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New Papers on the Roof

Hat-tip to Angela for the title...! Sorry I haven't been posting lately -- the usual mass of other priorities has prevented me from getting to things! Thanks to everyone else for posting lots of stuff in my absence! Here's some noops (uh, that's "new papers") for y'all that I don't think have been mentioned yet:

Upchurch, P., Barrett, P.M., Zhao, X., and Xu, X. 2007. A re-evaluation of Chinshakiangosaurus chunghoensis Ye vide Dong 1992 (Dinosauria, Sauropodomorpha): implications for cranial evolution in basal sauropod dinosaurs. Geological Magazine 144(2):247-262. doi: 10.1017/S0016756806003062.

ABSTRACT: Re-description of the left dentary of Chinshakiangosaurus chunghoensis reveals that it possesses an unusual combination of 'prosauropod' and 'sauropod' character states. Cladistic analysis places Chinshakiangosaurus as one of the most basal sauropods known currently. Mapping of dentary and dental characters onto the most parsimonious topologies yields insights into the sequence of acquisition of a number of feeding-related characters. For example, it seems that basal sauropodomorphs (traditional prosauropod taxa) possessed a fleshy cheek that attached to the mandible along a marked ridge, and that the same structure was present in the most basal sauropods. The early sauropod skull developed a lateral plate that reinforced the bases of the tooth crowns labially, and had wrinkled tooth enamel and a concavity on the mesial portion of the lingual part of each crown, while retaining a fleshy cheek and a relatively weak symphysis. More advanced sauropods (eusauropods) lost the cheek, perhaps in order to increase the gape of the jaws in response to a change in feeding style that involved collection of larger quantities of poor quality foliage.

Taylor, M.P., and Naish, D. 2007. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England. Palaeontology 50(6):1547-1564. doi: 10.1111/j.1475-4983.2007.00728.x.

ABSTRACT: Xenoposeidon proneneukos gen. et sp. nov. is a neosauropod represented by BMNH R2095, a well-preserved partial mid-to-posterior dorsal vertebra from the Berriasian-Valanginian Hastings Beds Group of Ecclesbourne Glen, East Sussex, England. It was briefly described by Lydekker in 1893, but it has subsequently been overlooked. This specimen's concave cotyle, large lateral pneumatic fossae, complex system of bony laminae and camerate internal structure show that it represents a neosauropod dinosaur. However, it differs from all other sauropods in the form of its neural arch, which is taller than the centrum, covers the entire dorsal surface of the centrum, has its posterior margin continuous with that of the cotyle, and slopes forward at 35 degrees relative to the vertical. Also unique is a broad, flat area of featureless bone on the lateral face of the arch; the accessory infraparapophyseal and postzygapophyseal laminae which meet in a V; and the asymmetric neural canal, small and round posteriorly but large and teardrop-shaped anteriorly, bounded by arched supporting laminae. The specimen cannot be referred to any known sauropod genus, and clearly represents a new genus and possibly a new 'family'. Other sauropod remains from the Hastings Beds Group represent basal Titanosauriformes, Titanosauria and Diplodocidae; X. proneneukos may bring to four the number of sauropod 'families' represented in this unit. Sauropods may in general have been much less morphologically conservative than is usually assumed. Since neurocentral fusion is complete in R2095, it is probably from a mature or nearly mature animal. Nevertheless, size comparisons of R2095 with corresponding vertebrae in the Brachiosaurus brancai holotype HMN SII and Diplodocus carnegii holotype CM 84 suggest a rather small sauropod: perhaps 15 m long and 7600 kg in mass if built like a brachiosaurid, or 20 m and 2800 kg if built like a diplodocid.

(Yay, another "X" dinosaur!  Now we need some more "Q"s...)

Barrett, P.M., and Wang, X.-L. 2007. Basal titanosauriform (Dinosauria, Sauropoda) teeth from the Lower Cretaceous Yixian Formation of Liaoning Province, China. Palaeoworld 16(4):265-271. doi: 10.1016/j.palwor.2007.07.001.

