A redescription and phylogenetic analysis based on new material of the fossil newtsTaricha oligocenicaVan Frank, 1955 andTaricha lindoeiNaylor, 1979 (Amphibia, Salamandridae) from the Oligocene of Oregon

Abstract

Complete body fossils of salamanders are relatively rare, but provide critical information on the evolutionary roots of extant urodele clades. We describe new specimens of the fossil salamandrids Taricha oligocenica Van Frank, 1955, and Taricha lindoei Naylor, 1979, from the Oligocene Mehama and John Day formations of Oregon that illustrate aspects of skeletal morphology previously unseen in these taxa, and contribute to our understanding of population-level variation. Morphological analysis of these specimens supports the classification of T. oligocenica and T. lindoei as two different species, distinct from extant Taricha. Parsimony-based, heuristic analysis of phylogeny using 108 morphological characters for 40 taxa yields different results from a phylogenetic analysis that excludes four taxa known only via vertebrae. Our smaller analysis generally agrees with molecular phylogenies of the family Salamandridae, but with poorer resolution for molgin newts, especially between Taricha and Notophthalmus. The analysis including all taxa produced polytomies mostly related to complications from several fossil taxa. The presence or absence of dorsally expanded, sculptured neural spine tables on trunk vertebrae, an important character in past descriptions of fossil salamandrids, appears to be either homoplastic within the Salamandridae, or requires an expansion of characters or character states. Taricha oligocenica and T. lindoei are separate species of an at least 33 million-year-old clade, but their relationships with each other and extant North American salamandrids remain unclear with current levels of morphological data. Salamandrid research requires additional morphological data, particularly for the vertebrae and ribs, to better resolve salamandrid evolutionary history through morphological characters.

Microtomography of an enigmatic fossil egg clutch from the Oligocene John Day Formation, Oregon, USA, reveals an exquisitely preserved 29-million-year-old fossil grasshopper ootheca

“…The upper Eocene to lower Miocene John Day Formation is subdivided into seven members-Big Basin, Turtle Cove, Kimberly, Haystack Valley, Balm Creek, Johnson Canyon, and Rose Creek-in successive order (Albright et al 2008). Abundant plant fossils are known from the early Oligo cene Bridge Creek flora of the Big Basin Member, but few vertebrate remains are known from it (Samuels et al 2016;Jacisin and Hopkins 2018). In contrast, the overlying Turtle Cove and Kimberly members yield few fossil plants but preserve an exceptional collection of Oligocene fauna (Fremd 2010;Graham 2014).…”