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[dinosaur] Stegoceras novomexicanum validity + dinosaur footprints from New Mexico + marginocephalian combat

Ben Creisler

Some recent (and not so recent) dinosaur papers:

(Many thanks to Vahe Demirjian for bringing the first two to my attention.)

Steven E. Jasinski and Robert M. Sullivan (2016)
The validity of the Late Cretaceous pachycephalosaurid Stegoceras novomexicanum (Dinosauria: Pachycephalosauridae).
In Sullivan, R.M. and Lucas, S.G., eds., 2016, Fossil Record 5. New Mexico Museum of Natural History and Science Bulletin 74: 107-115

In light of a recent paper, we review, and reassess, the validity of the pachycephalosaurid dinosaur Stegoceras novomexicanum (Dinosauria: Ornithischia: Pachycephalosauridae). Specimens that are referred to Stegoceras novomexicanum are all late Campanian (early Kirtlandian) in age and are not only from a restricted stratigraphic horizon at the Fruitland/Kirtland transition, but also from a small geographic area of the San Juan Basin, New Mexico. While some of the characters initially used in diagnosing this taxon may be representative of an earlier (sub-adult) ontogenetic stage, such as the reduction of the size of the posteromedial extension of the parietal and the size of the supratemporal fenestrae, several other characters confirm its validity. These include the shape of the posteromedial extension of the parietal, the relative position of the supratemporal fenestrae, the shape and degree of inflation of the nasal boss, morphology of the prefrontal-frontal suture, curvature of the frontal-parietal suture, and its relative overall size and gracile form relative to the type (lectotype) of Stegoceras validum from the Judithian of Alberta, Canada. Although the holotype of Stegoceras novomexicanum may represent a sub-adult individual, it also possesses some diagnostic features that are indicative of an adult. This combination of features may indicate heterochrony for Stegoceras novomexicanum within the Pachycephalosauridae. Recently recovered small-bodied, high-domed pachycephalosaurid specimens from the Fruitland-Kirtland transition further support our interpretation that this taxon represents a distinct, small-bodied adult pachycephalosaurid in New Mexico. The previously described paratypes, and newly collected specimens, are conservatively assigned to cf. Stegoceras novomexicanum, as all this material comes from a very restricted stratigraphic interval and geographic area.  


Spencer G. Lucas, Sebastian G. Dalman and Robert M. Sullivan (2016)
Cretaceous dinosaur footprints from Sierra County, New Mexico.
In Sullivan, R.M. and Lucas, S.G., eds., 2016, Fossil Record 5. New Mexico Museum of Natural History and Science Bulletin 74: 151-152

Two dinosaur trackways are present in the Upper Cretaceous (Santonian?) Crevasse Canyon Formation near Elephant Butte Reservoir in Sierra County. One is clearly ornithopod, but the other is too poorly preserved to be confidently assigned to a track maker. These are the first dinosaur tracks discovered in Sierra County and suggest more tracks may be found in the Crevasse Canyon Formation.


Also, a paper from last year that has not been mentioned on the DML:

Joseph E. Peterson (2015)
Evolution of marginocephalian combat and patterns of pathology distribution. 
68th Annual Field Conference Guidebook: Cretaceous Conference: Evolution and Revolution
2013 Wyoming Geological Association Guidebook: 141-149

Marginocephalia (Ornithischia: Cerapoda) is a clade of ornithischian dinosaurs that includes Ceratopsia and Pachycephalosauria. This clade is predominantly characterized by a prominent parietosquamosal shelf extending posteriorly over the occiput in the form of a large frill in ceratopsians and a thickened frontoparietal dome in pachycephalosaurs. The function of the respective parietosquamosal shelves has been the subject of much debate in paleontological discussions. Common hypotheses of parietosquamosal shelf function include defense structures in ceratopsians, “battering-rams” in pachycephalosaurids, and display structures for both clades. However, the high variability of ornamentation in both groups suggests similar variability in display functions and combative styles. To trace the potential functions of marginocephalians ornamentation, a collection of 62 pachycephalosaur frontoparietal domes and 45 ceratopsian skeletons from taxa throughout the marginocephalian phylogeny was surveyed for pathologies to assess the frequency and distribution of injuries. Preliminary results show a strong correlation between unique ornamentation morphologies and distributions of frequent injuries. These results suggest that a suit of combative behaviors exists in marginocephalians, comparable to those observed in extant bovids with highly variable cranial horns and ornamentation, as well as likely serving as effective sexual selection structures.