1030


Journal of Paleontology


imaging. To minimize charging during electron imaging, the shale pieces were wrapped in copper foil tape with only the fossils exposed, and mounted so that the foil was in contact with the sample stage, thereby grounding surface electrical charge (Orr et al., 2002). High-resolution composite SEM images of specimens larger than the imaging area at the lowest magnifi- cation level (horizontal field width ~4mm) were assembled using Adobe Photoshop from multiple high-magnification images acquired under identical operating conditions (focus setting, brightness, contrast, dwell time, probe spot diameter, working distance, and VA). The EDS elemental maps in this study were collected at an accelerating voltage of 3 keV and a working distance of 12mmfor 400 s live time with ~200 counts/s and ~27% dead time. Elemental peaks were identified with the Bruker Esprit 1.9.2 software. To analyze variations in the relative mass and thicknesses


of the materials comprising the specimen, we imaged the part and counterpart using the BSE SSD in the compositional (atomic number, or Z) contrast imaging mode at successively higher beam energies (e.g., 5, 6, 7 keV, etc.) in order to acquire a series of images (see Muscente and Xiao, 2015, for a technical background on the acquisition of BSE SSD Z-contrast images and interpretation of beam-energy image series). Variations in the mass and thickness of materials in the uppermost few microns of a sample can be inferred from a beam-energy image series via consideration of ‘mass-thickness contrast,’ which manifests because, at each point in an electron beamraster scan, the number of beam electrons backscattered from the sample and used in image formation depends on the masses and thick- nesses of the materials within the volume of the sample inter-


acting with the electron beam (see Muscente and Xiao, 2015, fig. 1F). Because BSE emission depth increases with VA, elec- tron beam energy also affects mass-thickness contrast, and changes in mass-thickness contrast with VA follow predictable patterns, which are evident in a beam-energy image series. Thus, observations of changes in image contrast through beam-energy image series can be used to reconstruct the subsurface micro- structure of samples (Muscente and Xiao, 2015; Tang et al., 2017).


Repository and institutional abbreviation.—The material con- sists of the part and counterpart of the same specimen deposited in theVirginia Polytechnic Institute Geosciences Museum(VPIGM).


Systematic paleontology


Nomenclature for wing venation and abbreviations.—The description of wing venation follows terminology proposed by Béthoux and Nel (2001, 2002). Abbreviations of forewing vena- tion: ScA, ScP, anterior, posterior sub-costa vein; RA, RP, anterior, posterior radial vein; MA, MP, anterior, posterior media veins; MA1,MA2, first, second branch of anterior media vein; CuA, CuP, anterior, posterior cubitus veins; CuPa, anterior branch of cubitus vein; CuPa1, first branch of CuPa; CuA+CuPa1, fusion part of anterior cubitus vein and first branch of CuPa; CuPa2, posterior branch of CuPa; CuPb, second branch of CuP; ScA, ScP, anterior, posterior sub-costa vein; A, anal vein; 1A, firstbranchofanalvein.


Class Insecta Linnaeus, 1758 Order Orthoptera Olivier, 1789


Family Elcanidae Handlirsch, 1906


Subfamily Archelcaninae Gorochov, Jarzembowski and Coram, 2006


Genus Cascadelcana new genus


Type species.—Cascadelcana virginiana n. gen. n. sp.; by present designation.


Diagnosis.—As for type species.


Occurrence.—Upper Triassic (Norian), Cow Branch Forma- tion; Solite Quarry, near the North Carolina-Virginia boundary, United States.


Etymology.—The generic epithet is derived from Cascade, in reference to the town of Cascade near the Solite Quarry, and the common genus name Elcana.


Composition.—Only the type species, Cascadelcana virginiana n. gen. n. sp.


Remarks.—Casadelcana n. gen. differs from all other known genera of the Elcanidae in its forewing venation, in which the short CuA is almost vertical against the posterior margin and RP+MA1 have fewer branches.


Cascadelcana virginiana new genus new species Figures 2, 3


Holotype.—06/L4BH/2-1/107, VPIGM 4698, sex unknown, complete forewing, part and counterpart (Figs. 2, 3).


Diagnosis.—RP+MA1 with six branches; M with 2 branches before stem MA1 fused with RP; CuA short, almost vertical against the posterior margin.


Occurrence.—Upper Triassic (Norian), Cow Branch Forma- tion; Solite Quarry, near the North Carolina-Virginia boundary, United States.


Description.—Forewing: length 9.7mm, width 2.3mm at mid- length. ScA slightly S shaped, ending in anterior margin before 1/3 of total wing length. ScP ending in anterior margin close to half-length of forewing, giving off two or three distinct oblique branches ending in anterior margin. Stem R very strong, bran- ched near wing mid-length, RA trending up after split from R, and slightly waved in distal part. RA with 10 branches ending in anterior margin. Stem RP+MA1nearly straight, ending in wing apex, RP+MA1 with six simple branches, MA1 and MA2 diverging at 4.2mm distal of forewing base. Area between RA and RP broad. MP simple, originates after ScA ending in ante- rior margin, MP ending in posterior margin before 2/3 distal of forewing base. CuA short, originates before ScA ending in anterior margin, and almost vertical against the posterior margin. CuPa1 fused with CuA opposite M+CuA branch, CuPa2 simple, ending in posterior margin opposite to whereM branches. Area between CuA+CuPa1 and CuPa2 narrow. CuPb simple, ending in posterior margin before ScA ending in anterior margin. Anals simple, ending in posterior margin.


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