Sigilmassasaurus brevicollis is an enigmatic theropod dinosaur from the early Late Cretaceous (Cenomanian) of Morocco, originally based on a few isolated cervical vertebrae. Ever since its original description, both its taxonomic validity and systematic affinities were contentious. Originally considered to represent its own family, Sigilmassasauridae, the genus has variously been suggested to represent a carcharodontosaurid, an ornithischian, and, more recently, a spinosaurid. Here we describe new remains referrable to this taxon and re-evaluate its taxonomic status and systematic affinities. Based on the new remains, a re-evaluation of the original materials, and comparisons with other spinosaurids, the holotype of Sigilmassasaurus brevicollis is identified as an anterior dorsal, rather than a cervical vertebra, and differences between elements referred to this taxon can be explained by different positions of the elements in question within the vertebral column. Many characters used previously to diagnose the genus and species are found to be more widespread among basal tetanurans, and specifically spinosaurids. However, the taxon shows several autapomorphies that support its validity, including the presence of a strongly rugose, ventrally offset triangular platform that is confluent with a ventral keel anteriorly in the mid-cervical vertebral centra and a strongly reduced lateral neural arch lamination, with no or an incomplete distinction between anterior and posterior centrodiapophyseal laminae in the posterior cervical and anterior dorsal vertebrae. We argue furthermore that Spinosaurus maroccanus, also described on the basis of isolated cervical vertebrae from the same stratigraphic unit and in the same paper as Sigilmassasaurus brevicollis, is a subjective synonym of the latter. Both a detailed comparison of this taxon with other theropods and a formal phylogenetic analysis support spinosaurid affintities for Sigilmassasaurus. However, we reject the recently proposed synonymy of both Spinosaurus maroccanus and Sigilmassasurus brevicollis with Spinosaurus aegyptiacus from the Cenomanian of Egypt, as there are clear differences between the vertebrae of these taxa, and they do not share any derived character that is not found in other spinosaurids. Together with a comparison with other spinosaurid vertebral material from the Kem Kem, this suggests that more than one taxon of spinosaurid was present in the Kem Kem assemblage of Morocco, so the referral of non-overlapping material from this unit to a single taxon should be regarded with caution.

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The original hypodigm of the controversial mid-Cretaceous Moroccan dinosaur Sigilmassasaurus brevicollis is redescribed, and the diagnosis of the taxon is revised. Unambiguously referred material is restricted to cervical and anterior dorsal vertebrae sharing apomorphies with the holotype. A newly recognized diagnostic character of Sigilmassasaurus is the absence of anterior and posterior interzygapophyseal laminae of the neural arch, so that the neural spine directly meets the dorsal margin of the neural canal. A phylogenetic analysis supports the inclusion of Sigilmassasaurus in Tetanurae but not in Carcharodontosauridae. Sigilmassasaurus is distinct from all other theropods known from comparable material and is thus retained as a valid taxon.

Positional variation is documented in ornithomimid pedal unguals from the Dinosaur Park and Horseshoe Canyon Formations of Alberta, Canada, and characters for identifying the position of isolated ornithomimid pedal unguals are discussed. Ungual morphology has been used recently to argue for the coexistence of two distinct ornithomimosaurs, a basal taxon and distinctly more derived taxon, in the Early Cretaceous Arundel Clay of Maryland, USA. However, these conclusions are based on misconceptions of the morphology and positional variability of ornithomimosaur unguals. Some characters previously cited as diagnostic of ornithomimosaur unguals are not actually observed in this clade, or are more homoplastically distributed among theropods. Other characters proposed to distinguish between the two pedal ungual morphs in the Arundel Clay material are shown in the Albertan ornithomimid material to consistently distinguish the different ungual positions within the pes of one individual. Claims of multiple distinct ornithomimosaur taxa in the Arundel Clay are premature, as the two pedal ungual morphotypes more likely represent positional variation in a single taxon.

Sloboda for keeping my project in mind during their prospecting trips that recovered several potential new records of Ornithomimidae from southern Alberta. For assistance during collection visits I thank Carl Mehling and Mark Norell at the American Museum of Natural History; Margaret Currie, Jordan Mallon, and Kieran Shepherd at the

We describe a new partial skull with braincase of a maiasaurin hadrosaurid from the Milk River Ridge Reservoir near Warner, southern Alberta, as the first diagnostic occurrence of Maiasaura in Canada. This material was collected in the Oldman Formation, at approximately the same stratigraphic level as a nearby bonebed of the ceratopsid Coronosaurus brinkmani. The assignment of this specimen to Maiasaura, rather than to Brachylophosaurus, is supported by the narrow and acute posterior margin of the external naris, the relationship between the postorbital and squamosal in the supratemporal bar, and the morphology of the frontals, which are greatly thickened and elevated anteriorly, with the dorsal surface not completely covered by the nasofrontal contact at adult size. The occurrence of both Maiasaura and Brachylophosaurus in approximately similar-aged deposits of the Comrey Sandstone zone in southern Alberta provides support for some cladogenesis in the evolutionary history of Maiasaurini. Geographically, the more western distribution of Maiasaura localities with respect to all Brachylophosaurus localities is consistent with the hypothesis that a preference for more inland versus seaway-adjacent habitats may have influenced the phylogenetic divergence of these taxa.

Five new partial skulls of the hadrosaurid dinosaur Maiasaura peeblesorum from the Linster Quarry bone bed (Two Medicine Formation, Campanian) in Montana, USA, provide the basis for a description of the skull roof and braincase morphology of this taxon. These skulls additionally form an ontogenetic series consisting of one subadult, two small "intermediate adults", and two larger "mature adults". The subadult skull is approximately two thirds as wide as the largest adult and lacks a nasofrontal crest, suggesting that the crest formed relatively late in ontogeny compared to some other hadrosaurids. As in closely related taxa, larger skulls of M. peeblesorum have a proportionately wider braincase and a larger, more rugosely ridged nasofrontal contact for supporting a larger crest. In the two largest adults, the skull roof incipiently overhangs the anterior margin of the dorsotemporal fenestrae. In the largest skull examined, the crest is semicircular in anterior view and incorporates flared, anteriorly concave prefrontals in its lateral margins. Intraspecific variation in M. peeblesorum is observed in cranial characters previously discussed as interspecific variation in related taxa, including the prominence of dorsal depressions on the frontal, and the position of the foramen for the facial nerve (CN VII). Although cranial ontogeny in Maiasaura shares some trends with Brachylophosaurus and Probrachylophosaurus, it deviates in other ways from the previous heterochronic model proposed for the evolution of Maiasaurini.

Ornithomimid material from the Belly River Group (Campanian) of Alberta, Canada is described as sharing characters with Qiupalong henanensis from the Qiupa Formation of Henan Province, China. Derived characters and character combinations of the pubis and astragalocalcaneum were previously used to diagnose Q. henanensis and support the referral of this material to Qiupalong sp., representing the first known occurrences of Qiupalong outside of China. Qiupalong is the sixth ornithomimid taxon to be reported from the Dinosaur Park Formation and the first ornithomimid genus with a transcontinental distribution. The Alberta material represents the oldest known occurrences of Qiupalong, and a reconsideration of character evidence suggests that this genus is phylogenetically nested within other North American ornithomimids. A North American origin for Qiupalong and subsequent dispersal to Asia is proposed.