[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

The Papers That Ate Cincinnati



If you get that reference, you're probably a bigger Dr. Demento fan than me...!

First up, a paper that is likely to spark all sorts of discussion on-list:

Taylor, M.P. 2007. Phylogenetic definitions in the pre-PhyloCode era; implications for naming clades under the PhyloCode. PaleoBios 27(1):1-6.

ABSTRACT: The last twenty years of work on phylogenetic nomenclature have given rise to many names and definitions that are now considered suboptimal. In formulating permanent definitions under the PhyloCode when it is implemented, it will be necessary to evaluate the corpus of existing names and make judgements about which to establish and which to discard. This is not straightforward, because early definitions are often inexplicit and ambiguous, generally do not meet the requirements of the PhyloCode, and in some cases may not be easily recognizable as phylogenetic definitions at all. Recognition of synonyms is also complicated by the use of different kinds of specifiers (species, specimens, clades, genera, suprageneric rank-based names, and vernacular names) and by definitions whose content changes under different phylogenetic hypotheses. In light of these difficulties, five principles are suggested to guide the interpretation of pre-PhyloCode clade-names and to inform the process of naming clades under the PhyloCode: (1) do not recognize "accidental" definitions; (2) malformed definitions should be interpreted according to the intention of the author when and where this is obvious; (3) apomorphy-based and other definitions must be recognized as well as node-based and stem-based definitions; (4) definitions using any kind of specifier taxon should be recognized; and (5) priority of synonyms and homonyms should guide but not prescribe. Strict priority should not be observed in the pre-PhyloCode era, and should not determine which existing names are permanently established; precedence should begin only with the formal establishment of the PhyloCode.

This one is available free at: http://www.miketaylor.org.uk/dino/pubs/taylor2007/Taylor2007-pre-phylocode-pn.pdf. This is one of those kinds of papers that I'll probably have to read a few times to get the overall gist of -- the discussion behind various phylogenetic nomenclatures is, for whatever reason, one of those things that doesn't go into my skull easily -- but it lays out some very good guidelines, at least by my reading. How (or if) they'll ever be implemented, though, remains to be seen, especially for various really contentious definitions (e.g., Aves vs. Avialae, Ornithuromorpha vs. Euornithes) -- after all, it's _people_ dealing with all this rather than strictly logic-based machines (I wonder how the Borg would handle phylogenetic nomenclature...), and emotions have clearly infected some of these debates. One aspect the paper doesn't really cover (though it covers a LOT in its brief 6 pages!), at least not explicitly, is _commonness_ of usage as a criterion, and in particular how a term is most commonly perceived/implemented, which I think is an exceedingly important, if not overarching, component of naming (e.g., Aves has included _Archaeopteryx_ for over 100 years, and even the general public, when they know of _Archaeopteryx_ at all, understands that it is a "bird" -- the paper does discuss vernacular terms), which even though it was not originally constructed to include it (_Archaeopteryx_ being unknown to Linnaeus), to me automatically overrides Avialae and Aves sensu Gauthier; similarly, I've seen Euornithes sensu Sereno used rarely, but Ornithuromorpha, despite its jumbled history, commonly used for the clade of all birds closer to Neornithes (or _Passer domesticus_ if you want a species anchor) than to Enantiornithes (or _Sinornis santensis_), and that oughta count. It's not a perfect argument, I admit -- if it were implemented in its entirety, then _Brontosaurus_ would have priority over _Apatosaurus_ (and frankly, I don't have a huge problem with that) just because of common usage, but of course it's arguable whether or not the most widely understood (e.g., including the non-scientific public) usage of the term _Brontosaurus_ really describes a species (or genus) as opposed to a synonym for "sauropod."


Anyway, enough blithering on my part; on to more papers! This batch includes new papers of a more geological bent:


Roberts, E.M. 2007. Facies architecture and depositional environments of the Upper Cretaceous Kaiparowits Formation, southern Utah. Sedimentary Geology 197(3-4):207-233. doi: 10.1016/j.sedgeo.2006.10.001.

ABSTRACT: The Kaiparowits Formation is an unusually thick package of Upper Cretaceous (late Campanian) strata exposed in Grand Staircase-Escalante National Monument of southern Utah, USA. The formation was deposited within the rapidly subsiding Cordilleran foreland basin as part of a thick clastic wedge derived from sources in the Sevier orogenic belt, thrust sheets in southeastern Nevada and southern California, and the Mogollon slope in southwestern Arizona. Channel systems in the Kaiparowits Formation shifted from northeastward to southeastward flow over time, and for a short period of time, sea level rise in the Western Interior Seaway resulted in tidally influenced rivers and/or estuarine systems. Thick floodbasin pond deposits, large suspended-load channels, and poorly developed, hydromorphic paleosols dominate the sedimentary record, and all are suggestive of a relatively wet, subhumid alluvial system. This is supported by extremely rapid sediment accumulation rates (41 cm/ka), and high diversity and abundance of aquatic vertebrate and invertebrate fossils.


