See more from this Division: Topical Sessions
See more from this Session: After the Last Ammonite and before the First Horse: Patterns of Ecological and Climatic Change during the Paleocene
Abstract:
Previous work correlating vertebrate fossil localities within the Paleocene Nacimiento Formation across the southern San Juan Basin resulted in the construction of a biostratigraphic framework and the recognition of eight mammal biostratigraphic zones. Recently, intensive collecting of selected vertebrate fossil horizons has greatly enhanced this record. This has at least partly addressed previous collecting biases. Significantly, the pattern of early Paleocene mammal succession in the San Juan Basin is not one of smoothly increasing diversity, but instead is marked by several distinct turnover events. The boundary between the two Puercan biostratigraphic zones, within subchron 29n, is marked by the disappearance of numerous taxa, but also by the appearance of probable immigrants. The Puercan Torrejonian boundary interval, within subchron 28r, remains relatively poorly constrained. However, it is marked by the greatest faunal change observed within the entire sequence. Within the Torrejonian interval, the most significant faunal change is found approximately coincident with the base of subchron 27n. It is marked by the disappearance of several long-ranging mammal taxa, but is accompanied by few appearances. The overall pattern of mammal succession within the Nacimiento Formation suggests a number of different factors influenced mammal composition and diversity during the early Paleocene.
See more from this Division: Topical Sessions
See more from this Session: After the Last Ammonite and before the First Horse: Patterns of Ecological and Climatic Change during the Paleocene