ABSTRACT: The Yixian Formation of Liaoning Province, People's Republic of China has yielded a diverse fauna of non-avian dinosaurs, but is dominated by small-bodied taxa. Here, we describe a series of isolated teeth from the Lujiatun Beds of the formation that are referable to a basal titanosauriform sauropod. Some of the teeth possess a distinctive circular boss on the lingual surface, which suggests that they are referable to cf. Euhelopus sp. This identification provides some additional support for biostratigraphical correlations between the Jehol Group and the Mengyin Formation of Shandong Province that suggest an Early Cretaceous age for the latter unit. Moreover, the titanosauriform affinities of the teeth provide further evidence for the dominance of this sauropod clade in eastern Asia during the Cretaceous.

Zhou, C.-F., Gao, K.-Q., Fox, R.C., and Du, X.-K. 2007. Endocranial morphology of psittacosaurs (Dinosauria: Ceratopsia) based on CT scans of new fossils from the Lower Cretaceous, China. Palaeoworld 16(4):285-293. doi: 10.1016/j.palwor.2007.07.002.

ABSTRACT: Psittacosaurs, small basal ceratopsians with a parrot-like beak, are among the most abundant dinosaurs, but occur only in the Early Cretaceous of East Asia. Although the general morphology of psittacosaurs is fairly well understood, the endocranial anatomy of the group has never been described. New discoveries of well-preserved skulls from the celebrated Liaoning beds in northeastern China provide the material for conducting research on psittacosaur endocranial morphology. Using computed tomography scans of three-dimensionally preserved skulls, this study reveals basic endocranial anatomy of psittacosaurs and provides the first palaeoneurological evidence of psittacosaurs in relation to their behaviour. Although commonly believed to have had a small brain and small eyes, psittacosaurs had relatively high brain/body size ratios that are comparable to those in the large theropod Tyrannosaurus, and probably had a keen sense of smell and acute vision, as evidenced by their enlarged olfactory lobes and bulbous optic lobes. The configuration of the semicircular canals agrees with limb proportions to suggest that psittacosaurs were agile animals, perhaps better able to escape predation by carnivorous dinosaurs on that account. The behavioural adaptations implied by this study may have been crucial for the successful radiation of psittacosaurs during the Early Cretaceous of East Asia.

Mayr, G. 2007. Avian higher-level phylogeny: well-supported clades and what we can learn from a phylogenetic analysis of 2954 morphological characters. Journal of Zoological Systematics and Evolutionary Research. doi: 10.1111/j.1439-0469.2007.00433.x. ABSTRACT: It has been shown that increased character sampling betters the accuracy of phylogenetic reconstructions in the case of molecular data. A recently published analysis of avian higher-level phylogenetics based on 2954 morphological characters now provides an empirical example to test whether this is also true in the case of morphological characters. Several clades are discussed which are supported by multiple analyses of mutually independent molecular data (sequences of nuclear genes on different chromosomes and mitochondrial genes) as well as morphological apomorphies, but did not result from parsimony analysis of the large morphological data set. Incorrect character scorings in that analysis notwithstanding, it is concluded that in the case of morphological data, increased character sampling does not necessarily better the accuracy of a phylogenetic reconstruction. Because morphological characters usually have a strongly varying complexity, many simple and homoplastic characters may overrule fewer ones of greater phylogenetic significance in large data sets, thus producing a low ratio of phylogenetic signal to 'noise' in the data.

Kring, D.A. 2007. The Chicxulub impact event and its environmental consequences at the Cretaceous-Tertiary boundary. Palaeogeography, Palaeoclimatology, Palaeoecology 255(1-2):4-21. doi: 10.1016/j.palaeo.2007.02.037.

ABSTRACT: An impact-mass extinction hypothesis for the Cretaceous-Tertiary (K/T) boundary transition has been confirmed with multiple lines of evidence, beginning with the discovery of impact-derived Ir in K/T boundary sediments and culminating in the discovery of the Chicxulub impact crater. Likewise, a link between the Chicxulub impact crater and K/T boundary sediments has been confirmed with multiple lines of evidence, including stratigraphic, petrological, geochemical, and isotopic data. The environmental effects of the Chicxulub impact event were global in their extent, largely because of the interaction of ejected impact debris with the atmosphere. The environmental consequences of the Chicxulub impact event and their association with the K/T boundary mass extinction event indicate that impact cratering processes can affect both the geologic and biologic evolution of our planet.

