Amapondella amapondense ( van Hoepen, 1921 )

Ifrim, Christina & Stinnesbeck, Wolfgang, 2021, Ammonoids and their biozonation across the Santonian-Campanian boundary in north-eastern Coahuila, Mexico, Palaeontologia Electronica (a 34) 24 (3), pp. 1-62 : 46-48

Amapondella amapondense ( van Hoepen, 1921)

Figure 36A–E , Figure 37A–E , Table 15

1921 Heteroceras amapondense van Hoepen , p. 17, plate 4, figures 1, 2

1969 Anaklinoceras (?) stephensoni Collignon , p. 50, plate 532 (figure 2096)

1969 Hyphantoceras reussianum d’Orb. ; Collignon, p. 29, plate 523 (figure 2064), p. 38, plate 527 (figures 2079–2080); p. 48, plate 531 (figure 2095)

1978 Hyphantoceras (Madagascarites?) amapondense (van Hoepen) ; Summesberger, p. 123, plate 3, figure 19; text-figure 13

1983 Hyphantoceras amapondense (van Hoepen) ; Lewy, p. 24, figures 1-6 (with synonymy)

1985 Hypthantoceras (Madagascarites) amapondense ( van Hoepen, 1921) ; Klinger, p. 6, figure 41-k

1991 Hyphantoceras (?) amapondense ( van Hoepen, 1921) ; Kennedy, p. 181, figure 9.9, 9.10

1997 Eubostrychoceras (Amapondella) amapondense van Hoepen ; Klinger and

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Kennedy, p. 244, figures 12- 14a, 15a-d, 17a-c

2003 Eubostrychoceras (Amapondella) amapondense (van Hoepen) ; Klinger and Kennedy p. 235, figures 5–6, 7a, 8a–d, 9a–c (with synonymy)

2007 Amapondella amapondense ( van Hoepen, 1921) ; Klinger and Kennedy, p. 101, figures 5a–c, 10i–j, 11, 12b–i, 13a– e, m

Type. Holotype is the specimen figured by van Hoepen (1921, plate 4, figures 1–2) by original designation. It is from the upper Santonian or lower Campanian of the Mzamba Formation at the type section (locality 1), Eastern Cape Province, South Africa. SAM-PCZ18722 is a cast of the holotype.

Material. Five specimens, CPC –2345 to 2347 from bed TPY50, CPC –2351 to –2352 from bed TPY25 .

Description. Open, slightly helicoidal, more or less even coiling, U/D is ca. 0.47. Circular to more subquadrate whorl sections at larger D, while ovoid whorl sections may result from deformation. Ribs are weak, feebly prorsiradiate, sweep back and strengthen on both upper and lower whorl faces; they are markedly oblique and reach their maximum strength on the outer whorl face. Every fourth to sixth rib is strengthened, forming a pronounced flare; these are conspicuous on the lateral, ventrolateral and ventral whorls.

Dimensions. Table 15.

Remarks. This species was extensively discussed by Lewy (1983), and additional comments were provided by Klinger and Kennedy (2003) and Klinger et al. (2007). The latter authors discussed dimorphism in this species.

Occurrence. Middle Santonian to lower upper Santonian of France, middle Santonian to lower Campanian of South Africa, upper Santonian of Israel, Austria, and Mississippi, uppermost Santonian to lower Campanian of Coahuila, lower Campanian of Madagascar.

Figures

FIGURE 36. Amapondella amapondense (van Hoepen, 1921) from bed TPY50 of the Tepeyac section. A–C: CPC– 2345, D–E: CPC–2346. Scale: 50 mm.

FIGURE 37. Amapondella amapondense from bed TPY 50 of the Tepeyac section. A–E: CPC–2347. Scale: 50 mm.