Acridinae

Duellman, William E., Marion, Angela B. & Hedges, Blair, 2016, Phylogenetics, classification, and biogeography of the treefrogs (Amphibia: Anura: Arboranae), Zootaxa 4104 (1), pp. 1-109 : 57-58

Acridinae

The acridines split from the hylines in the late Eocene, 35.6 (32.8–38.4) Mya, followed by radiation in North America beginning in the early Oligocene 30.3 (26.1–34.5) Mya. Thus, there was a second invasion of North America from South America by arboranans. Interestingly, there are no living relatives of North American acridines in Middle America. This North American lineage diverged into two clades in the early Miocene, 30.3 (26.1–34.5) Mya. One of these clades lost a pair of chromosomes to have a complement of 2n = 22 and became the semiaquatic Acris . The timing is consistent with the Lower Miocene fossil, Proacris ( Holman, 1961) .

The second clade of terrestrial frogs includes Pseudacris , which began to radiate (crown node) in the early Miocene, 22.5 (19.6–25.5) Mya. The uplift of the Rocky Mountains and Sierra Nevada Range with the intervening arid Great Basin in the mid-Miocene resulted in vicariance of the Pseudacris clade. A closely-related clade west of the mountains, Hyliola, began to radiate by mid-late Miocene, 11.8 (8.0–15.6) Mya.