More Papers from the Early Sauropodmorph Volume

["Jerry D. Harris" <jharris@dixie.edu>]

These in addition to the one I mentioned earlier; there are still others in 
the volume I haven't seen yet...

Upchurch, P., Barrett, P.M., and Galton, P.M. 2007. A phylogenetic analysis 
of basal sauropodomorph relationships: implications for the origin of 
sauropod dinosaurs; pp. 57-90 in Barrett, P.M. and Batten, D.J. (eds.), 
Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs. Special 
Papers in Palaeontology 77. Palaeontological Association, London.

ABSTRACT: New discoveries, revision of existing taxa and the application of 
cladistic analysis have all shed light on the relationships of basal 
sauropodomorphs. Nevertheless, the interrelationships proposed in recent 
studies have varied widely, with some authors advocating the view that 
Prosauropoda and Sauropoda are monophyletic sister-taxa, whereas others 
favour an extreme form of prosauropod paraphyly with respect to sauropods. A 
data set comprising 292 characters for seven outgroups and 27 ingroup 
sauropodomorph taxa is presented and analysed. The most parsimonious trees 
suggest that Efraasia, Mussaurus, Thecodontosaurus and Saturnalia are 
increasingly more distant sister-taxa to the remaining sauropodomorphs. The 
latter are divided into two monophyletic sister-groups: a plateosaurian 
clade containing Plateosaurus, Lufengosaurus, Massospondylus, Coloradisaurus 
and others, and a sauropod clade, which includes melanorosaurs (near its 
base), Antetonitrus, Chinshakiangosaurus, Vulcanodon, Barapasaurus and 
eusauropods. Bootstrap values and constrained analyses with Templeton's 
tests indicate that support for many of the proposed relationships is 
relatively weak. This results from the inclusion of poorly known taxa, such 
as Blikanasaurus, and from considerable levels of character conflict. 
Character mapping indicates several apomorphic features that support the 
monophyly of a plateosaurian clade or subgroups within it. In addition, it 
appears that approximately 20 apomorphies are acquired early in basal 
sauropodomorph evolution, but are reversed to the plesiomorphic state in 
basal sauropods and eusauropods. Aside from their impact on phylogenetic 
uncertainty, these reversals may reflect important aspects of early sauropod 
evolution that relate to shifts in the ecological niches occupied by these 
taxa.


Barrett, P.M., and Upchurch, P. 2007. The evolution of feeding mechanisms in 
early sauropodomorph dinosaurs; pp. 91-112 in Barrett, P.M. and Batten, D.J. 
(eds.), Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs. 
Special Papers in Palaeontology 77. Palaeontological Association, London.

ABSTRACT: Sauropodomorph dinosaurs were the dominant terrestrial herbivores 
of the Late Triassic to Late Jurassic, but the early evolution of herbivory 
is poorly documented in this clade. In particular, the transition from the 
relatively simple feeding mechanisms of basal sauropodomorphs and 
prosauropods to the more complex feeding apparatus of sauropods has received 
little attention, owing largely to the paucity of basal sauropod material. 
Discoveries of Late Triassic and Early Jurassic sauropods and 
reinterpretation of sauropodomorph phylogeny have alleviated this problem, 
revealing new information on the sequence of character acquisitions that 
occurred during the origin of sauropods. The evolution of sauropod herbivory 
was intimately associated with concurrent trends towards increased body size 
and quadrupedal locomotion. Recognition of Jingshanosaurus and 
Melanorosaurus as basal sauropods closes
the morphological gap that existed between more advanced sauropods, such as 
Vulcanodon, and prosauropods.


Bonnan, M.F., and Yates, A.M. 2007. A new description of the forelimb of the 
basal sauropodomorph Melanorosaurus: implications for the evolution of 
pronation, manus shape and quadrupedalism in sauropod dinosaurs; pp. 157-168 
in Barrett, P.M. and Batten, D.J. (eds.), Evolution and Palaeobiology of 
Early Sauropodomorph Dinosaurs. Special Papers in Palaeontology 77. 
Palaeontological Association, London.

