Scotiophryne pustulosa ESTES, 1969

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 : 81-83

Scotiophryne pustulosa ESTES, 1969

( Text-fig. 3a–k )

M a t e r i a l a n d o c c u r r e n c e s: Maxilla and ilia from Mesaverde Formation, Wyoming, USA; maxillae, squamosals, frontoparietals, and fragmentary skull bones from Kaiparowits Formation, Utah, USA; ilia from Wahweap Formation, Utah, USA; and maxilla from Fruitland Formation, Utah, USA (Appendix 2). Also reported on the basis of isolated bones from older (Aptian – Albian and late Santonian – early Campanian) and younger (late Maastrichtian and early Paleocene) rock units in the Western Interior of USA and Canada and, outside of the Western Interior, in the Campanian of both Baja California, Mexico and New Jersey, USA (see “Remarks”, below).

D e s c r i p t i o n: Specimens figured here ( Text-fig. 3a–k ) are two incomplete maxillae, a fragmentary squamosal, and two fragmentary frontoparietals from the Kaiparowits Formation, Utah. Both maxillae ( Text-fig. 3a–d ) are from the right side and are broken anteriorly and posteriorly. Each preserves the middle and posterior portions of the suborbital region and varying amounts of the postorbital region. The processus pterygoideus is broken on both specimens. Neither maxilla has any intact teeth, however, OMNH 67105 ( Text-fig. 3d, e : arrow), preserves a replacement tooth crown in situ and its posteriorly intact tooth row extends a short distance beyond the level of the broken base of the processus pterygoideus. These maxillae are from comparably-sized individuals and resemble similarly incomplete maxillae of the species previously reported by Roček et al. (2010: fig. 16Aj–l, Bd) from the Kaiparowits Formation. Both squamosals (only one example is depicted in Text-fig. 3f, g ) are from the left side and preserve the dorsal portion (processus posterodorsalis) of the lamella alaris. Two fragmentary, left frontoparietal specimens are available: OMNH 67109 consists of the anterior end, whereas OMNH 67110 preserves the bone adjacent to the posterior portion of the margo orbitalis and the processus lateralis ( Text-fig. 3h, i and j, k , respectively).

Collectively, the figured specimens most closely resemble homologous, referred cranial bones of Scotiophryne pustulosa from the Bug Creek Anthills locality (mixed late Maastrichtian and early Paleocene ; Hell Creek Formation ), Montana, and from the Lance Formation (late Maastrichtian ), Wyoming, in the following features (cf. Estes 1969: fig. 2; Gardner 2008: fig. 13.1L– T): moderate size; external surfaces ornamented with a shagreen of small, bead-like tubercles; on the maxilla teeth are present, the processus zygomatico-maxillaris is moderately tall (i.e., extends a noticeable distance above the level of the margo orbitalis) and is grooved dorsally for contact with the squamosal, the lamina horizontalis is moderately deep and lingually wide, and has a convex lingual surface, and judging by their broken bases, the processus pterygoideus was at least moderately prominent; the dorsal portion of the squamosal is bluntly rounded and its smooth edges indicate it did not contact other skull bones; and the frontoparietals were paired and not in broad contact anteriorly with the nasals, although they likely at least partially overlapped the sphenethmoid .

R e m a r k s: The monotypic species Scotiophryne pustulosa has the distinction of being the first Cretaceous anuran species to be named from North America (Estes 1969). The holotype is an ilium, but more distinctive are the referred skull bones (maxilla, squamosal, nasal, and frontoparietal) bearing the characteristic bead-like or pustulate ornament that inspired the specific epithet. The skull bones figured here from the Kaiparowits Formation are assigned to S. pustulosa because they closely resemble geologically younger (late Maastrichtian and?early Paleocene) examples of the same bones previously referred to the species (Estes 1969: fig. 2; Gardner 2008: fig. 13.1L–T) and because they conform to the most recent, revised diagnoses for S. pustulosa ( Gardner 2008, Roček 2013). The newly reported maxillae and squamosals provide no new information about these elements in S. pustulosa , because these specimens are less complete than examples previously reported from the Bug Creek Anthills and the Lance Formation. The new frontoparietal specimens confirm that these bones were paired and one (OMNH 67110: Text-fig. 3j, k ) provides new information about the more posterior portion of this bone, as follows: the margo orbitalis is broadly concave medially and laterally overhangs the braincase wall; the processus lateralis projects only a short distance laterally and is blunt in dorsal or ventral outline; medial to the margo orbitalis and processus lateralis, the ventral surface bears a ventrally projecting flange (pars contacta) that extends anteroposteriorly (the anterior continuation of this flange can be seen on the other frontoparietal, OMNH 67109: Text-fig. 3i ); and more medially the ventral surface bears a shallow, ventrallyprojecting, bony patch that represents part of an incrassatio frontoparietalis. Unfortunately, OMNH 67110 is too fragmentary to establish further details about the incrassation, such as its outline and extent.