Prasad, G.V.R., Verma, O., Sahni, A., Parmar, V., and Khosla, A. 2007. A Cretaceous hoofed mammal from India. Science 318:937. doi: 10.1126/science.1149267.

ABSTRACT: The sedimentary record documenting the northward drift of India (Late Cretaceous to late Early Eocene) has recently provided important clues to the evolution, radiation, and dispersal of mammals. Here, we report a definitive Late Cretaceous (Maastrichtian) archaic ungulate (Kharmerungulatum vanvaleni genus et species nova) from the Deccan volcano-sedimentary sequences exposed near Kisalpuri village in Central India. This find has important implications for the origin and diversification of early ungulates and raises three possible paleobiogeographic scenarios: (i) Archaic ungulates may have been cosmopolitan in distribution. (ii) Kharmerungulatum might be an immigrant from Western Asia. (iii) Archaic ungulates may have originated in India.

Cobbett, A., Wilkinson, M., and Wills, M.A. 2007. Fossils impact as hard as living taxa in parsimony analyses of morphology. Systematic Biology 56(5):753-766. doi: 10.1080/10635150701627296.

ABSTRACT: Systematists disagree whether data from fossils should be included in parsimony analyses. In a handful of well-documented cases, the addition of fossil data radically overturns a hypothesis of relationships based on extant taxa alone. Fossils can break up long branches and preserve character combinations closer in time to deep splitting events. However, fossils usually require more interpretation than extant taxa, introducing greater potential for spurious codings. Moreover, because fossils often have more "missing" codings, they are frequently accused of increasing numbers of MPTs, frustrating resolution and reducing support. Despite the controversy, remarkably little is known about the effects of fossils more generally. Here we provide the first systematic study, investigating empirically the behavior of fossil and extant taxa in 45 published morphological data sets. First-order jackknifing is used to determine the effects that each terminal has on inferred relationships, on the number of MPTs, and on CI' and RI as measures of homoplasy. Bootstrap leaf stabilities provide a proxy for the contribution of individual taxa to the branch support in the rest of the tree. There is no significant difference in the impact of fossil versus extant taxa on relationships, numbers of MPTs, and CI' or RI. However, adding individual fossil taxa is more likely to reduce the total branch support of the tree than adding extant taxa. This must be weighed against the superior taxon sampling afforded by including judiciously coded fossils, providing data from otherwise unsampled regions of the tree.We therefore recommend that investigators should include fossils, in the absence of compelling and case specific reasons for their exclusion.

Xing, L., Wang, F., Pan, S., and Chen, W. 2007. The discovery of dinosaur footprints from the Middle Cretaceous Jiaguan Formation of Qijiang County, Chongqing City. Acta Geologica Sinica 81(11):1591-1602.

(Thanks to Kazuo Takahashi for that last one!)

The "official" versions of these papers, mentioned some time ago when they came out as on-line first, are now also available:

Senter, P. 2007. A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda). Journal of Systematic Palaeontology 5(4):429-463. doi: 10.1017/S1477201907002143.

ABSTRACT: The most comprehensive phylogenetic analysis of the theropod clade Coelurosauria to date, is presented here, with 85 coelurosaurian ingroups and 360 characters, using Allosaurus and Sinraptor as outgroups. The strict consensus tree is highly resolved and has the following topology: Tyrannosauroidea + (Compsognathidae + (Arctometatarsalia + (Ornitholestes + (Therizinosauroidea + (Alvarezsauridae + (Oviraptorosauria + (Avialae + (Troodontidae + Dromaeosauridae)))))))). The analysis places Coelurus and Tanycolagreus at the base of Tyrannosauroidea, Deinocheirus within Arctometatarsalia, Protarchaeopteryx within Oviraptorosauria and Epidendrosaurus at the base of Avialae. The analysis results in wide phylogenetic separation between Caenagnathus (close to the base of Oviraptorosauria) and Chirostenotes (placed within a clade of crested oviraptorids), casting doubt on their synonymy. All taxa with an enlarged, trenchant ungual on the second toe are placed within Troodontidae or Dromaeosauridae; at the base of the latter is an unenlagiine clade that includes Unenlagia and Rahonavis. The hypothesis that dromaeosaurids are secondarily flightless birds is not supported.

