Theatonius, Gardner & Redman & Cifelli, 2016

Gardner, James D., Redman, Cory M. & Cifelli, Richard L., 2016, The Hopping Dead: Late Cretaceous Frogs From The Middle - Late Campanian (Judithian) Of Western North America, Fossil Imprint 72 (1 - 2), pp. 78-107 : 86

Theatonius n. sp.

( Text-fig. 5g, h )

M a t e r i a l a n d o c c u r r e n c e s: Six maxillae from

Kaiparowits Formation, Utah, USA (Appendix 2).

D e s c r i p t i o n: The six maxillary specimens inclu- de a fragmentary example from the UMNH collections previously figured as being from an unidentified anuran ( Roček et al. 2010: fig. 16Ab) plus five more recently identified examples from the OMNH collections: a nearly complete left maxilla (OMNH 67082; Text-fig. 5g, h ) and four less complete maxillae (unfigured). Collectively these six specimens document the entire structure of the maxilla. These specimens are strikingly similar to maxillae of the late Maastrichtian (Lancian) anuran Theatonius lancensis (see revised species diagnosis by Gardner 2008) in the following features: small size (OMNH 67082 is 4.9 mm long); labial surface ornamented with moderate-sized and closely packed pustules; crista dentalis moderately deep and lacks teeth; lamina horizontalis a weakly developed and lingually convex ridge; margo orbitalis deeply and asymmetrically concave; preorbital area taller and longer than postorbital area; processus palatinus relatively massive, projects linguodorsally, and dorsally bears a prominent facet; groove for ductus nasolacrimalis deep, wraps around labial base of processus palatinus and extends onto margo orbitalis; anterior portion of lamina anterior lingually bears a prominent facet; rostellum small, pointed, and directed anteriorly; processus pterygoideus lingually short, but anteroposteriorly elongate, and bears prominent articular facet that wraps posterodorsally onto processus zygomatico-maxillaris; and posterior end of processus posterior bluntly pointed.

R e m a r k s: As indicated above, maxillae reported here from the Kaiparowits Formation compare favourably with the type species Theatonius lancensis . The one notable difference is that the occlusolingual rim of the pars dentalis bears a row of tiny bumps in the Utah specimens, whereas that margin is smooth in the two maxillae (holotype and one referred: Gardner 2008: fig. 13.2A–D and E, respectively) described for Theatonius lancensis from the Lance Formation. That morphological difference, coupled with differences in ages (i.e., middle – late Campanian vs. late Maastrichtian), suggest the maxillae from the Kaiparowits Formation pertain to a second species of Theatonius . Unfortunately, no examples of the equally distinctive frontoparietals or squamosals comparable to those known for T. lancensis (see Fox 1976b, Gardner 2008: fig. 13.2F–J) have been identified among the Utah samples.

The occurrence of Theatonius in the Kaiparowits Formation of south-central Utah extends the geographical range for the genus southwards into Utah from Wyoming ( Fox 1976b) and Montana ( Gardner and DeMar 2013, Mercier et al. 2014) and extends its temporal range back from the late Maastrichtian to the middle – late Campanian. There also is an unconfirmed report of Theatonius -like squamosals in the Campanian (possibly Aquilan or Judithian equivalent; see Cifelli et al. 2004, Kielan-Jaworowska et al. 2004) Marshalltown Formation of New Jersey ( Denton and O’Neill 1998). Compared to the apparently restricted distribution of T. lancensis in the Lance Formation, where it is known only from the Bushy Tailed Blowout locality, the putative new species of Theatonius from Utah has a broader stratigraphic distribution, being represented at five localities in both the lower (OMNH V6 and V9; UMNH VP 108) and upper (OMNH V5 and 61) parts of the Kaiparowits Formation.

Figures

Text-fig. 5. Edentulous anuran maxillae from the middle – late Campanian (Judithian) of Alberta, Canada and Utah, USA. All images are photographs and depict specimens lightly dusted with ammonium chloride to enhance details and texture. Images at different magnifications; see corresponding scale bars. a–f – Tyrrellbatrachus brinkmani GARDNER, 2015, all from basal part of Dinosaur Park Formation, Dinosaur Provincial Park,Alberta: a, b – incomplete right maxilla, TMP 1985.066.0035 (holotype), in labial (a) and lingual (b) views, from TMP locality L0404; c, d – incomplete right maxilla, TMP 1986.033.0033, in labial (c) and lingual (d) views, from TMP locality L0031; e, f – incomplete left maxilla, TMP 1986.214.0032, in labial (e) and lingual (f) views, from TMP locality L0051. g, h – Theatonius n. sp., nearly complete left maxilla, OMNH 67082, in labial (g) and lingual (h) views, from Kaiparowits Formation, OMNH locality V6, Utah.