ABSTRACT: The evolution of a quadrupedal limb posture is characteristic of 
the earliest sauropod dinosaurs and involved secondarily modifying a 
non-supporting forelimb into a pronated support column with a semicircular 
metacarpus. Melanorosaurus readi is a basal sauropodomorph phylogenetically 
close to the earliest sauropods, and the morphology of its forelimb sheds 
additional light on the origins of the unique manus shape of sauropods and 
the initial stages of manus pronation. We describe the osteology of a 
complete forelimb of Melanorosaurus (NM QR3314), as well as partial referred 
specimens (SAM-PK-K3449, SAM-PKK3532), and show that the forelimb elements 
of this taxon comprise a mosaic of basal sauropodomorph and basal sauropod 
characteristics. The humerus retains the plesiomorphic morphology of basal 
sauropodomorphs. However, like sauropods, the forearm of Melanorosaurus 
clearly shows the development of a proximal craniolateral process on its 
ulna and a shift in the position of the radius to a more cranial orientation 
relative to the ulna. The manus of Melanorosaurus was not a semicircular 
colonnade as in sauropods: instead its metacarpals were arranged closer to 
the orientation more typical of theropods and basal sauropodomorphs. A 
recurved, medially divergent pollex claw and straighter but blunter claws on 
digits II and III were present. We suggest that the characteristic U-shaped 
manus of eusauropods and neosauropods may have resulted from mosaic 
evolution. The forelimb morphology of Melanorosaurus suggests that pronation 
of the manus occurred early in basal sauropods through a change in 
antebrachial morphology, but that changes to the morphology of the manus 
followed later in eusauropods, perhaps related to further manus pronation 
and improved stress absorption in the metacarpus. Thus, we conclude that 
changes to antebrachial morphology and manus morphology were not temporally 
linked in sauropods and constitute separate phylogenetic events.


Wedel, M. 2007. What pneumaticity tells us about 'prosauropods', and vice 
versa; pp. 207-222 in Barrett, P.M. and Batten, D.J. (eds.), Evolution and 
Palaeobiology of Early Sauropodomorph Dinosaurs. Special Papers in 
Palaeontology 77. Palaeontological Association, London.

ABSTRACT: Pneumatic (air-filled) bones are an important feature of the 
postcranial skeleton in pterosaurs, theropods and sauropods. However, there 
is no unambiguous evidence for postcranial pneumaticity in basal 
sauropodomorphs and even the ambiguous evidence is scant. Patterns of 
skeletal pneumatization in early sauropods and theropods suggest that basal 
saurischians had cervical air sacs like those of birds. Furthermore, 
patterns of pneumaticity in most pterosaurs, theropods and sauropods are 
diagnostic for abdominal air sacs. The air sacs necessary for flow-through 
lung ventilation like that of birds may have evolved once (at the base of 
Ornithodira), twice (independently in pterosaurs and saurischians) or three 
times (independently in pterosaurs, theropods and sauropods). Skeletal 
pneumaticity appears to be more evolutionarily malleable than the air sacs 
and diverticula that produce it. The evolution of air sacs probably 
pre-dated the appearance of skeletal pneumaticity in ornithodirans.


Pol, D., and Powell, J.E. 2007. New information on Lessemsaurus sauropoides 
(Dinosauria: Sauropodomorpha) from the Upper Triassic of Argentina; pp. 
223-243 in Barrett, P.M. and Batten, D.J. (eds.), Evolution and 
Palaeobiology of Early Sauropodomorph Dinosaurs. Special Papers in 
Palaeontology 77. Palaeontological Association, London.

ABSTRACT: Postcranial remains of Lessemsaurus sauropoides are described 
herein, including elements of the vertebral column, pectoral girdle, 
forelimb, pelvis and hindlimb. These remains were closely associated with 
the cervicodorsal neural arches previously described from this taxon. This 
assemblage of bones shows numerous derived characters, including some 
derived similarities exclusively shared with Antetonitrus ingenipes from the 
Upper Triassic of South Africa. Additionally, this material reveals an 
unusual combination of plesiomorphic character states present in many 
non-eusauropod sauropodomorphs together with derived characters that suggest 
affinities with eusauropods and related taxa.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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)