the brow horns and relative
length of the nasal horns were cited.
Briefly, the characters were:
Length of the nose horn core (longer in _prorsus_);
Length of the rostrum anterior to the nasal horn core (longer in _prorsus_);
Length and angle of the orbital horn cores (shorter and more anteriorly
inclined in _prorsus_ - 60 vs 90 degrees relative to the horizontal);
Presence of frontal fontanelle (present in _horridus_ but not _prorsus_);
Dorsal border of lower temporal fenestra (jugal in _horridus_, squamosal in
So Forster used more than just the size and angle of the horn cores to
separate the two _Triceratops_ species.
similar to the situation of apertus/nasicornus in Centrosaurus [snip] Could
this mean Centrosaurus species ought to be reevaluated as well?
Most _Centrosaurus_/_Monoclonius_ species have already been synonymized with
_C. apertus_, including _dawsoni_, _flexus_, _nasicornis_ and
_longirostris_. The species _C. brinkmani_ was recently erected by Ryan and
Russell (2005), based on differences in horn core morphology and frill
ornamentation between it and _apertus_; but these characters appear to fall
outside the range of variation seen in _apertus_.
David Marjanovic wrote:
Yes, it should be, but it isn't. The ICZN now forbids the correction of
"incorrect latinizations" and the like as "unjustified emendation", so we
are stuck with what some call a "barbarism".
"Barbarism" is the word. Recent Chinese fossil bird papers in particular
are fertile ground for badly named families. Here, incorrect latinization
takes a back seat to bad spelling. Hopefully we won't be stuck with names
like Aberratiodontuidae (from _Aberratiodontus_), Gansuiornithidae (from
_Gansus_) and Yandangithidae (for _Yandangornis_) forever.