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Three New Neoceratopsians (Bagaceratopsidae Described)
Indirect thanks to Rusov Sergey and Mickey Mortimer for providing the two new
papers discussed here, beginning with:
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(5): 524-534.
Abstract:
"Two neoceratopsians, *Lamaceratops tereschenkoi* gen. et sp. nov. and
*Platyceratops tatarinovi* gen. et sp. nov., from the Barun Goyot Formation
(?Lower Santonian, Upper Cretaceous) of the Khulsan and Khermiin Tsav localities
(Nemegt Depression, Mongolia) are described. The new genera along with
*Bagaceratops rozhdestvenskyi* Maryanska et Osmólska, 1975 and *Breviceratops
kozlowskii* (Marya ska et Osmólska, 1975) are assigned to the family
Bagaceratopidae fam. nov. characterized by the fused nasals; the presence of the
nasal horn and large subnarial fenestrae posterior to the nares between the
premaxilla, maxilla, and nasal; and, probably, the development of undulating
ornamentation on the surface of the egg shell. The main evolutionary stages of
Asian neoceratopsians are discussed."
What is first obvious is that the taxon Bagaceratopidae is coined, notably
without the "s." Of the two new Barun Goyot taxa, both contemporaneous with
*Bagaceratops rozhdestvenskyi,* both appear remarkably similar to
*Bagaceratops*. Bagaceratopidae is diagnosed by: "Nares small. Lower temporal
fenestrae relatively large. Rostral bone flattened, with formation of carinate
upper edge. Nasals fused and forming projection (horn) shaped into cone or flat
crest. Ventrally, they connected to maxillae. Large subnarial fenestrae
located posterior to nares and bordered by premaxilla, maxilla, and nasal.
Preorbital depressions well developed. Frontals participating in formation of
upper orbital rim. Supraorbitals well-pronounced and connected to prefrontals
only. Postquadrate region of squamosals short. Predentaries narrow and high.
All teeth single-rooted. External surface of upper teeth with two depressions
unequal in area; one or two enamel folds formed in area of smaller posterior
depression, and two or three enamel folds formed in place of larger anterior
depression. Presumably, surface of egg shell with undulating ornamentation."
Bagaceratopidae is described as including *Bagaceratops rozhdestvenskyi,*
*Breviceratops kozlowskii,* and the two new species.
*Lamaceratops tereschenkoi* is represented by PIN 4487/26, a skull about 3/4
the size of the *Bagaceratops* holotype. The name refers to the Tibetan word
_blama_ (=lama), or "monk" + conventional *Ceratops,* and the species name
honors Dr. Victor Tereschenko, a paleoherpetologist who discovered the holotype
at Khulsan, Barun Goyot Formation. *Lamaceratops* is diagnosed by: "Ratio of
skull length to width 2.5. Length of upper temporal fenestra almost twice as
long as its width. Longitudinal orbital diameter one-forth as long as skull.
Subnarial fenestrae located in line with middle of nares. Area of nares almost
twice as large as that of subnarial fenestrae. Occipital length of parietal
approximately equal to its axial length. Rostral end of this bone less than
half as narrow as occipital end. Dorsal surface of parietal shaped into thin
medial crest passing onto frontals. Frontals paired. Their posterior edge
shaped like the letter W upside down. Anterior edge of these bones almost
circular. Frontals not forming a clear postorbital process nor orbital
constriction. Occipitally, nasals having incisure shaped like the letter U
upside down. Nasal horn small, conical, located rostral to anterior edge of
orbits. Ascending process of prefrontals lengthened dorsally and slightly
narrowed occipitally. Quadratojugal process of jugals large and U-shaped.
Quadratojugals relatively small and not contributing to the formation of the
border of lower temporal fenestra. Jugal process of postorbitals pointed.
Dorsally, squamosals positioned almost parallel to each other. Premaxillae
lacking teeth."
*Lamaceratops* is distinguished from *Bagaceratops* by: "by the circular
anterior edge of the frontals, the absence of orbital constriction and
postorbital process in these bones, the U-shaped quadratojugal process of the
jugals and the U-shaped incisure in the posterior edge of the nasal, the
presence of the medial crest on the posterior edge of the frontals, and the
quadratojugal not contributing to the formation of the lower temporal
fenestra[;]" from *Breviceratops* by: "the smaller size, a relatively narrow
skull and narrow upper temporal fenestrae, larger orbits, a short parietal
relative to the skull length, a lesser occipital expansion of this bone, the
dorsal surface of the parietal bone entirely shaped into a narrow crest passing
onto the posterior edge of the frontals, the presence of two frontals, a more
rostral position of the conical nasal horn, a weak occipital constriction of the
ascending process of the prefrontal, and a small angle at which the squamosals
are positioned to each other[;]" and from both by: "the relatively narrower
upper temporal fenestrae, smaller orbits, the narrower rostral edge of the
parietal compared to the occipital edge of this bone, the only weakly narrowed
ascending process of the prefrontals, the massive quadratojugal process of the
jugals, the less pointed jugal process of the postorbitals, and the absence of
teeth in the premaxillae."
