Late Cretaceous Vertebrates from Madagascar: Implications for Gondwanan Biogeography

马达加斯加白垩纪脊椎动物的提取及其对贡德瓦纳生物地理学的意义。作者：A.作者：Catherine A. Forster，Raymond R. Rogers，and Scott D.以前由NSF资助的研究已经确定马达加斯加西北部的Mahajanga盆地拥有一些来自南半球的晚白垩世脊椎动物的最完整和保存最完好的标本。 他们的发现使岛上晚白垩世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，鳄鱼，恐龙，鸟类和哺乳动物的标本。 更广泛地说，参与马哈赞加盆地项目的研究人员已经阐明了几种脊椎动物高等类群的解剖学，古生物学和系统发育关系，记录了盆地的上白垩纪地层学和沉积学，为该岛灭绝和现存脊椎动物动物群的地理起源提供了关键见解，并在中生代期间对冈瓦纳板块构造提出了重要的新见解。 然而，在马哈赞加盆地的广阔的古生物学和地质学未勘探的白垩纪岩石中，还有许多工作要做。 很明显，即使在主要研究区，与世界上其他更彻底研究的地区相比，对脊椎动物多样性的取样仍然不足。 此外，尽管一些分类群的标本质量精美，完整，但绝大多数物种仅以零碎和孤立的标本为代表。 最后，上白垩纪地层的松散性质和高年降雨量确保了新地点和新标本的供应每年都会得到补充。 通过持续的工作，PI相信Mahajanga盆地脊椎动物群将成为白垩纪最好的动物群样本之一，也是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扩大初步努力，在采样仍然不足的主要野外地区发现更多的脊椎动物化石;调查1999年发现的新野外地区;对已经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;进一步阐明地质背景，包括古环境和古气候;以及检验与冈瓦纳大陆断裂有关的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.