Palaeoecology of a primate-friendly, middle Eocene community from Laredo, Texas and a review of stratigraphic occurrences of Paleogene land mammals across the Gulf Coastal Plain, USA

摘要

Recent analysis of primate remains in the Casa Blanca local fauna from the late middle Eocene Laredo Formation at Laredo, Texas has shown that the fauna’s primate species diversity was greater than previously reported. Recognition of Mahgarita cf. M. stevensi provided the first record of an Old World cercomoniine species in a Uintan community in North America. The presence of three omomyids indicates that primate species diversity in the paralic Casa Blanca community was similar to that in late Uintan age faunas in both Trans-Pecos, Texas and in the Uinta Basin of Utah. Palaeoecologic evidence from associated plant, invertebrate and vertebrate remains indicates that the regional community setting was a tropical mangrove swamp fringing a lowland coastal rain forest. This late middle Eocene climate was probably similar to the early middle Eocene climate which prevailed in Germany at the time the Messel community inhabited the region. A review of stratigraphic occurrences of Paleogene land mammal remains across the Gulf Coastal Plain indicates that the Casa Blanca fauna is one of only two Paleogene land mammal communities known from Gulf Coastal deposits. These coastal land mammal occurrences provide rare opportunities to correlate Paleogene land mammal communities known from the interior of North America with strata bearing marine species.