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1
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Hadrosaurs as ungulate parallels: lost life styles and deficient data

100%
Carrano M. T., Janis C. M.
Acta Palaeontologica Polonica
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1999
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tom 44
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nr 3
237-261
Hadrosaur dinosaurs (Ornithischia: Hadrosauridae) were abundant in Late Cretaceous terrestrial environments of North America and Asia. Their derived dental and postcranial specializations for herbivory have led to the suggestion that these dinosaurs were analogous to modern ungulates in lifestyle. Ungulates display a suite of morphological features that are correlated with diet, habitat preference, and sexual dimorphism. In this paper we examine several of these same features in hadrosaurs in order to determine whether they display similar patterns under multivariate analysis. Initial results confirm the resemblances between hadrosaurs and ungulates but suggest that missing data may considerably affect the outcomes of statistical analyses. Using the hadrosaur dataset as a template, we artificially degrade the (previously complete) ungulate datasets and perform the same analyses. Results are consistent with earlier results and provide an opportunity to assess the impact of missing data on the original multivariate structure. Our results support the hypothesis that hadrosaurs were similar to ungulates in patterns of ecomorphology.
2
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The phylogenetic position of the ornithischian dinosaur Stenopelix valdensis from the Lower Cretaceous of Germany and the early fossil record of Pachycephalosauria

100%
Butler R. J., Sullivan R. M.
Acta Palaeontologica Polonica
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2009
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tom 54
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nr 1
21-34
The holotype of Stenopelix valdensis is the most completely known dinosaur specimen from the “Wealden” (Lower Cretaceous) of northwestern Germany, but its phylogenetic position has remained highly controversial. Most recent authors have suggested affinities with the ornithischian clade Marginocephalia, and most commonly to the marginocephalian subclade Pachycephalosauria. A pachycephalosaurian identity would make Stenopelix the only confirmed pre−Late Cretaceous member of this clade, breaking up an extensive ghost lineage which extends to the inferred origin of Pachycephalosauria in the Middle–Late Jurassic. Based upon re−examination of the holotype we here review the characters that have previously been used to assign Stenopelix to either Pachycephalosauria or Ceratopsia. All of these characters are problematic, being based upon inaccurate anatomical interpretations, or having more widespread distributions within Ornithischia than previously realised. We conclude that although the overall anatomy of Stenopelix is consistent with marginocephalian affinities, there is insufficient evidence to support referral to either Pachycephalosauria or Ceratopsia; we consider Stenopelix ?Marginocephalia. A brief review indicates that there is no compelling fossil evidence for pachycephalosaurs prior to the Late Cretaceous.
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Evidence for a sauropod-like metacarpal configuration in stegosaurian dinosaur

100%
Senter P.
Acta Palaeontologica Polonica
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2010
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tom 55
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nr 3
427-432
The stegosaurian forelimb is usually portrayed with the metacarpals slanted and distally spread. However, manual manipulation of stegosaurian metacarpals reveals that in that configuration they do not articulate with each other nor with the rest of the forelimb. Rather, they do articulate with each other and with the rest of the forelimb when posed vertically and arranged in a compact, semi−tubular configuration, as in sauropods. This configuration agrees with data from articulated specimens and trackways. As with sauropods, this metacarpal configuration makes retention of phalanges awkward for locomotion and may be functionally related to the vestigiality of the manual phalanges of the outer digits.
4
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A new ankylosaurid from the Late Cretaceous Two Medicine Formation of Montana, USA

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Penkalski P.
Acta Palaeontologica Polonica
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2014
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tom 59
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nr 3
Oohkotokia horneri gen. et sp. nov. is described based on a specimen in the collections of the Museum of the Rockies, Montana, USA. Oohkotokia exhibits a unique combination of characters not seen in other late Campanian North American ankylosaurids: prominent, horn-like, trihedral squamosal bosses, a small, undistinguished median nasal plate on the dorsal surface of the rostrum, a relatively small occipital condyle, a smooth, finely pitted osteoderm external texture, and triangular lateral osteoderms. Other specimens from the Two Medicine Formation are referable to Oohkotokia. O. horneri, Euoplocephalus tutus, Dyoplosaurus acutosquameus, and Scolosaurus cutleri separate stratigraphically.
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New psittacosaurid highlights skull enlargement in horned dinosaurs

100%
Sereno P. C., Xijin Z., Brown L., Lin T.
Acta Palaeontologica Polonica
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2007
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tom 52
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nr 2
A new psittacosaurid is based on a nearly complete articulated skeleton from northeastern China that differs principally in skull size as compared to the most common and widespread species, Psittacosaurus mongoliensis. The skull of Psittacosaurus majorsp. nov., is 25% larger despite very similar postcranial skeletal dimensions. Such selective skull enlargement is very unusual. Skull size in ceratopsians, in general, scales with positive allometry relative to body mass: species of greater mass have proportionately larger skulls. This pattern stands in marked contrast to that for other vertebrate herbivores, in which larger−bodied species either have proportionately similar or smaller skulls relative to body mass. Larger−bodied ceratopsians evolved skulls that are 50% or more of trunk length—as measured without their expansive cranial frill. Although contemporaneous duck−billed dinosaurs also exhibit some positive allometry in the skull, skull length remains approximately 35% of trunk length. The evolution of extraordinary absolute and relative skull size among ceratopsians appears to have been driven by sexual selection and involved the tandem evolution of reduced head mobility and an obligate quadrupedal posture.
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Osteology and relationships of Olorotitan arharensis, a hollow−crested hadrosaurid dinosaur from the latest Cretaceous of Far Eastern Russia

88%
Godefroit P., Bolotsky Y. L., Bolotsky I. Y.
Acta Palaeontologica Polonica
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2012
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tom 57
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nr 3
The holotype of Olorotitan arharensis from the Maastrichtian Udurchukan Formation in Kundur, Far Eastern Russia, is the most complete dinosaur discovered in Russia and one of the best preserved lambeosaurines outside western North America. This taxon is diagnosed by following autapomorphies: large helmet−like hollow crest higher than the rest of the skull and extending caudally well beyond the level of the occiput; very high postorbital process of jugal (ratio height of postorbital process/length of jugal = 1); rostral portion of the jugal shorter than in other lambeosaurines, with a perfectly straight rostral margin; very asymmetrical maxilla in lateral view, with ventral margin distinctly downturned; very elongated neck composed of 18 cervical vertebrae; tibia as high as the femur; shorter cnemial crest, about one fifth of tibia length. A phylogenetic analysis, based on 118 cranial, dental, and postcranial characters, indicates that Olorotitan is a member of the Corythosaurini clade, and is the sister taxon of Corythosaurus casuarius, Hypacrosaurus stebingeri, and Hypacrosaurus altispinus. The high diversity and mosaic distribution of Maastrichtian hadrosaurid faunas in the Amur−Heilongjiang region are the result of a complex palaeogeographical history and imply that many independent hadrosaurid lineages dispersed readily between western America and eastern Asia at the end of the Cretaceous.
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