Wilsonium brevipinne ( Cope, 1893 )

Liu, Juan, 2021, Redescription of ‘ Amyzon’ brevipinne and remarks on North American Eocene catostomids (Cypriniformes: Catostomidae), Journal of Systematic Palaeontology 19 (9), pp. 677-689 : 679-681

Wilsonium brevipinne ( Cope, 1893)

( Figs 2 , 3 , 4A , 5 )

1893 Amyzon brevipinne Cope : 402.

1906 Amyzon brevipinne Cope, 1893 ; Lambe: 154.

1977 Amyzon brevipinne Cope, 1893 ; Wilson: 23–32, fig. 8.

Holotype. CMNFV 6189, a fish preserved in right lateral view lacking the caudal fin ( Fig. 2 ).

Referred materials. Well-preserved skeletal specimens: UALVP 12159, a nearly complete fish; UALVP 12658, a nearly complete fish lacking the tail; UALVP 12610, a complete right frontal; UALVP 31585, a right pharyngeal bone with teeth; ROM 11160, a pharyngeal bone with teeth; ROM 11163, a nearly complete fish.

CMN collection: CMNFV 2042, 2046, 2050, 2054, 2055, 2057, 2066, 2068, 2069, 2071–2074, 2090, 2092, 2097, 2099, 2104, 34480–34492, 34509, 34820, 34821, 348883, 34885, 34888, 34891, 34893–34899, 41745 and 41746. Specimens listed together under NMC 3132 in Wilson (1977) are re-catalogued within CMNFV 34480–34899. CMNFV 6195(a, b) and 25266 from Tranquille area are identified as Wilsonium .

UALVP collection: UALVP 12104, 12133, 12462–12464, 12480, 12481, 12483, 12487, 12496, 12509, 12512, 12514–12517, 12519–12521, 12525–12529, 12532–12534, 12537–12539, 12541, 12542, 12545–12547, 12549, 12553–12556, 12558, 12561, 12563–12566, 12568–12570, 12572–12577, 12580, 12583, 12584, 12586–12589, 12591, 12593, 12595, 12597–12599, 12601, 12602, 12605, 12606, 12611–12613, 12616, 12617, 12619, 12621–12626, 12631–12636, 12638, 12639, 12641–12645, 12647, 12651–12654, 12661–12680, 12682–12684, 12686–12689, 12691–12698, 12700–12708, 12710, 12711, 12714–12716, 12719–12729, 12731, 12733–12736, 12743–12746, 12750, 12754, 12757, 12762, 12763, 12767, 12768, 12770–12772, 12775, 12777–12779, 12783–12785, 12787–12790, 12794–12798, 12800–12804, 12806, 12807, 12810, 12812, 12813, 12819, 12820, 12825–12828, 12830, 12831, 12835, 12837–12843, 12845–12847, 12850, 12854–12858, 12860–12864, 12866, 12867, 12869, 12878, 12879, 12884, 12888, 12889, 12893–12904, 12906, 12907, 12910, 12912–12921, 12923, 12957, 12969, 12978, 12981, 12987, 12989, 12991, 12992, 13006, 13008, 13012, 13019, 13021, 13037, 13054, 13071, 13072, 13078, 13085, 13089, 13097, 13114–13126, 13129, 13131–13135, 13137–13144, 13146, 13147, 13149, 13150, 13152–13174, 13177, 13182, 13184, 13187, 13435, 14730, 14731, 14735, 14737, 14738, 14745–14748, 14754, 14755, 14759, 14760, 15912–15915, 17836, 21262–21339 and 27140.

ROM collection: ROM 11161, 11162, 11164, 11166, 11167, 11169–11171, 11179, 11182, 11370, 11377, 11379, 11382, 11387, 11389, 11461, 11468 and 19420.

Age and horizon. Allenby Formation, early Eocene.

Type locality. North Fork of the Similkameen River (Tulameen Rivers), probably in Pleasant Valley (Princeton area), British Columbia, Canada ( Wilson 1977).

Additional localities. Whipsaw Creek, Blakeburn Mine areas, and Tulameen, all in British Columbia, Canada.

