Eubaculites latecarinatus ( Brunnschweiler, 1966 )

Witts, James D., Landman, Neil H., Garb, Matthew P., Irizarry, Kayla M., Larina, Ekaterina, Thibault, Nicolas, Razmjooei, Mohammad J., Yancey, Thomas E. & Myers, Corinne E., 2021, Cephalopods from the Cretaceous-Paleogene (K-Pg) boundary interval on the Brazos River, Texas, and extinction of the ammonites, American Museum Novitates 2021 (3964), pp. 1-52 : 28-29

Eubaculites latecarinatus ( Brunnschweiler, 1966)

Figure 10L, M

Eubaculites otacodensis (Stoliczka) . Spath, 1940: 49 (pars), text-fig. 1c.

Giralites latecarinatus Brunnschweiler, 1966: 33 , pl. 3, figs. 13, 14; pl. 4, figs. 1–5; text-figs. 17, 18.

Giralites quadrisulcatus Brunnschweiler, 1966: 35 , pl. 4, figs. 11–14; text-fig. 20.

Eubaculites ambindensis Collignon, 1971: 18 , pl. 646, fig. 2393.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Klinger, 1976: 91, pl. 40, fig. 1; pl. 41, fig. 3; pl. 42, figs. 2 , 6; pl. 43, figs. 3, 4; text-figs. 11d, e.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Klinger and Kennedy in Klinger et al., 1980: 296, figs. 2 a–c, 3a–d, 4a–c, 5d.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Henderson et al., 1992: 159, figs. 22L–N, 23N–P.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Klinger and Kennedy, 1993: 238, figs. 26A, 39– 41, 42B, C, 43–49, 50A, 53A.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Kennedy et al., 1997: 20, figs. 15A–D, K, L, 16G, H, 19.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Klinger and Kennedy, 2001: 234.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Klinger et al., 2001: 287, pl. 10, figs. 4–9; text fig. 6.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Landman et al., 2004a: 34, figs. 13g–j, 14B.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Landman et al., 2004b: 63, figs. 30C, D, 31, 32.

Eubaculites latecarinatus ( Brunnschweiler, 1966) . Landman et al., 2007a: 72, figs. 36–38.

TYPE: The holotype, by original designation, is that of Brunnschweiler (1966: pl. 4, figs. 2–4 ) from the lower Maastrichtian nodule bed at the top of the Korojong Calcarenite, Carnarvon Basin , Western Australia .

MATERIAL: Two poorly preserved specimens ( UNM 15493, UNM 15527) from the second unit (ejecta-spherule-rich coarse sandstone) of the K-Pg event deposit at the base of the Kincaid Formation, AMNH loc. 3620, Falls County, Texas.

DESCRIPTION: Although poorly preserved, both UNM 15493 and 15527 are three-dimensional. UNM 15493 is a wholly septate fragment 34.6 mm long, with a whorl height of 12.6 and 13.0 mm at the adapical and adoral ends, respectively. UNM 15527 is also a wholly septate fragment 11.3 mm long, with a whorl height of 13.4 and 13.6 mm at the adapical and adoral ends, respectively. Both specimens are smooth with a tabulate venter and lack any signs of ornament.

REMARKS: The smooth flanks, tabulate venter, and lack of ornament in both these specimens distinguish them from E. carinatus .

OCCURRENCE: This species is represented by only two specimens in the K-Pg event deposit at the base of the Kincaid Formation, Falls River, Texas. It is not recorded in the Corsicana Formation. E. latecarinatus is reported from several sites in New Jersey: the upper part of the New Egypt Formation and as reworked material at the base of the Hornerstown Formation, near Eatontown, northeastern Monmouth County; the top of the New Egypt Formation in the Crosswicks Creek Basin, southwestern Monmouth County; and the top of the Tinton Formation and as reworked material at the base of the Hornerstown Formation near Freehold, central Monmouth County (summarized in Landman et al., 2007a). It is also known from the Severn Formation, Prince Georges and Kent counties, Maryland ( Kennedy et al., 1997; Landman et al., 2004a). Additional specimens have been identified (but not illustrated) at the type section of the Owl Creek Formation in Tippah County, Mississippi ( Landman et al., 2015; Sessa et al., 2015). Klinger and Kennedy (2001) reported this species from the Maastrichtian offshore Alphard Group of Zululand, South Africa, south India, Madagascar, and Western Australia.

Lower jaws of Eubaculites

Figure 11A–D

MATERIAL: Four isolated specimens (AMNH 63310, 108281, 108287, and 135059) from the top 1 m of the Corsicana Formation at AMNH locs. 3620 and 3968.

DESCRIPTION: AMNH 63310 is the best-preserved specimen (fig. 11A). It is 18.1 mm long and 6.0 mm wide, yielding a length:width ratio of 3.0. It consists of a single calcitic valve (aptychus) exposed on the dorsal side. It is semilunate in shape with a broadly rounded lateral margin and a more sharply rounded posterior margin. The symphysal edge is straight and bordered by a flange. It is covered with fine lines that parallel the lateral and posterior margins. AMNH 108287 is 6.2 mm long and 2.3 mm wide, yielding a length:width ratio of 2.7. It also consists of a single calcitic valve (aptychus) exposed on the dorsal side. However, it retains traces of the black organic layer on the inside surface of the valve. AMNH 108281 and 135059 are less complete; they consist of single valves (aptychi) with traces of black material.

REMARKS Based on comparisons with the lower jaws of baculitid ammonites described in Landman et al. (2007b) and Kruta et al. (2011), these specimens can be attributed to Eubaculites .

Figures

FIGURE 2.

FIGURE 11.