The smallest of the largest: a new look at possible dwarfing in sauropod dinosaurs     

Jianu  Coralia-Maria  Weishampel  David B. 《Geologie en Mijnbouw》1999,78(3-4):335-343

Franz Baron Nopcsa recognised that the Late Cretaceous titanosaurid sauropod from Transylvania, Magyarosaurus dacus, was much smaller than the better known sauropods from the Upper Jurassic of the United States and even from Late Cretaceous deposits elsewhere in the world. In keeping with his biogeographic interpretations, Nopcsa viewed this difference as a consequence of body-size effects via island habitation. We present a preliminary re-evaluation of Nopcsa's claims and their heterochronic consequences using two approaches, viz. (1) regression analysis of humeral data as a means of establishing patterns in body size among titanosaurids, and (2) optimisation of humeral data onto titanosaurid cladograms to evaluate evolutionary trends within the clade. Our regression analysis is based on twenty species distributed among fourteen genera of neosauropods and uses length and mid-shaft mediolateral width of the humerus of presumed fully adult forms, and of growth samples that consist of postnatal to adult individuals. Linear regression analysis suggests that, among adult neosauropods, M. dacus appears to be represented by the smallest individuals; that M. dacus humeri appear to be more similar to those of subadults than to adults of other taxa; and that this juvenile morphology may constitute dwarfing in M. dacus by paedomorphosis. In order for these regressions to reflect their evolutionary context more fully, we also present optimisation analyses of humeral form within Titanosauroidea. Although many aspects of the phylogeny of this clade are relatively poorly resolved, preliminary results of our analyses are consistent with the conclusion that M. dacus was a heterochronic dwarf.  相似文献   

Dinosaur remains from the type Maastrichtian: an update     

Weishampel  David B.  Mulder  Eric W.A.  Dortangs  Rudi W.  Jagt  John W.M.  Jianu  Coralia-Maria  Kuypers  Marcel M.M.  Peeters  Hans H.G.  Schulp  Anne S. 《Geologie en Mijnbouw》1999,78(3-4):357-365

Isolated cranial and post-cranial remains of hadrosaurid dinosaurs have been collected from various outcrops in the type area of the Maastrichtian stage during the last few years. In the present contribution, dentary and maxillary teeth are recorded from the area for the first time. Post-cranial elements comprise a newly collected, fragmentary, large right metatarsal III and a broken ?right humerus, recently recognised in the collections of Teylers Museum (Haarlem). Unfortunately, none of these remains can be identified to species level. The available material suggests, however, that more than one taxon of non-lambeosaurine hadrosaurid and a possible euhadrosaurian are represented. Most of the new finds are stratigraphically well documented, which means that they may be linked to the recently published sequence-stratigraphic interpretation of the type Maastrichtian. Dinosaur remains recorded previously from the Maastrichtian type area are tabulated.

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