New paper on Silesaurus (and no, I don't have a pdf, but would like one...)

["Thomas R. Holtz, Jr." <tholtz@umd.edu>]

Bone Histology of the Late Triassic Dinosauriform Silesaurus opolensis
Fostowicz-Frelik, L., and T. Sulej. 2009. Bone histology of Silesaurus 
opolensis Dzik, 2003 from the Late Triassic of Poland. Lethaia. 
10.1111/j.1502-3931.2009.00179.x

Abstract- The phylogenetic relationships of Silesaurus opolensis have been the 
subject of intense debate since its discovery. Silesaurus possesses some 
features characteristic of ornithischian dinosaurs, such as the presence of a 
beak at the front of the lower jaw, yet it lacks a number of important femoral 
and dental synapomorphies of Dinosauria. The microstructure of the long bones 
(femur, tibia and metatarsal) and ribs of this species reveals a relatively 
intensive rate of growth, comparable with that seen in small dinosaurs and the 
gracile crocodylomorph Terrestrisuchus. Cortical bone formed mainly by 
periosteal tissue with fibro-lamellar matrix (in older specimens parallel 
fibred) shows very little secondary remodelling and only in one specimen (large 
tibia ZPAL Ab III â 1885) few lines of arrested growth are present in the 
outermost cortex. The vascularization is relatively dense, mainly longitudinal 
and ceases towards the periphery, forming almost avascular parallel fibred bone 
at the bone surface.. This indicates maturation and significant decrease in the 
growth ratio in mature specimens of S. opolensis. The delicate trabeculae 
exhibit cores formed by the primary cancellous tissue lined with lamellar 
endosteal bone. The rather intense growth of S. opolensis implies a relatively 
high metabolic rate. Moreover, evidence from the fibro-lamellar tissue, 
predominant in the cortex, suggests that this kind of rapid bone deposition 
could be more typical of Archosauria than previously assumed, a prerequisite 
for the evolution of the very fast growth rates observed in large 
ornithischians, sauropods and large theropods. 

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA