Tulepyge tulensis, Adrain & Westrop, 2006
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publication ID |
https://doi.org/ 10.5281/zenodo.13651803 |
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persistent identifier |
https://treatment.plazi.org/id/576087F3-6303-6408-FFF9-85A7033BF8DD |
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treatment provided by |
Felipe |
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scientific name |
Tulepyge tulensis |
| status |
sp. nov. |
Tulepyge tulensis View in CoL sp. nov
Figs. 3, 4
Derivation of the name: After the Tule Valley. Type locality and horizon: Holotype, cranidium, SUI 100169 View Materials , and paratypes SUI 100170–100195 View Materials , all from Section B 1.1 m, Barn Canyon Member, House Formation ( lower Skullrockian ), southern House Range , Ibex area , Millard County, western Utah.
Diagnosis.— Cranidium with relatively dense tuberculate sculpture, variable from somewhat subdued to coarse and thorn−like; anterior border furrow short (exsag.) and incised; preglabellar field short; librigena with accessory tubercles in addition to single main row on field; eye socle with inflated anterior lobe; librigenal lateral border densely tuberculate, with raised lines confined to near lateral edge; pygidium long relative to width, with prominent transverse tubercle rows on posterior pleural bands and more posteriorly arcuate, though variable, posterior margin.
Description.—Cited proportions are based on measurements of the illustrated specimens. Where there is variation, the mean value is reported followed by the range in parentheses.
Cranidium .—Sagittal length 67 percent width across posterior fixigenae and 87 (84–90) percent width across midlength of palpebral lobes; glabella (excluding LO) with sagittal length 111 (104–117) percent maximum width across L1; entire cranidium with background sculpture of fine, densely spaced granules; anterior border short, longer sagittally than exsagittally, with strong dorsal convexity, sculpture of fairly large, closely spaced tubercles on dorsal and anterodorsal aspect and fine raised lines running subparallel to margin on anteroventral aspect; anterior border gently bowed in anterior profile, ventral margin bowed over about 50% of middle part of course, cut by transverse connective sutures on abaxial parts; anterior border furrow short (sag.; exsag.) and deep, with somewhat irregular course and depth, shallower medially in many specimens; preglabellar field short, quite steeply inclined in sagittal profile, in most larger specimens not bearing tubercles directly in front of glabella, though smaller specimens typically have two or three tiny tubercles in this area; interocular fixigena and frontal area grade into each other with increasingly steep slope in front of palpebral lobe; eye ridge not discernible dorsally, but very faintly expressed ventrally (Fig. 3A 5, especially left hand side), running from anterior edge of palpebral lobe obliquely forward toward preglabellar furrow; interocular fixigena with sculpture of moderate sized tubercles in approximately three exsagittal ranks, in many specimens with scattering of finer tubercles interspersed among them; small cranidia ( Fig. 4E View Fig 1 View Fig ) with only a single row of three large tubercles posteriorly and smaller tubercle anteriorly; sculpture on frontal area similar to that on interocular fixigena; anterior sections of facial suture slightly anteriorly convergent in front of palpebral lobe, changing course oppo−
Fig. 3. Tulepyge tulensis gen. et sp. nov., from the Barn Canyon Member, House Formation (Lower Ordovician; lower Skullrockian), Section B 1.1 m, Ibex Ą area, Millard County, western Utah. A. Cranidium , holotype, SUI 100169, dorsal (A 1), right lateral (A 2), anterior (A 3), oblique (A 4), and ventral (A 5) views.
