Nicholas J. Czaplewski

A New Box Turtle from the Miocene/Pliocene Boundary (Latest Hemphillian) of Oklahoma and A Refined Chronology of Box Turtle Diversification

Abstract A near complete shell from the Hemphillian 4 (Miocene/Pliocene boundary) Buis Ranch local fauna of Beaver County, Oklahoma, represents a fossil box turtle. An anterior contact of neural III and neural V with costal III and costal V only, respectively, presence of a small contact between the suprapygal and eleventh peripherals, development of a thin peripheral lip for articulation with the posterior plastral lobe, placement of the vertebral III/IV sulcus on neural VII, presence of two anterior musk duct glands, a rounded posterior plastral lobe, an elongate shell outline, and a complete neural series diagnose the fossil as a new species, Terrapene parornata n. sp. A phylogenetic analysis of fossil box turtles places T. parornata along the phylogenetic stem of the extant taxon T. ornata. The holotype of ‘Terrapene longinsulae’ cannot be distinguished from Terrapene ornata and is therefore synonymized. Finally, ‘Terrapene’ corneri lacks characters of crown group Terrapene and may therefore represent a stem box turtle. The provenance of the holotype of ‘Terrapene longinsulae’ is more poorly known than previously recognized and this specimen may originate from Kansas or Nebraska and be early Miocene to late Pleistocene in age. Terrapene parornata is therefore the oldest demonstrable representative of crown group Terrapene (ca. 5.3–4.6 Ma). ‘Terrapene’ corneri from the late Barstovian of Nebraska and fragmentary material from the middle Barstovian of Nebraska by contrast are the oldest representative of the Terrapene lineage (ca. 14.5–11.5 Ma). A review of morphological characters related to shell kinesis reveals that most are highly correlated. The results of the phylogenetic analysis converge upon those of molecular data when these correlated characters are omitted from the analysis.

Middle Miocene carnivorans from the Monarch Mill Formation, Nevada

The lowest part of the Monarch Mill Formation in the Middlegate basin, west-central Nevada, has yielded a middle Miocene (Barstovian Land Mammal Age) vertebrate assemblage, the Eastgate local fauna. Paleobotanical evidence from nearby, nearly contemporaneous fossil leaf assemblages indicates that the Middle Miocene vegetation in the area was mixed coniferous and hardwood forest and chaparral-sclerophyllous shrubland, and suggests that the area had been uplifted to 2700–2800 m paleoaltitude before dropping later to near its present elevation of 1600 m. Thus, the local fauna provides a rare glimpse at a medium- to high-altitude vertebrate community in the intermountain western interior of North America. The local fauna includes the remains of fish, amphibians, reptiles, birds, and 25 families of mammals. Carnivorans, the focus of this study, include six taxa (three of which are new) belonging to four families. Canidae are represented by the borophagine Tomarctus brevirostris and the canine Leptocyon sp. indet. The earliest record and second North American occurrence of the simocyonine ailurid Actiocyon is represented by A. parverratis sp. nov. Two new mustelids, Brevimalictis chikasha gen. et sp. nov. and Negodiaetictis rugatrulleum gen. et sp. nov., may represent Galictinae but are of uncertain subfamilial and tribal affinity. The fourth family is represented by the felid Pseudaelurus sp. indet. Tomarctus brevirostris is limited biochronologically to the Barstovian land mammal age and thus is consistent with the age indicated by other members of the Eastgate local fauna as well as by indirect tephrochronological dates previously associated with the Monarch Mill Formation. Actiocyon parverratis sp. nov. extends the temporal range of the genus Actiocyon from late Clarendonian back to the Barstovian. The Eastgate local fauna improves our understanding of mammalian successions and evolution, during and subsequent to the Mid-Miocene Climatic Optimum (∼14–17 Ma).

First report of bats (Mammalia: Chiroptera) from the Gray Fossil Site (late Miocene or early Pliocene), Tennessee, USA

Thousands of vertebrate fossils have been recovered from the Gray Fossil Site, Tennessee, dating to the Miocene-Pliocene boundary. Among these are but eight specimens of bats representing two different taxa referable to the family Vespertilionidae. Comparison of the fossils with Neogene and Quaternary bats reveals that seven of the eight specimens pertain to a species of Eptesicus that cannot be distinguished from recent North American Eptesicus fuscus. The remaining specimen, a horizontal ramus with m3, is from a smaller vespertilionid bat that cannot confidently be assigned to a genus. Although many vespertilionid genera can be excluded through comparisons, and many extinct named taxa cannot be compared due to nonequivalence of preserved skeletal elements, the second taxon shows morphological similarities to small-bodied taxa with three lower premolar alveoli, three distinct m3 talonid cusps, and m3 postcristid showing the myotodont condition. It resembles especially Nycticeius humeralis and small species of Eptesicus. Eptesicus cf. E. fuscus potentially inhabited eastern North America continuously since the late Hemphillian land mammal age, when other evidence from the Gray Fossil Site indicates the presence in the southern Appalachian Mountains of a warm, subtropical, oak-hickory-conifer forest having autochthonous North American as well as allochthonous biogeographical ties to eastern Asia and tropical-subtropical Middle America.

A late-surviving apatemyid (Mammalia: Apatotheria) from the latest Oligocene of Florida, USA

A new species of Apatemyidae, Sinclairella simplicidens, is based on four isolated teeth that were screenwashed from fissure fillings at the late Oligocene Buda locality, Alachua County, Florida. Compared to its only congener Sinclairella dakotensis, the new species is characterized by upper molars with more simplified crowns, with the near absence of labial shelves and stylar cusps except for a strong parastyle on M1, loss of paracrista and paraconule on M2 (paraconule retained but weak on M1), lack of anterior cingulum on M1–M3, straighter centrocristae, smaller hypocone on M1 and M2, larger hypocone on M3, distal edge of M2 continuous from hypocone to postmetacrista supporting a large posterior basin, and with different tooth proportions in which M2 is the smallest rather than the largest molar in the toothrow. The relatively rare and poorly-known family Apatemyidae has a long temporal range in North America from the late Paleocene (early Tiffanian) to early Oligocene (early Arikareean). The new species from Florida significantly extends this temporal range by roughly 5 Ma to the end of the Paleogene near the Oligocene-Miocene boundary (from early Arikareean, Ar1, to late Arikareean, Ar3), and greatly extends the geographic range of the family into eastern North America some 10° of latitude farther south and 20° of longitude farther east (about 2,200 km farther southeast) than previously known. This late occurrence probably represents a retreat of this subtropically adapted family into the Gulf Coastal Plain subtropical province at the end of the Paleogene and perhaps the end of the apatemyid lineage in North America.