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Item A new multi-faceted framework for deciphering Diplodocid ontogeny(Montana State University - Bozeman, College of Letters & Science, 2015) Woodruff, David Cary; Chairperson, Graduate Committee: John R. Horner; Denver W. Fowler and John R. Horner were co-authors of the article, 'A new multi-faceted framework for deciphering Diplodocid ontogeny' which is contained within this thesis.Since sauropod dinosaurs lack the extravagant cranial features that are important to tracking ontogenetic trajectories (changes through growth), sauropods generally garner less focus on development than those dinosaurs with expressive cranial displays. The apparent lack of features that radically change through ontogeny has even led some to speculate that sauropods exhibited isometric growth. Yet within the past decade a small number of morphologic features have been demonstrated to undergo significant morphologic change; thus maturity can be tracked in ways other than histologic analysis (bone microstructure). The recognition of features that change dramatically through ontogeny hints at significant phylogenetic and biomechanical consequences in the immature sauropod condition. However the topic of morphologic ontogenetic change in sauropods is highly debated, with some question as to the validity of these apparent patterns. The current study will attempt to recognize additional morphologic and histologic features that can be used to infer maturity in diplodocid sauropods. By examining a broad range of features that span every aspect of the skeleton, the goal of this analysis is to substantiate previous ontogenetic inferences and conclusions. The findings of this analysis indicate that contrary to previous notions, diplodocid sauropods underwent radical ontogenetic changes in several skeletal elements. This analysis also establishes a suite of morphologic and histologic attributes that in combination can be used as a guide to identify maturational status in other diplodocid specimens. In addition this study also raises question to the validity of small bodied sauropod specimens that were previously recognized as distinct species.Item Initiation of post-diapause development and reinstatement of diapause in Cephus Cinctus Nort.(Montana State University - Bozeman, College of Agriculture, 1953) Church, Norman StanleyItem Studies on the embryonic development and embryonic diapause in Arphia conspersa (Scudd.) and Arphia pseudonietana (Thomas) (Orthoptera, Acrididae) and the effects of plant growth hormones on reproduction and diapause(Montana State University - Bozeman, College of Agriculture, 1982) Jurenka, Russell AllenItem The ecology of selected grasshopper species along an elevational gradient(Montana State University - Bozeman, College of Agriculture, 1995) Wachter, David HarrisonItem A genomic screen for Zic1 target genes in neural development(Montana State University - Bozeman, College of Letters & Science, 2006) Li, Shuzhao; Chairperson, Graduate Committee: Christa Merzdorf; Edward A. Dratz (co-chair)The transcription factor Zic1 plays important roles in patterning the neural plate in early vertebrate development. A crucial step toward understanding the mechanisms of Zic1 function is to identify the downstream target genes. We misexpressed Zic1 in animal caps from Xenopus embryos, and screened for differential gene expression with DNA microarrays. Candidate genes from these microarray data were further validated by quantitative PCR. Through this study, eleven genes have been shown to be directly upregulated by Zic1. One of the direct targets of Zic1 is a novel gene that we have named Xfeb. Xfeb is expressed in the presumptive hindbrain region during neurula stages and in somite tissues later in development. Xfeb represses the hindbrain gene hoxB1 and the anterior neural gene otx2, suggesting that Xfeb is involved in regionalizing the neural plate, possibly by ensuring a posterior expression limit for otx2.