Anthracotheres are generalised artiodactyls that have an extensive record in the Cenozoic of Eurasia and Africa. In North America they have been collected in middle Eocene to early Miocene localities from the California Coast, the Great Plains and the Gulf Coast of the United States, with a single record from the early Miocene of Panama. Here we report few specimens from the early Oligocene (Ar1) Iniyoo Local Fauna of north-western Oaxaca, and the earliest Miocene of Simojovel de Allende, in northern Chiapas. This material has diverse features that indicate they belonged to the bothriodontine Arretotherium, such as selenodont cristids associated with the protoconid and hypoconid, the absence of a premetacristid, and the crenulated enamel. They share with Arretotherium acridens and Arretotherium meridionale the absence of a mesiolingual metacristid, but their general morphology and size indicate a close relationship to Ar. meridionale. Nevertheless, in absence of better-preserved specimens, we decided not to assign the fossil material to this species. Specimens from Oaxaca and Chiapas are the first records of anthracotheres in Mexico. These new records link the previous ones from temperate North America and tropical Central America and indicate that Anthracotheriidae had a very wide geographical distribution in North America during the Palaeogene and the Neogene. Additionally, they represent the southern-most records of Arretotherium in North America during the Oligocene and the early Miocene.

A new flower preserved in amber in sediments of Simojovel de Allende, México, is identified as an extinct member of Staphyleaceae, a family of angiosperms consisting of only three genera (Staphylea, Turpinia and Euscaphis), which has a large and abundant fossil record and is today distributed over the Northern Hemisphere. Staphylea ochoterenae sp. nov. is the first record of a flower for this group, which is small, pedicelled, pentamer, bisexual, with sepals and petals with similar size, dorsifixed anthers and superior ovary. Furthermore, the presence of stamens with pubescent filaments allows close comparison with extant flowers of Staphylea bulmada and S. forresti, species currently growing in Asia. However, their different number of style (one vs. three) and the apparent lack of a floral disc distinguish them from S. ochoterenae. The presence of Staphyleaceae in southern Mexico ca. 23 to 15My ago is evidence of the long history of integration of vegetation in low-latitude North America, in which some lineages, such as Staphylea, could move southwards from high latitudes of the Northern Hemisphere, as part of the Boreotropical Flora. In Mexico it grew in association with tropical elements, as suggested by the fossil record of the area.