概括
阿根廷晚期三级哺乳动物床的精细约会揭示了南美和北美动物交换的新时间表. 确定了关键的界限,包括公类和类动物抵达南美洲的时间.
科学领域:
- 古生物学的古生物学
- 地质时间学 (Geochronology)
- 在平流体学上,平流体学是平流体学.
背景情况:
- 阿根廷卡塔马卡省的晚期三级哺乳动物产床为动物进化和迁徙提供了关键的见解.
- 之前对这些床的年龄估计缺乏精确性,阻碍了南美和北美动物事件的准确相关性.
研究的目的:
- 通过阿根廷的Chapadmalalan床对Chasicoan的年龄估计进行细化.
- 确定关键动物事件和陆地桥梁形成的精确时间边界.
- 为了调查北美和南美之间动物交换的时间.
主要方法:
- 图夫的放射性同位素 (-) 测年.
- 晚期三级哺乳动物带沉积物序列的磁石层学.
主要成果:
- 建立了关键的平流学边界的新年龄估计:查西科安-胡艾奎尔 (9.0万年),胡艾奎尔-蒙特赫莫桑 (5.0万年) 和蒙特赫莫桑-查帕德马拉兰 (3.0万年).
- 记录了第一个南美出现的 procyonids (北美起源) 低于6.0万年前的单位.
- 记录了南美最初的虫动物 (Sigmodontini部落) 在Montehermosan年龄的床上.
- 确定了地 (南美起源) 在9.5和9.0万年前之间最早的北美到来.
- 证实了巴拿马陆地桥梁在3.0亿年前建立,通过晚期布兰肯/查帕德马拉兰时期促进了显著的动物交换.
结论:
- 这种精细的时分层结构为了解南美新生哺乳动物动物动态提供了一个强大的框架.
- 这项研究澄清了关键生物地理事件的时间,包括北美哺乳动物向南美洲和相反的分散.
- 这些数据强调了巴拿马陆地桥在促进晚期三级生物交换方面发挥的关键作用.
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