Hone, D.W.E., and Benton, M.J. 2007. An evaluation of the phylogenetic relationships of the pterosaurs among archosauromorph reptiles. Journal of Systematic Palaeontology 5(4):465-469. doi: 10.1017/S1477201907002064.

ABSTRACT: The phylogenetic position of pterosaurs among the diapsids has long been a contentious issue. Some recent phylogenetic analyses have deepened the controversy by drawing the pterosaurs down the diapsid tree from their generally recognised position as the sister group of the dinosauromorphs, to lie close to the base of Archosauria or to be the sister group of the protorosaurs. Critical evaluation of the analyses that produced these results suggests that the orthodox position retains far greater support and no close link can be established between pterosaurs and protorosaurs.

Difley, R. 2007. Biostratigraphy of the North Horn Formation at North Horn Mountain, Emery County, Utah; pp. 439-454 in Willis, G.C., Hylland, M.D., Clark, D.L., and Chidsey, T.C., Jr. (eds.), Central Utah - Diverse Geology of a Dynamic Landscape. Utah Geological Association Publication 36. Utah Geological Association, Salt Lake City.

ABSTRACT: A general biostratigraphic chart of the North Horn Formation type locality synthesizes a suite of published and new faunal and stratigraphic information. Vertebrate bone, eggshell and track bed data, as well as invertebrate, plant, microfossil and trace fossils, are plotted against time to reveal patterns of stratigraphic fossil diversity and possible fossil co-occurrences, and to allow paleoenvironmental interpretations. It illustrates that much supporting data concerning paleoenvironments and paleoclimate can be derived from invertebrates, microfossils, plants and trace fossils. When systematically placed in a stratigraphic arrangement, all fossils from small fossil fragments to spectacular specimens such as Alamosaurus and Tyrannosaurus rex are together useful for reconstructing the North Horn ecosystem of central Utah. New macrofossil and pollen data better define the K-T transition than was previously possible. Some of the stratigraphy is updated from previous reports. North Horn Mountain is overall the most paleontologically useful area of the Cretaceous part of the North Horn Formation of the central Wasatch Plateau.

Scheetz, R.D., and Britt, B.B. 2007. Paleontological discoveries of James A. 'Dinosaur Jim' Jensen in central Utah; pp. 455-465 in Willis, G.C., Hylland, M.D., Clark, D.L., and Chidsey, T.C., Jr. (eds.), Central Utah - Diverse Geology of a Dynamic Landscape. Utah Geological Association Publication 36. Utah Geological Association, Salt Lake City.

ABSTRACT: James A. ("Dinosaur Jim") Jensen's paleontological career was a dynamic chapter in Utah's vertebrate paleontologic history in the 1960s through the 1970s. Much of his success stemmed from the local contacts he made with people familiar with the Utah backcountry, and his charismatic public persona. As a result, he built one of the more active paleontological field programs in the country for his time, collecting major fossil troves from central Utah, including the "world's smallest dinosaur" and the first relatively complete dinosaur egg in North America.
This is a historical summary of Jim Jensen's fossil discoveries in central Utah presented to illustrate the paleontological diversity of the region. The importance of some of these finds, especially from the Triassic Chinle Formation, has yet to be fully realized. Discoveries in the Upper Jurassic Morrison and Lower Cretaceous Cedar Mountain Formations provided the first look at some important aspects of known dinosaurs. His work in the North Horn Formation aided students of mammals and lower vertebrates and helped preserve the dinosaur record of the Late Cretaceous. His investigation of the Paleocene Flagstaff Formation and Eocene Green River Formation resulted in the recovery of exceptionally preserved champsosaurs, fish, and trace fossils. And, even though Pleistocene fossils were not his forte, he cultivated relationships with others who routinely reported Ice Age fossils to him, resulting in the recovery of spectacular specimens. As scientifically valuable as these findings are, each discovery also had a human side, including both problems and successes, some of which are just coming to light.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Jerry D. Harris Director of Paleontology Dixie State College Science Building 225 South 700 East St. George, UT 84770 USA Phone: (435) 652-7758 Fax: (435) 656-4022 E-mail: jharris@dixie.edu and dinogami@gmail.com http://cactus.dixie.edu/jharris/


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