Baculites taylorensis Adkins, 1929

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 : 48

Baculites taylorensis Adkins, 1929

Figure 38A–B, G–H , Table 16

1929 Baculites taylorensis Adkins , p. 204, plate 5, figures 9-11

1993a Baculites taylorensis Adkins ; Kenney and Cobban, p. 93, figures 10.1-9, 10.11-12, 10.16, 10.18-19, 11.1-2 ( Kennedy and Cobban, 1993b)

1993b Baculites taylorensis Adkins ; Kennedy and Cobban, p. 143, plate 6, figures 1-9, plate 7, figures 1-6, 10-13; text-figure 8b, d ( Kennedy and Cobban, 1993c)

1994 Baculites taylorensis Adkins ; Cobban and Kennedy, p. D6, plate 3, figures 5- 19; text-figure 7 ( Cobban and Kennedy, 1994)

2001 Baculites taylorensis Adkins ; Kennedy and Cobban, p. 25, plate 6, figures 8-9 ( Kennedy and Cobban, 2001) (with synonymy)

2013 Baculites taylorensis Adkins, 1929 ; Ifrim et al., p. 234, figure 5b-f, figure 6f-y, figure 7a-l, figure 8a-k, figure 9a-l

Type. The holotype is TMM 21014 by monotypy .

This specimen is from the basal Pecan Gap Chalk,

Travis County, Texas .

Material. Two specimens, CPC –2198 and –2199 ,

both internal moulds, from beds TPY64 and 77,

respectively.

Description. Shell substraight with a low expansion rate. Whorl section is stout and ovate, with a widely-rounded dorsum, dorsolaterally parallel and ventrolaterally convergent flanks which terminate in a moderately narrow rounded venter. Rib index is 1 to 0.5. These nodes arise at the dorsolateral shoulder and increase in size on the dorsal third to half of the flank; they are rounded and weak in CPC–2183 and stronger in CPC–2199. Ribs and nodes fade markedly on both the dorsum and the ventral portion of the flank.

Dimensions. Table 16.

Remarks. The two specimens and their ornamentation match the abundant specimens described from Arkansas, Texas and Coahuila.

Occurrence. Lower-upper Campanian of the northern and north-western Gulf coast. The FAD of the species marks the base for an uppermost lower Campanian biozone in this region.

Figures

FIGURE 38. Baculites from the Tepeyac section. A–B, G–H: Baculites taylorensis, A–B: CPC–2198, bed TPY64; G–H: CPC–2199 before extraction from bed TPY77; C–F, I–L: Baculites haresi, C–F: CPC–2607, bed TPY52; I–L: CPC2606, bed TPY77. Scale: 50 mm.