B. Cranidium, SUI 100170, dorsal (B 1), left lateral (B 2), and anterior (B 3) views. C. Cranidium, SUI 100171, dorsal (C 1), left lateral (C 2), and anterior (C 3) views. D. Cranidium, SUI 100172, dorsal (D 1), anterior (D 2), and right lateral (D 3) views. E. Cranidium, SUI 100173, dorsal (E 1), left lateral (E 2), and anterior (E 3) views. F. Cranidium, SUI 100174, dorsal (F 1), anterior (F 2), and right lateral (F 3) views. G. Cranidium, SUI 100175, dorsal (G 1), anterior (G 2), and right lateral (G 3) views. H. Cranidium, SUI 100176, dorsal (H 1), anterior (H 2), and right lateral (H 3) views. I. Cranidium, SUI 100177, dorsal (I 1), left lateral (I 2), and anterior (I 3) views. All ×10.
site anterior part of frontal area to become more strongly anteriorly convergent; palpebral furrow well impressed, ranging from nearly straight in some specimens (e.g., Fig. 3A 1) to laterally bowed in others (e.g., Fig. 3G 1); palpebral lobe narrow, slightly inclined from transverse plane, with two or three small tubercles which are more prominent in smaller specimens, lateral margin more strongly curved slightly posterior to midlength; posterior fixigena gradational with interocular fixigena, sculpture continued posteriorly but more subdued in that direction; posterior fixigena quite long (exsag.) behind palpebral lobe, tapering in length distally but still well expressed and bearing tubercles near tip of posterolateral projection; posterior border furrow well incised, slightly shallower than axial furrow, increasing in length (exsag.) and shallower distally; posterior border with strong dorsal convexity, very short near contact with LO, increasing in length slightly to fulcrum, then strongly distal to fulcrum; border with sculpture of single transverse row of moderate sized tubercles, typically 3–4 in total, some specimens with widely scattered interspersed smaller tubercles, particularly distally, small specimens ( Fig. 4B View Fig 1, C 1 View Fig ); tiny posterolaterally directed spine at distal tip of posterior border, reduced to tubercle in largest specimens (Fig. 3A 1); doublure under LO with closely spaced raised lines on articulating surface; doublure scarcely developed elsewhere except for very short (exsag.) strip, lengthening slightly distally, beneath posterior border; no fossulae for hypostome articulation are discernible.
Librigena.—Field with minimum width 64 percent (59–71) maximum width at posterior edge of eye, minimum width 30 percent (25–36) of length; field with very fine background sculpture of caecal pits, with exsagittal row of 5–6 prominent tubercles set nearer to eye than to lateral border furrow, with small number of much smaller tubercles scattered irregularly above, below, and among main row; eye socle of single narrow band along posterior three quarters, expanded into distinct inflated lobe anteriorly, set off from field by narrow but strongly incised furrow; visual surface not preserved on any specimen, but eye large and long, occupying about two thirds length (exsag.) of field; lateral border furrow narrow and deep anteriorly, with shallower gradation toward field but sharp break of slope toward border, shallower posteriorly and almost or completely shallowed in front of base of genal spine; posterior border furrow not evident, almost entirely restricted to cranidium; lateral border furrow and librigenal lateral margin bowed moderately ( Fig. 4H, J View Fig ) or more commonly quite strongly ( Fig. 4I View Fig 2, J 2 View Fig ) laterally; lateral border with sculpture of prominent tubercles of same size as largest on field, arranged somewhat haphazardly but with suggestion of one or two exsagittal rows, with smaller tubercles fairly densely interspersed, and raised lines with completely linear expression developed subparallel with lateral margin on very edge of external aspect and ventrolateral aspect of border; anterior projection long; connective suture with shallow “V” shape, indicating rostral plate may have been hourglass−shaped; genal spine short and thorn−like, tapering rapidly to sharp point, with tuberculate and raised line sculpture of lateral border continued to point; doublure broad, turned sharply inward to form edge at contact with lateral border, lacking obvious raised line sculpture, with shallow Panderian notch posteriorly near posterior section of facial suture.
Rostral plate, hypostome, and thorax unknown.