Revised diagnosis. Small-sized and shallow-bodied Eocene catostomid, BD/SL 0.20–0.32, HL/SL 0.30–0.40, D 12–18, A 7–10, pharyngeal teeth about 20 on each pharyngeal bone, frontal bone nearly rectangular with elongated orbital notch, supraorbital present, infraorbital series including shallow and slender lacrimal, posteroventral process of dentary short, opercle broad with OPW slightly larger than OPH, neural complex oval in shape, rib 4 not very robust with length shorter than half the regular rib, PFL about 1/2 PL, PSL sub-equal to PL, hypural 3 not fused to compound centrum.

Figures

Figure 2. The holotype (CMNFV 6189) of Wilsonium brevipinne from the Eocene Allenby Formation, probably from the Pleasant Valley locality, British Columbia, Canada. Arrow indicates the frontal bone. Scale bar = 10 mm.

Figure 3. A juvenile or young adult and skulls of Wilsonium brevipinne from the Eocene Allenby Formation, Blakeburn Mine, British Columbia, Canada. A, juvenile or young adult, UALVP 12159; B, skull of UALVP 12658; C, line drawing of composite skull based on UALVP 12159 and UALVP 12658. Arrows indicate the frontal bones. Abbreviations: aa, anguloarticular; c1–4, the space for centra 1 through 4; d, dentary; e, ethmoid; fr, frontal; hm, hyomandibular; iob, infraorbitals, iob 1 (lacrimal) through iob 5 numbered from anterior to posterior; iop, interopercle; ke, kinethmoid; le, lateral ethmoid; m, maxilla; nc, neural complex; ns4, neural spine of the 4th vertebra; op, opercular; p, palatine; pa, parietal; pm, premaxilla; pop, preopercle; pt, pterotic; q, quadrate; r4, the 4th rib or rib of the 4th vertebra (also known as outer arm of os suspensorium in some taxa); ra, retroarticular; so, supraorbital; soc, supraoccipital; sop, sub-opercle; sp, sphenoid. Scale bars: A = 10 mm; B = 5 mm.

Figure 4. Comparison of the frontal bones of Wilsonium, Amyzon and Plesiomyxocyprinus. A, frontal of Wilsonium brevipinne from the Eocene Allenby Formation, Blakeburn Mine, British Columbia, Canada, UALVP 12610; B, frontal of Plesiomyxocyprinus arratiae from the Eocene Huadian Formation, Huadian, Jilin, China, IVPP V 15711.29 (images modified from Liu & Chang 2009, fig. 2a, b); C, frontal of Amyzon aggregatum from the Eocene of Horsefly, British Columbia, Canada, UALVP 32931. A, B, dorsal view; C, medial view. Anterior is to the top. Abbreviations: fpf, fronto-parietal fontanelle; obp, orbital process of frontal; on, orbital notch of frontal. Scale bars = 5 mm.

Figure 5. Disarticulated bones and reconstructions of Wilsonium brevipinne from the Eocene Allenby Formation. A, C, anterior to the left; B, D–F, anterior to the right. C and D in medial view; A and C in posteroventral view; and the rest in lateral view. A, pharyngeal bone and teeth, UALVP 31585a; A’, line drawing of pharyngeal bone and teeth based on UALVP 31585a; B, opercle, UALVP 12796; C, interopercle, UALVP 12616; D, vomer; ROM 11161a; E, caudal skeleton, ROM 11161a; E’, line drawing of caudal skeleton, ROM 11161a; F, mandible including dentary, articular, and retroarticular, ROM 11161. Abbreviations: aa, anguloarticular; aaf, anguloarticular fossa for articulation with the quadrate; arp, auricular process of opercle; avp, anteroventral process; cc, compound centrum of caudal skeleton; cp, coronoid process of dentary; den, dentary; emp, preethmoid process; ep, epural; gr, gnathic ramus of dentary; hyp1–5, hypural 1 through 5; opa, opercular arm; opf, opercular fossa; pls, pleurostyle; pt, pharyngeal teeth; r4, rib 4; ra, retroarticular. Scale bars = 5 mm.