Abstract Part of a paleo-forest comprised of eight in situ permineralized tree stumps is preserved in the Javelina Formation (middle Maastrichtian, c. 69 Ma) near Alamo Creek in western Big Bend National Park. The stumps are rooted in an immature organic-rich paleosol resembling a modernday Aquept, developed in a landscape depression subject to gleization with a shallow fluctuating groundwater table. Seven of the stumps pertain to the dicotyledonous angiosperm Metcalfeoxylon, and one is a cuppressoid/podocarpoid conifer, indicating that is part of a mixed conifer-dicot forest. The site exhibits a woodland architecture, with stands of closely spaced trees separated on average by 10 m, and open gaps over 100 m in between. Trunk diameters vary from 33 to 97 cm, with estimated crown heights from 23 to 48 m, and represent trees of varied ages in a mature forest. Irregular growth rings are developed in the conifer wood, but absent in the Metcalfeoxylon woods. The local climate may have had one or more annual dry seasons, and the conifers were either more susceptible to moisture stress, or genetically predisposed to express growth rings more markedly than the contemporaneous dicots. Metcalfeoxylon is also the dominant tree type at another paleo-forest preserved near McKinney Spring in the underlying Aguja Formation (late Campanian, c. 75 Ma). Metcalfeoxylon may have grown preferentially in low-lying riparian environments subject to flooding and burial by alluvial overbank deposits, thus favorable to preservation of the stumps in situ. A deficiency of precipitation, along perhaps with browsing pressure exerted by dinosaur herbivores, may have been responsible for maintaining the open woodland physiognomy evident at both sites.

中文翻译：

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美国德克萨斯州大弯国家公园 Javelina 组（上白垩纪）中的被子植物林地

摘要 在大弯国家公园西部阿拉莫溪附近的 Javelina 组（马斯特里赫特中部，约 69 Ma）中保存了由 8 个原位渗透矿化树桩组成的古森林的一部分。这些树桩植根于类似于现代 Aquept 的未成熟的富含有机物的古土壤中，在景观洼地中发育，受到浅层波动地下水位的影响。其中七个树桩属于双子叶被子植物 Metcalfeoxylon，一个是杯状/罗汉果针叶树，表明它是针叶树-双子叶植物混交林的一部分。该场地展示了一种林地建筑，树木间距平均为 10 m，之间的空隙超过 100 m。树干直径从 33 到 97 cm 不等，估计树冠高度从 23 到 48 m，并代表成熟森林中不同年龄的树木。在针叶木中发育不规则的年轮，但在 Metcalfeoxylon 木中不存在。当地气候可能有一个或多个一年一度的旱季，针叶树要么更容易受到水分胁迫，要么在遗传上比同时期的双子叶植物更容易表达年轮。Metcalfeoxylon 也是保存在 McKinney Spring 附近下伏 Aguja 组（晚坎帕阶，约 75 Ma）的另一个古森林中的主要树种。Metcalfeoxylon 可能优先生长在受洪水淹没的低洼河岸环境中，并被冲积层沉积物掩埋，因此有利于原位保存树桩。降水不足，也许还有恐龙食草动物施加的浏览压力，