Pygidium.—Sagittal length 53 percent (50–57) of maximum width; axis with sagittal length 95 percent (87–99) maximum anterior width and 84 (78–90) percent sagittal length of pygidium, anterior width of axis 42 (41–44) percent maximum width of pygidium; pygidium strongly vaulted in both sagittal and transverse (posterior) profile; posterior margin more or less chevron−shaped in dorsal view, nearly flat in transverse profile, with only subtle posteromedian flexure in some specimens (e.g., Fig 4P View Fig 2 View Fig ); axis dorsally inflated, with four well defined axial rings and very faint fifth not well differentiated from terminal piece but marked by small fifth pair of paired axial tubercles in most specimens; rings very slightly longer sagittally than exsagittally, with sculpture of large pair of tubercles, smaller median tubercle (variably present) and two or three smaller lateral tubercles on either side; crescentic articulating half ring similar in sagittal length to first ring; ring furrow short and deeply incised; second and third ring furrows progressively less well incised but transversely complete, third expressed mostly laterally, fourth very weakly expressed; prominent pseudoarticulating half rings present on second and third segments, merged and indistinct posteriorly; axial furrows sharply posteriorly convergent opposite first ring, more weakly posteriorly convergent opposite rings 2–5, shallowed posteriorly to only very weakly circumscribe rear of axis, which is mostly marked by break in slope, axial furrow deflected in course around lateral inflations of rings; pleural furrow distinct on first three segments, fourth very weakly expressed, of same length proximally and distally, shallow near axial furrow, contact with axial furrow weakly defined, much deeper across fulcrum and distally; anterior pleural band of approximately same length (exsag.) as posterior band, both bands of same length proximally and distally, and bands of first, second, and third segments of similar length; anterior pleural band lacking sculpture, posterior band with transverse row of moderate tubercles, slightly smaller than those on axial rings, and interspersed smaller tubercles; interpleural furrows weakly expressed, but first three discernible, progressively weaker posteriorly; pleural region proximal to fulcrum horizontal or slightly downsloping, region distal to fulcrum sharply downturned; pleural bands terminate in strongly inflated axis; anterior bands simply terminate against edge of border, posterior bands developed into sharp ridge and distal tip, merging with border to give inner edge of border scalloped appearance; border rim−like, with prominent sculpture of subparallel raised lines, mostly contiguous across entire width of border; doublure narrow, describing shallow “V” shape in ventral views, with raised line sculpture similar to that on pygidial border.
Discussion.— Tulepyge tulensis is distinguished from T. paucituberculata in its dorsal cranidial sculpture of relatively smaller but densely packed tubercles, more anteriorly inflated versus narrow glabella, shorter preglabellar field and frontal area, less transversely arched anterior border (in anterior view), slightly broader interocular fixigena, narrower librigena field with more accessory tubercles in addition to prominent main exsagittal row, relatively slightly shorter genal spine, denser tuberculate sculpture on the librigenal lateral border, raised lines restricted to lateralmost aspect of Material and occurrence.—In addition to type material lisexternal surface of librigenal lateral border versus distributed ted by Fortey (1983: 185), figured material including GSC over about half of external area of border, raised lines contig− 69590 ( Kindle 1982: pl. 1.5: 22; Fig. 5A herein), and GSC uous versus somewhat irregular and noncontiguous (Fig. 30023–30029 ( Fig. 5), all from boulder BPS 496, Broom 5F), and longer pygidium with broader pleural areas and Point Member, Green Point Formation, Broom Point South more rounded, versus strongly “V” shaped posterior margin section, Broom Point, western Newfoundland, Canada; colin dorsal view. lected by C.H. Kindle.
