Worldwide distribution of the modiomorphid bivalve genus Caspiconcha in late Mesozoic hydrocarbon seeps
Worldwide distribution of the modiomorphid bivalve genus Caspiconcha in late Mesozoic hydrocarbon seeps
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DOI：
10.4202/app.2011.0026
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发表时间：
2013-06-01
影响因子：
1.8
通讯作者：
Campbell, Kathleen A.
中科院分区：
文献类型：
--
作者：
Jenkins, Robert G.;Kaim, Andrzej;Campbell, Kathleen A.
保存极为完好的双壳软体动物莫迪奥拉的标本是从加利福尼亚州北部的下白垩统(Barremian)碳氢化合物渗漏沉积物中采集的。该标本与M.main的模式系列以及加利福尼亚上侏罗统至下白垩统渗漏地区的其他各种标本一起被重新描述，并被称为碳氢化合物渗漏受限的变形体属Caspiccha。我们还包括了对Myoconcha americana的描述，因为以前的一些报告错误地将Myoconcha americana与Caspiccha main同义。此外，我们还报道了Caspiccha sp.从日本北海道早白垩世(阿尔比亚期)碳氢化合物渗漏中发现，并综述了目前所描述的Caspiconcha的所有种，以及可能属于该属的其他种。结果表明，在晚侏罗世至早白垩世油气渗漏中，Caspconcha分布广泛，但此后稀少，最后一次出现在日本上白垩统。这种宏观进化模式类似于在渗漏受限腕足类中观察到的模式。在早白垩世末Caspiccha的衰落和最后一次出现在坎帕尼亚纪后，表层动物群-半动物群渗漏特有双壳类的生态位基本上是空白的，直到始新世才重新占据，出现了泡囊类和深海修饰素双壳类。Memor的正式归入Caspiccha属，将渗漏时的Myilds化石记录限制在后中生代，因此，根据分子数据估计的化学合成Mytilds化石记录与它们的分歧年龄之间的差异较小。
Exceptionally well preserved specimens of the bivalve mollusc Modiola major were collected from a Lower Cretaceous (Barremian) hydrocarbon seep deposit in northern California. This material, together with the type series of M. major, and various other specimens from Upper Jurassic to Lower Cretaceous seep localities in California, is redescribed and referred to the hydrocarbon seep-restricted modiomorphid genus Caspiconcha. We include also a description of Myoconcha americana because some previous reports have incorrectly synonymized Myoconcha americana with Caspiconcha major. In addition, we report Caspiconcha sp. from a Lower Cretaceous (Albian) hydrocarbon seep from Hokkaido, Japan, and we review all currently described species of Caspiconcha, and other species that probably belong to this genus. We demonstrate that Caspiconcha had a widespread distribution in Late Jurassic to Early Cretaceous hydrocarbon seeps, but became rare thereafter, with the last representative occurring in Upper Cretaceous strata of Japan. This macroevolutionary pattern is similar to that observed in the seep-restricted brachiopods. After the decline of Caspiconcha at the end of the Early Cretaceous and its last occurrence in the Campanian, the ecological niche of epifaunal to semi-infaunal seep endemic bivalves was largely vacant and not reoccupied until the Eocene with the appearance of the vesicomyid and bathymodiolin bivalves. The formal placement of M. major into the genus Caspiconcha restricts the fossil record of mytilids at seeps to post-Mesozoic times, and thus there is less discrepancy between the fossil record of chemosynthetic mytilids and their divergence age estimates from molecular data.