Originally described from the late Maastrichtian and early Paleocene of Montana and Wyoming (Estes 1969), Scotiophryne since has been reported from at least nine formations of Campanian – Paleocene age in the Western Interior of Canada and the USA (see summaries by Gardner 2008, Roček 2013, Gardner and DeMar 2013). Ours is not the first report of S. pustulosa from the Kaiparowits Formation. Eaton et al. (1999: table 11) included the species in a faunal list for the formation and subsequently Roček et al. (2010: 379, fig. 16Aj–l and Bd) described incomplete S. pustulosa maxillae from UMNH locality VP 108 in the lower part of the formation. Skull bones reported here come from localities in both the lower (OMNH V9) and upper (OMNH V5 and V61) parts of the Kaiparowits Formation, and demonstrate that S. pustulosa was broadly distributed stratigraphically through the formation. Other Judithian reports for Scotiophryne in the Western Interior (see Appendix 2) are in the Mesaverde Formation in Wyoming ( Breithaupt 1985, DeMar and Breithaupt 2006, 2008), the upper (Judithian) portion of the Wahweap Formation in Utah ( Roček et al. 2010), and the Fruitland Formation in New Mexico ( Armstrong-Ziegler 1978, 1980, Hunt and Lucas 1992, 1993). Roček et al. (2010) also reported slightly older occurrences for the species (all founded on ilia) at three localities in south-central Utah: one locality in the lower (early Campanian) part of the Wahweap Formation ( Roček et al. 2010: fig. 13a, b, d); a second locality of similar age that may also lie in the Wahweap Formation ( Roček et al. 2010: fig. 14t); and a late Santonian age locality in the John Henry Member of the Straight Cliffs Formation ( Roček et al. 2010: fig. 10B). The last is likely the oldest occurrence for the species. Recently, Oreska et al. (2013) reported cf. Scotiophryne sp. on the basis of fragmentary skull bones (a maxilla and some indeterminate bones) from the middle part of the Cloverly Formation (Aptian – Albian) of Wyoming. Although their figured maxilla does bear pustulate ornament ( Oreska et al 2013: fig. 8A, B), considering that pattern of ornament is not unique among anurans to Scotiophryne and that the Cloverly specimens are at least 15 million years older than the oldest Utah examples, we (as did Oreska et al. 2013) suspect the Cloverly specimens do not pertain to Scotiophryne . Outside of the Western Interior, there are reports of Scotiophryne in two Campanian formations: the El Gallo Formation (possibly “Edmontonian” equivalent; see Cifelli et al. 2004, Kielan-Jaworowska et al. 2004) in Baja California, Mexico ( Estes and Sanchiz 1982) and the Marshalltown Formation (possibly Judithian or Aquilan equivalent; see Cifelli et al. 2004, Kielan-Jaworowska et al. 2004) in New Jersey, USA ( Denton and O’Neill 1998); neither occurrence can be verified, because the relevant specimens (skull and postcranial bones from Baja California; maxilla from New Jersey) have not been described or figured.

Figures

Text-fig. 3. Skull bones of Scotiophryne pustulosa ESTES, 1969 and cf. Scotiophryne sp. from the middle – late Campanian (Judithian) of Utah and Montana, USA. All images are photographs and most depict specimens lightly dusted with ammonium chloride to enhance details and texture. Images at different magnifications; see corresponding scale bars. a–k – Scotiophryne pustulosa ESTES, 1969, all from Kaiparowits Formation, OMNH locality V9, Utah: a, b – incomplete right maxilla, OMNH 67093, in labial (a) and lingual (b) views; c–e – incomplete right maxilla, OMNH 67105, entire specimen in labial (c) and lingual (d) views and close up (e) of partially obscured, in situ replacement tooth crown (arrow) in lingual view; f, g – dorsal part of left squamosal, OMNH 67107, in lateral (f) and medial (g) views; h, i – anterior part of left frontoparietal, OMNH 67109, in dorsal (h) and ventral (i) views; j, k – median part of left frontoparietal, OMNH 67110, in dorsal (j) and ventral (k) views. l, m – cf. Scotiophryne sp., incomplete left maxilla, AMNH FARB 33045, in labial (l) and lingual (m) views, from Judith River Formation, Clambank Hollow, Montana.