*Platyceratops tatarinovi* is represented by PIN 3142/4, a skull about 1/4
larger than the *Bagaceratops* holotype. The name refers to the relatively short
face and level margin between rostroventral tip of the rostrum and the nasal
horn, and the species name honors Dr. Leonid Tatarinov, a paleoherpetologist.
The specimen was discovered at Hermiin Tsab (=Khermeen or Khermiin Tsav), Barun
Goyot Formation. *Platyceratops* is poorly preserved, typical of the locality,
notable for erosional condition of surface specimens. *Platyceratops* is
diagnosed by: "Ratio of skull length to width 1.5. Length of upper temporal
fenestra almost twice as long as its width. Longitudinal orbital diameter
one-fifth as long as skull. Nares almost half as large as subnarial fenestrae
and located in line with upper edge of these fenestrae. Parietals large; their
occipital edge approximately three times as wide as rostral edge and almost 1.5
times wider than axial length of these bones. Dorsal surface of parietal shaped
into narrow medial crest. Collar with large fenestra. Frontals very small and
paired, having W-shaped posterior edge, and lacking clear posterolateral process
and orbital constriction; their anterior edge circular and wider than posterior
edge. Nasal very narrow. Its posterior edge U-shaped. Nasal horn formed by
almost whole surface of nasal bone and shaped into flattened projection with
elevated rounded posterior region. Dorsally, ascending process of prefrontal
short and wide. Quadratojugal process of jugal large, U-shaped, and extending
beyond level of quadrate bone. Quadratojugals not contributing to the formation
of lower border of lower temporal fenestra. Jugal process of postorbitals
blunt. Squamosals positioned at angle more than 60° to each other."
*Platyceratops* is distinguished from other bagaceratopids by: "the stout
skull, large parietals, the presence of fenestrae in the parietal, small
dimensions of the frontals, W-shaped posterior edge of the frontals, the narrow
nasal, U-shaped occipital edge of the nasal, dimensions and shape of the nasal
horn, and the angle between the squamosals approaching 60°[;]" from
*Bagaceratops* by: "the relatively narrower skull, longer upper temporal
fenestra, weaker occipital expansion of the parietal, relatively longer axial
length of the parietal, the dorsal surface of the parietal entirely shaped into
the thin medial crest, preservation of two frontals, and the blunt jugal process
of the postorbital[;]" from *Breviceratops* by: "the smaller orbits, the broad
and short ascending process of the prefrontals, and the position of the
squamosal at relatively large angle to one another[;]" from both by: "the
circular anterior edge of the frontals, the absence of orbital constriction and
postorbital process of the frontals, the short and wide ascending process of the
prefrontal in dorsal view, U-shaped quadratojugal process of the jugals, and by
the quadratojugal not contributing to the formation of the lower border of the
lower temporal fenestra[;]" and from *Lamaceratops* by: "the less extended
skull, the position of the nares almost on level with the upper edge of the
subnarial fenestrae, relatively smaller orbits, a more expanded occipital edge
of the parietal, the narrowed posterior edge of the frontals, a larger nasal
horn, the relatively shorter ascending process of the prefrontal, and the blunt
jugal process of the postorbital."
Alifanov (2003) suggests that *Lamaceratops* and *Platyceratops* are close,
maybe sister groups, based on: "[...]the structure of the frontals, which are
characterized by the circular anterior edge, expanded orbital edge, and the
absence of postorbital processes; the U-shaped quadratojugal process of the
jugal; and the quadratojugals, which do not contribute to the formation of the
lower temporal fenestra."
The second paper (which I have not read):
You H.-L. &Dong Z.-M. 2003. A new protoceratopsid (Dinosauria: Neoceratopsia)
from the Late Cretaceous of Inner Mongolia, China. Acta Geologica Sinica
[English edition] 77:299-303.
Abstract:
"An almost complete skull, which was collected from the Late Cretaceous of the
Bayan Mandahu area in Inner Mongolia, China by the Sino-Canadian Dinosaur
Project, is described and assigned to a new genus of protoceratopsid dinosaur,
*Magnirostris dodsoni* gen. et sp. nov. This new taxon is distinguished from
other protoceratopsids by the robust rostral bone and the existence of incipient
orbital horn cores. The existence of an additional antorbital fenestra
indicates a close relationship between *Magnirostris* and *Bagaceratops.*"
Describes *Magnirostris dodsoni,* a skull from Bayan Mandahu, notable for the
very large rostral bone, a nasal horncore that lies nearly on the fronto-nasal
suture, a subnarial fenestra that is extremely enlarged, as in *Bagaceratops,*
prefrontals with a thickening of the dorsolateral rim that bears similarities to
orbital horncores, and a relatively large external naris. The postorbital/jugal
contact is broad rostrocaudally, and rounded ventrally rather than tapering; the
jugal "horn" angles laterally and caudally, acuminate at the level of the
quadratojugal when viewed from above, an arcuate fronto-nasal suture (bowed
rostrally), and a premaxilla that nearly contacts the lachrymal/prefrontal.
