Description and phylogenetic implications of extant and fossil oologic remains
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2004
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Abstract
Rigorous analytical techniques are combined with phylogeneticsystematic methodology to provide a new perspective on the scientific informativeness of the eggs and eggshells of both extant and extinct dinosaurs. Re-description of the eggs of paleognathous birds reveals that numerous eggshell characteristics were overlooked by previous investigators. A cladistic analysis of discrete egg characters of paleognaths reveals that although trees based on egg data provide less resolution among taxa than those based on skeletal data, egg data do provide phylogenetic information and can help resolve disagreements in relationships derived from skeletal data. In an analysis based on the egg data alone, tinamous are basal among paleognaths, Apteryx is basal among ratites and the sister taxon of an unresolved clade consisting of large ratites, within which Aepyornis and dinornithids form a subclade and Casuarius and Dromaius form a subclade. When the egg data are combined with the skeletal data of Bledsoe (1988), the clade of Apteryx, Casuarius, and Dromaius is dissolved, and Apteryx moves to a basal position within Ratitae. Analysis of 13 absolute measurements and ratios from the eggs reveals that only 4 of these continuous characters are suitable for cladistic analysis. A cladistic analysis of the continuous and discrete characters provides further resolution among taxa within the tree based on egg data in that Struthio and Rhea form a clade. Fossil eggs of several dinosaurs (including birds) are described and included in a cladistic analysis of 24 ootaxa, the results of which, in general, are comparable to those drawn from skeletal-based studies. Sauropod eggs are basal in Saurischia, allosauroid eggs are basal in Theropoda, the eggs of oviraptorids and dromaeosaurids form a derived clade, and the eggs of troodontids and birds form a clade. Unexpected results include the basal position of therizinosaurid eggs, a clade consisting of Protoceratopsidovum (Protoceratops eggs) and troodontid eggs, and a clade consisting of Deinonychus and oviraptorid eggs. These anomalies may call the alleged parentage of these eggs into question. The evolutionary-systematic method that was used to construct the traditional parataxonomic system for fossil eggs is eschewed, and a new nomenclatural system employing a phylogenetic-systematic methodology is proposed. Phylogenetic definitions are erected for seven ooclades of Saurischia, following the tenets of phylogenetic nomenclature.
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Bibliography: p. 234-251
Some pages are in colour.
Some pages are in colour.
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Citation
Zelenitsky, D. K. (2004). Description and phylogenetic implications of extant and fossil oologic remains (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/12586