Symposium on Stegosauria Proceedings

[Daniel Marty <daniel.marty@palaeojura.ch>]

Dear All

An international conference on Stegosaur finds of the world was  
organized by the Sauriermuseum Aathal (Switzerland) on 8th & 9th June  
2009, (http://www.sauriermuseum.ch/Dstegosymp.htm) and 8 proceedings  
articles (edited by Jean-Paul Billon-Bruyat & Daniel Marty) are now  
published in the second issue 2010 of the Swiss Journal of  
Geosciences. Articles can be downloaded at: http://www.springerlink.com/content/n3531615224k/

Hereafter, citations and abstracts (without italics and small caps!):

Billon-Bruyat, J.-P. & Marty, D. 2010: Preface: Symposium on  
Stegosauria proceedings
An international conference on stegosaur finds of the world organized  
by the Sauriermuseum Aathal (8th and 9th June 2009, Aathal,  
Switzerland). Swiss Journal of Geosciences, 103/2, 131-141. DOI:  
10.1007/s00015-010-0027-z


Billon-Bruyat, J.-P., Mazin, J.-M., Pouech, J. 2010: A stegosaur tooth  
(Dinosauria, Ornithischia) from the Early Cretaceous of southwestern  
France. Swiss Journal of Geosciences, 103/2, 143-153. DOI: 10.1007/ 
s00015-010-0028-y

"The spotty nature of the terrestrial fossil record for the Mesozoic  
hinders a more complete understanding of dinosaur diversity. For  
stegosaurs (Ornithischia), the plated dinosaurs, only a few and  
fragmentary remains are reported from the Early Cretaceous of Europe.  
A recent revision concluded that only a partial vertebra of the nomen  
dubium Craterosaurus (?Aptian, England) could be considered as  
stegosaurian. Here we report on a stegosaur tooth from the Early  
Cretaceous (Berriasian) Purbeckian deposits of Cherves-de-Cognac  
(Charente), southwestern France. This tiny tooth was examined in  
detail using microtomography. Comparisons being limited by the rarity  
of stegosaur tooth rows material (e.g., from the skull of the holotype  
of Stegosaurus stenops) and dental material, notably from Europe, we  
observed new material of cf. Stegosaurus armatus and Hesperosaurus  
mjosi from the Upper Jurassic Morrison Formation of Wyoming (USA). The  
tooth shows the most similarities to the Late Jurassic  
generaStegosaurus and Hesperosaurus, but differs in having a  
distinctive downwardly arched (V-shaped) cingulum on the ?lingual face  
(maxillary tooth hypothesis). It is referred to as Stegosauria  
indeterminate, a medium-sized quadrupedal herbivore that inhabited an  
emerged land between the Armorican Massif and the Massif Central. This  
finding is the first evidence of a stegosaur from the Early Cretaceous  
of France and a welcome addition to the meagre European record of that  
time. In addition, it is the second stegosaurian tooth crown reported  
from Europe. The assemblage of ornithischians of Cherves-de-Cognac  
shares some similarities with that of the Early Cretaceous  
(Berriasian) of the Purbeck Limestone Group, southern England. The  
relative rarity of ornithischian osteological remains in both  
Purbeckian environments suggests that most of these dinosaurs were  
mainly inhabitants of inland terrestrial palaeoenvironments."


Carpenter, K. 2010: Species concept in North American stegosaurs.  
Swiss Journal of Geosciences, 103/2, 155-162. DOI: 10.1007/ 
s00015-010-0020-6

"The plated thyreophoran or stegosaurian dinosaur Stegosaurus armatus  
was named in 1877 by Marsh for fragmentary remains from the Morrison  
Formation (Upper Jurassic) of Colorado, USA. Subsequent discoveries  
from the same formation in Wyoming and Colorado (USA) have been  
assigned to separate stegosaurian genera and species, but most of  
these are no longer considered valid. More recently, a partial  
stegosaurian skeleton from Wyoming was named Hesperosaurus mjosi.  
However, the validity of this genus has been questioned recently,  
raising the question: how much osteological difference among stegosaur  
taxa is needed to separate genera from species? The question is  
examined vis-à-vis species and genus recognition in other dinosaurs,  
including iguanodonts, lambeosaurine iguanodontids, chasmosaurine  
ceratopsians, tyrannosaurid theropods, and diplodocid sauropods. The  
basis for taxonomic distinction is largely philosophical: if the  
species are morphologically distinct enough, they should be treated as  
separate genera. Based on these criteria, Hesperosaurus mjosi is a  
distinct taxon."