There are no premaxillary teeth. The squamosals, most of the quadrates, and
braincase are not preserved, and the skull is partially flattened in the caudal
region, resulting in a squished appearance laterally. (The primary illustration
of the skull is shown here:
http://www.sinofossa.org/sinosaur.htm#Magnirostris -- the website also notes
other recent discoveries, including a new ankylosaurid from Liaoxi Province that
looks a _lot_ like *Gastonia* and *Gargoyleosaurus,* so no wonder the thing will
be described by Kirkland and You.)
The etymology of the name is clear, referring to the large rostral bone and
honor Dr. Peter Dodson, friend and PhD supervisor to the primary author.
Some discussion:
Sereno (2000) synonymized *Breviceratops* (Kurzanov, 1990) into *Bagaceratops*
(Maryanska and Osmólska, 1975) on the basis of nearly identical anatomy curves;
if one would continue the growth curve of the latter through the larger form of
the former, one gets a single animal. What is problematic is that both
*Lamaceratops* and *Platyceratops* fit these curves and appear to be divergent
only in their relative positions on these ontogenetic trends, as described by
Maryanska and Osmólska (1975) and elaborated upon by Kurzanov (1990), who did
not consider *Breviceratops* fairly close to *Bagaceratops.* Ontogenetic trends
in *Bagaceratops,* observed through heterochrony, note that the skull becomes
broader and relatively deeper as the animal ages, as the nasal prominence
transforms into a longitudinal crest on the conjoined nasals. *Breviceratops*
shows a trend in juvenile to adult forms a generally conical nasal horn core,
and though an extremely adult specimen shows a bifurcate, rostrocaudally
elongated nasal horn, rather than conical, and this implies that the complex of
both taxa should be more closely evaluated to constituency of their hypodigm.
You and Dong (2003) describe a likely bagaceratopid with a very large rostral
that can be referred to Alifanov's Bagaceratopidae on the basis of 1) lower
temporal fenestrae relatively large; 2) nasals fused and forming projection
(horn) shaped into cone or flat crest; 3) ventrally, they connected to maxillae;
4) large subnarial fenestrae located posterior to nares and bordered by
premaxilla, maxilla, and nasal; 5) preorbital depressions well developed; and 6)
frontals participating in formation of upper orbital rim. This involves the
majority of diagnostic features; however, several of Alifanov's features are
plesiomorphies, including predentary shape, frontals participating in orbital
rim, short caudal limit of squamosal. The presence and position of supraorbitals
is considerably weak as a diagnostic feature, as this condition is not noted in
any other ceratopsian, and the presence of a palpedral (supraorbital 1 of some
authors) is plesiomorphically attached to the lachrymal or lachrymal/prefrontal
suture, or is absent; in juvenile *Bagaceratops* the palpedral is attached to
the prefrontal, the suture between prefrontal and lachrymal is unknown in
*Platyceratops,* and *Lamaceratops* does not preserve a palpedral, as in
*Magnirostris*; palpedrals are generally absent in neoceratopsians.
It would appear that, while the identification of species boundaries is
tenuous, the diagnoses are largely viable, and that these three new species
reflect the growing recovery of herbivore diversity in the Santonian-Campanian
of the Gobi Desert.
--Bagaceratopidae [Alifanov, 2003]
|--*Bagaceratops* [Maryanska and Osmólska, 1975]
|--*Breviceratops* [Kurzanov, 1990 (Maryanska and Osmólska, 1975)]
| (=*Bagaceratops*?)
|--*Lamaceratops* [Alifanov, 2003] (=*Bagaceratops* or
| *Breviceratops*?)
|--*Platyceratops* [Alifanov, 2003] (=*Breviceratops*?)
`--*Magnirostis* [You and Dong, 2003]
Alifanov (2003) does not regard, whether actively or passively, the research
of Makovicky (2001) on leptoceratopid systematics, though he cites
*Liaoceratops* which regarded this phylogeny, and refers to *Udanoceratops* as a
"protoceratopid;" he also uses "Ceratopidae" and "Protoceratopidae," which are
historically (and by priority) incorrect, however etymologically correct they
are; the ICZN does not permit revision of a family name because someone
inadverdently, 50+ years ago, included an "s" where there _shouldn't've_ been,
and the applied changes are erroneous in practice. Thus, he refers to
*Turanoceratops* as a "ceratopid." No reflection is made on distinctions above
the "family" level, such as Ceratopsoidea or Ceratopsomorpha, and forms of
ambiguous or non-ceratopsid position, such as *Zuniceratops* or *Avaceratops.*
Fortunately, *Asiaceratops* (=non-diagnostic crap?) is not mentioned.
Cheers,
Jaime A. Headden
Little steps are often the hardest to take. We are too used to making leaps in
the face of adversity, that a simple skip is so hard to do. We should all learn
to walk soft, walk small, see the world around us rather than zoom by it.
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)