74 
Vascoceras woodsi sp. nov. Bigs 911, 25—32 
1957. Vascoceras sp. juv. Barber: 27, pl. 6, figs 2, 4, 7; pl. 27, 
figs 10-15. 
21965 Vascoceras gamai Choffat; Collignon: 185, figs 5—7. 
1989  Plesiovascoceras aff. gr. thomi (Reeside) ou sp. nov. 
Meister: 11, pl. 4, figs 2, 3, 5; text-fig. 8. 
1989  Paravascoceras gr. evolutum Schneegans; Meister: 14 
(pars), pl. 5, fig. 4 (only); text-fig. 10. 
1990a_ Vascoceras gr. evolutum (Schneegans); Zaborski: 7. 
1990a_ Vascoceras sp. Zaborski: figs 9, 10. 
1990a_ Vascoceras sp. juv. Zaborski: figs 16-18, 20, 21. 
1992 Vascoceras gr. thomi (Reeside) ou  evolutum 
(Schneegans); Courville: pl. 5, fig. 1. 
1993 Vascoceras sp. nov. aff. gamai Choffat; Zaborski: 365. 
1995 Vascoceras sp. nov. aff. gamai Choffat; Zaborski: 54, 
5): 
HOLOTYPE. C.93342 (Fig. 27), Pindiga Formation, unit M, 
Ashaka. 
PARATYPES. Thirty-four specimens, C.93339, ©C.93341, 
C.93343-4, C.93543, Pindiga Formation, unit M, Ashaka; 
C.91262-70, Pindiga Formation, unit M, Pindiga; C.91224-5, 
C.91311, C€.91313-4, C.93351, Pindiga Formation, unit N, 
Pindiga; C.91256-61, C.93355, C.93596a-f, C.93597, Pindiga 
Formation, Deba Habe. 
DIMENSIONS. 
D Wb Wh U 
€.93597 94 - 31 (33) 39 (41.5) 
C.93351 60 34 (57) 22 (37) DKS) 
C.91264 53 32 (60) 20 (38) 18 (34) 
€.93355 Sy) 31 (60) 18 (35) 20 (38.5) 
C.91256 50 29 (58) 20 (40) 17 (34) 
C.91263 40 25 (62) 15 (37.5) NSIS 2E5)) 
C.91257 39 24 (61.5) 16 (41) 11 (28) 
C.91262 34 20 (59) 13 (38) 10 (29) 
DERIVATION OF NAME. After the late H. Woods who first 
described ammonites from north-eastern Nigeria. 
DIAGNOSIS. Evolute Vascoceras with whorls broader than high. 
Middle whorls with rounded or more normally highly bullate 
umbilical tubercles fusing with inner ventro-lateral bullae to 
cover the flanks. Adult body-chamber smooth or with umbilical 
tubercles and/or relatively weak ventral ribbing. 
DESCRIPTION. The shell is evolute, the umbilicus widening 
during growth from about one-third to 40% or more of the 
overall diameter. The maximum diameter attained is about 120 
mm, when the body-chamber makes up two-thirds of the final 
whorl. In all but the very earliest growth stages the whorls are 
distinctly broader than high. 
Two nuclei are available. In C.93596f the whorls are initially 
smooth and tubular with a broadly rounded venter. At a 
diameter of 3 mm broad bullate swellings enveloping the inner 
half of the flanks appear and give rise to low ribs which cross the 
Fig. 32 
€.93514, x1. 
Figs 36-37 Pseudovascoceras nigeriense (Woods). Pindiga Formation, unit O, Ashaka. Fig. 36a, b, C.93499, x1. Fig. 37a, b, C.93494d, x1. 
Vascoceras woodsi sp. nov. Pindiga Formation, Deba Habe. Paratype, C.93597, x1. 
Figs 33-35 Vascoceras bullatum Schneegans. Pindiga Formation, unit O, Ashaka. Fig. 33a, b, C.93512, x1. Fig. 34a, b, C.93516a, x1. Fig. 35a, b, 
P.M.P. ZABORSKI 
l 1 cm j 
Fig. 31 Suture in Vascoceras woodsi sp. nov. Holotype, C.93342. 
Pindiga Formation, unit M, Ashaka. 
venter. The suture shows a direct transition from an entire to an ~ 
evenly frilled E/L; this saddle is never bifid. In C.93596e about 10 
umbilical bullae have developed by a diameter of 6 mm but the 
venter lacks ribbing. 
In the succeeding growth stages (Figs 9, 10) the characteristic 
ornament consists of 8-10 lateral bullae in each whorl, upon 
which discrete umbilical and inner ventrolateral swellings can 
sometimes be made out. Most of the bullae give rise to a narrow 
rounded rib which crosses the venter and bears outer 
ventrolateral tubercles. No definite siphonal tubercles can be | 
made out. There may be a single ventral rib bearing only outer 
ventrolateral tubercles alternating with each major rib. In other | 
specimens no well-developed ribbing exists. In all cases sharply 
defined ribbing disappears at diameters of 10-15 mm though the | 
lateral bullae persist. At these diameters the venter becomes | 
flattened and the whorls increasingly depressed. 
At diameters of 20-60 mm the main ornament consists of 6-8 | 
umbilical tubercles in each whorl which are of variable shape | 
and strength. They are commonly highly bullate but may be | 
rounded, clavate or paired in nature. At first the more bullate | 
types may partially fuse with bullate inner ventrolateral swellings | 
but the latter features quickly fade during growth. Broad, vague 
fold-like ribs which cross the venter may issue from the umbilical 
tubercles or the venter may be smooth. Such ribs, however, rarely 
persist beyond diameters of 40 mm. 
Umbilical tubercles may persist onto the adult body-chamber 
which is frequently compressed. Ventral ribbing may develop | 
here taking the form of irregular closely-spaced plicae at one | 
extreme and moderately strong fairly evenly-spaced ribs at the » 
other. 
The suture (Fig. 31) is of the typically simple type found in 
Vascoceras. 
REMARKS. Ina previous account (Zaborski 1990a: 5) doubt was | 
expressed about whether a number of juvenile Vascoceras | 
collected from Deba Habe and Pindiga were conspecific. V. 
woodsi has been found at these two localities and at Ashaka. At | 
Pindiga adult specimens are not found, only the middle septate | 
whorls being found in units L, M and N. At Ashaka the species is 
abundant in units K and, especially, M but the material consists 
almost entirely of poorly preserved adult body-chambers. At 
Deba Habe, however, specimens representing all growth stages | 
occur ina 10 cm limestone less than 1 m below the level at which } 
Vascoceras globosum costatum and Pseudovascoceras nigeriense 
appear. Occasional juveniles from Ashaka fit comfortably within 
the morphological range exhibited by the Pindiga and Deba 
Habe material. There is little doubt that all these specimens are 
conspecific. 
| 