Christiansen, N.A., Tschopp, E. 2010: Exceptional stegosaur integument  
impressions from the Late Jurassic Morrison Formation of Wyoming.  
Swiss Journal of Geosciences, 103/2, 163-171. DOI: 10.1007/ 
s00015-010-0026-0

"Dinosaur skin impressions are rare in the Upper Jurassic Morrison  
Formation, but different sites on the Howe Ranch in Wyoming (USA),  
comprising specimens from diplodocid, camarasaurid, allosaurid and  
stegosaurian dinosaurs, have proven to be a treasure-trove for these  
soft-tissue remains. Here we describe stegosaurian skin impressions  
from North America for the first time, as well as the first case of  
preservation of an impression of the integument that covered the  
dorsal plates of stegosaurian dinosaurs in life. Both have been found  
closely associated with bones of a specimen of the  
stegosaurianHesperosaurus mjosi Carpenter, Miles and Cloward 2001. The  
scales of the skin impression of H. mjosi are very similar in shape  
and arrangement to those of Gigantspinosaurus sichuanensis Ouyang  
1992, the only other stegosaurian dinosaur from which skin impressions  
have been described. Both taxa show a ground pattern of small  
polygonal scales, which in some places is interrupted by larger oval  
tubercles surrounded by the small scales, resulting in rosette-like  
structures. The respective phylogenetic positions of G.sichuanensis as  
a basal stegosaurian and H. mjosi as a derived form suggest that most  
stegosaurians had very similar skin structures, which also match the  
most common textures known in dinosaurs. The integumentary impression  
from the dorsal plate brings new data to the long-lasting debate  
concerning the function of dorsal plates in stegosaurian dinosaurs.  
Unlike usual dinosaur skin impressions, the integument covering the  
dorsal plates does not show any scale-like texture. It is smooth with  
long and parallel, shallow grooves, a structure that is interpreted as  
representing a keratinous covering of the plates. The presence of such  
a keratinous covering has affects on all the existing theories  
concerning the function of stegosaurian plates, including defense,  
thermoregulation, and display, but does not permit to rule out any of  
them."



Farlow, J.O., Hayashi, S., Tattersall, G.J. 2010: Internal vascularity  
of the dermal plates of Stegosaurus (Ornithischia, Thyreophora). Swiss  
Journal of Geosciences, 103/2, 173-185. DOI: 10.1007/s00015-010-0021-5

"X-ray computed tomography and petrographic thin sectioning were used  
to study internal features of the plates of the thyreophoran dinosaur  
Stegosaurus and the osteoderms of Alligator. Infrared thermographic  
imaging of basking caimans was used to examine possible differential  
blood flow to osteoderms and other parts of the skin. Multiple large  
openings in the Stegosaurus plate base lead to a linear, mesiodistally  
oriented vestibule, which in turn apically sends off multiply  
branching “pipes”. The pipes are best developed in the basal half of  
the plate, and communicate with cancellous regions (some of which  
presumably were vascular spaces) throughout the plate interior. Some  
internal vascular features also connect with vascular pits and grooves  
on the plate surface. Alligator osteoderms show a similar internal  
vascularity. In crocodylians, the osteoderms serve as armor and help  
to stiffen the back for terrestrial locomotion, but their vascularity  
enables them to be used as sources of calcium for egg shelling, as  
sites of lactate sequestration, and possibly for heat exchange with  
the external environment, as suggested by our infrared thermographic  
imaging of basking caimans. Thyreophoran osteoderms presumably had  
multiple functions as well. In Stegosaurus the potential  
thermoregulatory role of the plates may have been greater than in  
other thyreophorans, by virtue of their extensive external and  
internal vascularity, their large size, thin cross-sections above the  
plate base, dorsal position, and alternating arrangement."



Galton, P.M. 2010: Species of plated dinosaur Stegosaurus (Morrison  
Formation, Late Jurassic) of western USA: new type species designation  
needed. Swiss Journal of Geosciences, 103/2, 187-198. DOI: 10.1007/ 
s00015-010-0022-4

