Late Cretaceous Vertebrates from Madagascar: Implications for Gondwanan Biogeography

来自马达加斯加的晚白垩世脊椎动物：对冈瓦南生物地理学的意义david W. Krause, Gregory A. Buckley, Catherine A. Forster, Raymond R. Rogers和Scott D. sampsonar - 0106477pis之前由美国国家科学基金会资助的研究已经确定，马达加斯加西北部的Mahajanga盆地拥有南半球最完整、保存最完好的晚白垩世脊椎动物标本。他们的发现使岛上晚白垩纪脊椎动物的物种多样性增加了五倍，现在包括鱼类、青蛙、海龟、蛇、鳄形动物、恐龙、鸟类和哺乳动物的标本。更广泛地说，参与Mahajanga盆地项目的研究人员阐明了几个脊椎动物高级分类群的解剖学、古生物学和系统发育关系，记录了该盆地的上白垩纪地层学和沉积学，为岛上灭绝和现存脊椎动物群的生物地理起源提供了关键见解，并为中生代冈瓦南板块构造提供了重要的新见解。然而，在Mahajanga盆地的白垩纪岩石中，在古生物学和地质学上尚未勘探的广阔区域，还有许多工作要做。很明显，即使是在主要的研究区域，与世界上其他更彻底的研究区域相比，脊椎动物多样性的采样仍然不足。此外，尽管某些分类群的标本质量优良、完整，但绝大多数物种的标本都是零碎的、孤立的。最后，上白垩纪地层的松散性质和高年降雨量确保了每年新地点和新标本的供应。随着工作的继续，pi相信Mahajanga盆地的脊椎动物动物群将成为白垩纪时代最好的动物样本之一，并成为与其他冈瓦纳动物群进行比较的主要标准之一。目前建议的主要目标是通过在仍然取样不足的原始野外地区发现更多脊椎动物化石来扩大初步努力；1999年新发现油田调查；对已发现但尚未研究或仅部分研究的标本进行解剖、功能和系统发育分析；地质背景的补充说明，包括古环境和古气候；以及检验与冈瓦纳大陆分裂有关的生物地理学和板块构造假说。

ABSTRACTLATE CRETACEOUS VERTEBRATES FROM MADAGASCAR:IMPLICATIONS FOR GONDWANAN BIOGEOGRAPHYDavid W. Krause, Gregory A. Buckley, Catherine A. Forster, Raymond R. Rogers, and Scott D. SampsonEAR-0106477PIs previous NSF-funded research has established the Mahajanga Basin of NW Madagascar as having some of the most complete and spectacularly preserved specimens of Late Cretaceous vertebrates from the southern hemisphere. Their discoveries have quintupled the previously known species diversity of Late Cretaceous vertebrates from the island and now include specimens of fishes, frogs, turtles, snakes, crocodyliforms, dinosaurs, birds, and mammals. More broadly, investigators involved in the Mahajanga Basin Project have elucidated the anatomy, paleobiology, and phylogenetic relationships of several vertebrate higher taxa, documented the Upper Cretaceous stratigraphy and sedimentology of the basin, provided key insights into the biogeographic origins of both the extinct and extant vertebrate faunas of the island, and shed significant new light on Gondwanan plate tectonics during the Mesozoic. Much remains to be done, however, in the vast expanses of paleontologically and geologically unexplored Cretaceous rocks of the Mahajanga Basin. It is clear that, even in the primary study area, the diversity of vertebrates remains inadequately sampled when compared to more thoroughly studied areas elsewhere in the world. Furthermore, despite the exquisite quality and completeness of the specimens of some taxa, the vast majority of species are represented by only fragmentary and isolated specimens. Finally, the unconsolidated nature of the Upper Cretaceous strata and the high annual rainfall ensures that the supply of new localities and new specimens is replenished on an annual basis. With continued work, the PIs are confident that the Mahajanga Basin vertebrate fauna will become one of the best sampled faunas of Cretaceous age and one of the primary standards against which other Gondwanan faunas are compared. The primary goals of the current proposal are to expand preliminary efforts through additional discoveries of fossil vertebrates in the still under-sampled primary field area; investigation of new field areas discovered in 1999; anatomical, functional, and phylogenetic analysis of specimens already discovered but still unstudied or only partly studied; additional elucidation of geologic context, including paleoenvironment and paleoclimate; and testing of biogeographic and plate tectonic hypotheses related to the breakup of Gondwana.