Data emerging from study of well constrained, large, and Discussion.—When Fortey (1983) described the species he well preserved silicified samples of Upper Cambrian and based it on four illustrated specimens all from a single boul− Lower Ordovician species ( Adrain et al. 2001, 2003; Adrain der in the conglomerate Unit 57 of James and Stevens (1986) and Westrop 2004, 2005, 2006) indicate that ranges of intra− at Broom Point South. He also assigned two cranidia which specific variation are much less than those often invoked in the he had illustrated previously (in Fortey et al. 1982: pl. 3: 14, systematic trilobite literature. In this context, it is important to 17). One (ROM 39623; pl. 3: 14) was from a different boulnote that Tulepyge tulensis displays genuine variation that is der in Unit 57 at Broom Point South, and the other (ROM quite striking, especially in the degree of development of dor− 39627; pl. 3: 17) from a boulder in the same bed at Broom sal cranidial tuberculate sculpture. This ranges from fairly Point North. From this latter boulder he also (Fortey et al. subdued in the holotype specimen (Fig. 3A), with the tuber− 1982: pl. 3: 12, 15) figured a cranidium assigned to “ Pseudocles on the anterior border scarcely interrupting the arc of the hystricurus sp. aff. P. rotundus Ross. ” Fortey recognized anterior margin, through more coarsely tuberculate examples (1983: 186) that the cranidia thus assigned to paucituber− (Fig. 3B) with background tuberculation on the glabella in− culata implied a wide range of variation in the expression of creased and the anterior margin of the anterior border clearly cranidial tuberculate sculpture. In the absence of other inforinterrupted by forwardly projecting tubercles, to extreme ex− mation, such a range would be worrisome in specimens deamples (Fig. 3C) in which the larger tubercles are extended rived from different source boulders. As discussed above, into very short conical spines and the anterior margin is ren− however, a similar range of variation is present in the same dered highly irregular by the spines. Variation in tubercle/ feature in the sample of T. tulensis , all of which is from a sinspine expression is common ontogenetically in densely tuber− gle tightly constrained in situ horizon. The amount of variaculate trilobites, with the typical trajectory from more coarsely tion in the Newfoundland species is confirmed by additional tuberculate to progressively less coarse with larger size. This material from a single boulder, BPS 496, illustrated in Fig. 5, can be observed to a degree within T. tulensis , as small in which sculpture ranges from subdued ( Fig. 5D 1 View Fig ) to coarse cranidia ( Fig. 4B–D View Fig ) are uniformly strongly tuberculate and ( Fig. 5A 1 View Fig ). Given this range of variation, the cranidium asonly larger cranidia (Fig. 3A, F, H) have subdued sculpture. signed by Fortey (1982: pl. 3: 12, 15) to “ Pseudohystricurus ” However, the cranidia illustrated in Fig. 3A–C are of nearly seems also to represent T. paucituberculata , to which it is reidentical large size and the variation in large holaspid sculp− assigned herein. Fortey (1983) assigned a cranidium illusture is real. As reflected by the ratios reported in the above de− trated by Kindle (1982: pl. 1.5: 22) with question to pauciscription, librigenae vary quite widely in their dimensions, tuberculata. This specimen is refigured herein ( Fig. 5A). It, mostly obviously in the width of the field. Pygidia vary in their too, falls clearly within the range of sculptural variation conrelative sagittal length, and in the shape in dorsal view of the firmed by multiple specimens from the same boulder illusposterior margin, ranging from more arcuate ( Fig. 4O View Fig 1 View Fig ) to trated in Fig. 5, and doubt about its assignment is removed.
more “V” shaped ( Fig. 4K View Fig 3), though none approaches the strong “V” shape of the only known pygidium of T. paucituberculata ( Fortey 1983: pl. 23: 5). Acknowledgements
Tulepyge paucituberculata ( Fortey, 1983) View in CoL
We are grateful to Tiffany Adrain (University of Iowa, Iowa City, USA)
Fig. 5.
for assistance with SUI numbers, to Jean Dougherty (Geological Survey 1982 Hystricurus sp. ; Kindle 1982: pl. 1.5: 22. of Canada, Vancouver) for GSC numbers and for arranging a loan of 1982 Hystricurus sp. nov.; Fortey in Fortey et al. 1982: 108, pl. 3: 14, GSC 69590, and to Brian D.E. Chatterton (University of Alberta, Ed− 17. monton, Canada), Gregory D. Edgecombe (Australian Museum, Syd− 1982 Pseudohystricurus sp. aff. P. rotundus Ross ; Fortey in Fortey et ney), and Richard A. Fortey (Natural History Museum, London, UK) for al. 1982: 113, pl. 3: 12, 15. helpful reviews. Preparation of the paper was supported by ( US) Na− 1983 Hystricurus paucituberculatus Fortey 1983: 185 , pl. 23: 1–7. tional Science Foundation grants EAR 9973065 and EAR 0308685.
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