"Stegosaurus armatus Marsh 1877, based on a partial tail and a very  
large dermal plate from the Morrison Formation (Late Jurassic) of  
Morrison, Wyoming, USA, is a nomen dubium. Valid Morrison stegosaur  
species (with possible autapomorphies, dermal “armor” considered if  
present), with most holotypes consisting of a disarticulated partial  
postcranial skeleton at most, include: Hypsirhophus discurus Cope 1878  
(characters of incomplete vertebrae, a dorsal and a caudal; Garden  
Park near Cañon City, Colorado); Stegosaurus ungulatus Marsh 1879  
(half skeleton with partial skull; three pairs of small flat dermal  
spines adjacent to terminal tail spikes; Quarry 12, Como Bluff near  
Como station, Wyoming; syntype is holotype of S. duplexMarsh 1887,  
half skeleton lacking armor; Quarry 11, Como Bluff); Diracodon  
laticeps Marsh 1881b (just partial dentaries with few teeth, diastema  
between predentary and tooth 1; Quarry 13, Como Bluff); Stegosaurus  
sulcatus Marsh 1887 (pair of ?tail spikes with greatly enlarged base;  
Quarry 13, Como Bluff); S. longispinusGilmore 1914 (characters of  
distal caudal vertebrae, tail spikes: two pairs, sub-equal bases,  
transversely flattened, very elongate; Alcova, Wyoming); and  
Hesperosaurus mjosi Carpenter, Miles & Cloward, 2001 (?Stegosaurus  
mjosi; partial articulated skeleton with skull, no limbs, several  
plesiomorphic and autapomorphic characters, dorsal plates longer than  
tall; Wyoming). However, the well known valid nominal species, S.  
stenops Marsh 1887 (12 autapomorphies, three alternating flat plates  
adjacent to terminal tail spikes; Garden Park), is based on a  
virtually complete articulated skeleton lacking only the terminal  
caudal vertebrae and first pair of tail spikes. It includes 17 dermal  
plates, is still exposed as preserved on the block, and is the current  
basis for Stegosaurus. The International Commission on Zoological  
Nomenclature (ICZN) will be petitioned to designate S. stenops Marsh  
1887 as the new type species of Stegosaurus Marsh 1877 in order to  
conserve Stegosauria Marsh 1877 and Stegosauridae Marsh1880 (also  
Stegosauroidea, Stegosaurinae)."

Maidment, S.C.R. 2010: Stegosauria: A historical review of the body  
fossil record and phylogenetic relationships. Swiss Journal of  
Geosciences, 103/2, 199-210. DOI: 10.1007/s00015-010-0023-3

"The first partial skeleton of a stegosaurian dinosaur was discovered  
in a brick pit in Swindon, UK in 1874. Since then, numerous  
stegosaurian remains have been discovered from Europe, North America,  
Africa and Asia, and continue to be discovered regularly. Stegosaurs  
are known from the Middle Jurassic to the Early Cretaceous; no  
definitive evidence of the clade is known from younger deposits. New  
discoveries are improving our understanding of stegosaur biology and  
showing that stegosaurs were more morphologically diverse than was  
previously realized. A new phylogeny, which includes all valid  
stegosaurian taxa, largely agrees with previous studies and shows the  
European Dacentrurinae was sister taxon to Stegosaurus. Poor  
resolution at the base of Stegosauria is probably due to the  
fragmentary nature of many of the Chinese taxa."

Mallison, H. 2010: CAD assessment of the posture and range of motion  
of Kentrosaurus aethiopicus Hennig 1915. Swiss Journal of Geosciences,  
103/2, 211-233. DOI: 10.1007/s00015-010-0024-2

"A computer aided design analysis using high-resolution laser scans of  
the bones of the stegosaurKentrosaurus aethiopicus Hennig 1915 from  
the Late Jurassic Tendaguru Formation indicates that in the habitual  
walking pose the forelimbs were probably held erect, and that strong  
humeral flexion and abduction mainly occurred in a defensive stance.  
Rapid gaits with unsupported phases could not be used. The neck  
allowed sufficient lateral flexion to guarantee good sight in all  
directions including posteriorly. The tail covered an arch of roughly  
180° and had sufficient range to be used as a weapon. Possibly, the  
animal could accomplish tail blows against specific targets in sight.  
Also, a tripodal pose is suggested to have been possible, roughly  
doubling the maximum vertical feeding height of Kentrosaurus."

Reichel, M. 2010: A model for the bite mechanics in the herbivorous  
dinosaur Stegosaurus (Ornithischia, Stegosauridae). Swiss Journal of  
Geosciences, 103/2, 235-240. DOI: 10.1007/s00015-010-0025-1

"Although the herbivorous dinosaur Stegosaurus (Ornithischia,  
Stegosauridae) is a well-described Late Jurassic taxon, little is  
known about the feeding habits and biomechanics of its homodont  
dentition. The presence of a rhamphotheca has been suggested, but it  
is still unknown how much such structure would have participated in  
the foraging behaviour of Stegosaurus. To better understand the  
feeding mechanism of this taxon, three-dimensional models of a  
Stegosaurus tooth were created, using the software ZBrush®. One model  
was simple and lacked serrations, whereas the other model included  
serrations. Those models were then transferred to the software  
Strand7®, where finite element analyses took place. The models were  
given material properties of enamel, based on studies done with  
crocodilian and mammalian teeth. In addition to that, bite forces were  
calculated for Stegosaurus, based on skull proportions. The results  
show little difference between the force distributions on the serrated  
and non-serrated models, indicating an efficient mechanism of stress  
dissipation that avoids high stresses being transferred to the jaw  
bones during biting. Digital plant models were also created to test  
the calculated bite forces inStegosaurus, which suggests this animal  
was capable of biting through smaller branches. Computer modelling and  
analyses provide additional information about feeding habits and plant  
preferences forStegosaurus, and can be adapted for studying other  
comparable herbivorous taxa."


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