Roca, X., and Nadon, G.G. 2007. Tectonic control on the sequence stratigraphy of nonmarine retroarc foreland basin fills: insights from the Upper Jurassic of central Utah, U.S.A. Journal of Sedimentary Research 77(3):239-255. doi: 10.2110/jsr.2007.021.


ABSTRACT: Continental successions of the North American Western Interior retroarc foreland basin provide an excellent opportunity to evaluate the tectonic controls on nonmarine sequence stratigraphy. The transition between the Upper Jurassic Brushy Basin Member anastomosed fluvial system of the Morrison Formation and the gravelly braided-river deposits of the Buckhorn Conglomerate has been studied to assess the dispersal of coarse clastics and the development of associated basin-wide unconformities in a sequence stratigraphic framework. The sharp contact between the two members is interpreted to be conformable based on stratigraphic, sedimentologic, and petrologic data collected at and near Cedar Mountain in central Utah, while a regional, mature paleosol at the top of the Buckhorn Conglomerate indicates the presence of a major sequence boundary. These interpretations are combined with paleoflow data and fluvial architectural analysis to reconstruct the evolution of the alluvial equilibrium profiles that controlled deposition of the succession.
The Buckhorn Conglomerate is interpreted as an example of a post-orogenic deposit on the basis of (1) its tabular geometry, (2) distance from the contemporaneous thrust belt, (3) shift to transverse paleoflow direction from the preceding Brushy Basin axial drainage, (4) conformable lower contact, and (5) presence of an overlying sequence boundary with a westward-expanding hiatus eroding the coeval foredeep. The onset of a protracted period of low rate of orthogonal convergence between the Farallon and North American Plates resulted in tectonic quiescence and consequent isostatic rebound of the Middle to Late Jurassic thrust belt and the contiguous contemporaneous foredeep, as well as dynamic uplift. The ensuing basin-wide decrease in subsidence rate induced the progradation of the Buckhorn alluvial plain into the Morrison back-bulge depozone, and the subsequent generation of the overlying pedogenic unconformity, which separates the deposits of the Jurassic flexural event from the overlying Sevier tectonostratigraphic unit.


(Haven't read this one myself yet, but from what I understand, it ignores a huge volume of work done in this same area since around 1992...)

Finally, a new, short dinosaur paper and a Mesozoic croc paper, the former from the same issue of _Neues Jahrbuch_ that contains the "underwear dragon" _Pantydraco_ (oh, please...you KNOW that's how it's gonna go down in history...!):

Wings, O., Pfretzschner, H.-U., and Maisch, M.W. 2007. The first evidence of a stegosaur (Dinosauria, Ornithischia) from the Jurassic of Xinjiang/China. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 243(1):113-118.

ABSTRACT: A well preserved dorsal vertebra of a stegosaur is described from the Oxfordian Qigu Formation of the Junggar Basin, northwestern China. This is the first evidence for thyreophoran dinosaurs in this Formation. Previously, stegosaurs have only been recorded from the Lower Cretaceous Tugulu Group of this region. Although the generic identity of the specimen is indeterminate, the find provides confirmation for the presence of stegosaurs in the Jurassic of the Xinjiang Uygur Autonomous Region.


Ösi, A., Clark, J.M., and Weishampel, D.B. 2007. First report on a new basal eusuchian crocodyliform with multicusped teeth from the Upper Cretaceous (Santonian) of Hungary. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 243(2):169-177.


(erects the new taxon _Iharkutosuchus makadii_, a basal eusuchian that is the sister taxon of _Hylaeochampsa_)


...and a pterosaur paper:

Hone, D.W.E., and Benton, M.J. 2007. Cope's Rule in the Pterosauria, and differing perceptions of Cope's Rule at different taxonomic levels. Journal of Evolutionary Biology 20(3):1164-1170. doi: 10.1111/j.1420-9101.2006.01284.x.

ABSTRACT: The remarkable extinct flying reptiles, the pterosaurs, show increasing body size over 100 million years of the Late Jurassic and Cretaceous, and this seems to be a rare example of a driven trend to large size (Cope's Rule). The size increases continue throughout the long time span, and small forms disappear as larger pterosaurs evolve. Mean wingspan increases through time. Examining for Cope's Rule at a variety of taxonomic levels reveals varying trends within the Pterosauria as a whole, as pterodactyloid pterosaurs increase in size at all levels of examination, but rhamphorhynchoid pterosaurs show both size increase and size decrease in different analyses. These results suggest that analyses testing for Cope's Rule at a single taxonomic level may give misleading results.

In this paper, beware that the suppementary information file at the journal's web site appears to be corrupt and unreadable; I've got a good copy if you want it, though.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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/
"Trying to estimate the divergence times
of fungal, algal or prokaryotic groups on
the basis of a partial reptilian fossil and
protein sequences from mice and humans
is like trying to decipher Demotic Egyptian with
the help of an odometer and the Oxford
English Dictionary."
-- D. Graur & W. Martin (_Trends
in Genetics_ 20[2], 2004)