UPPER CRETACEOUS AMMONITE 
Paravascoceras cauvini (Chudeau, 1909) 
1909 
1921 
1933 
1935 
1935 
1935 
1935 
1943 
1943 
1943 
1943 
1957 
1957 
11957 
71965 
1969 
1969 
1975 
1981 
1992 
1992 
Figs 2-8 
Vascoceras cauvini Chudeau: 68, pls 1, 2; pl. 3, figs 1, 2. 
Thomasites cauvini (Chudeau) Chudeau: 463, fig. 1. 
Vascoceras cauvini Chudeau; Furon: 268, pl. 9, fig. 9. 
Vascoceras (Paracanthoceras) Chevalieri Furon: 59, 
pl. 4, figs la, b. 
Vascoceras ( Paravascoceras ) Cauvini Chudeau Furon: 
60, pl. 5, figs la, b. 
Vascoceras ( Paravascoceras) Chudeaui Furon: 61, pl. 
4, fig. 2. 
Vascoceras (Paravascoceras) Cauvini Chudeau nov. 
var. semiglabra Furon: 61, pl. 4, fig. 3. 
Paravascoceras cauvini (Chudeau); Schneegans: 128, 
pl. 4, fig. 2. 
Paravascoceras cauvini var. evoluta Schneegans: 130, 
pl. 8, fig. 2. 
Paravascoceras cauvini vat. inflata Schneegans: 131. 
Paravascoceras chevalieri Furon Schneegans: 132, pl. 
4, fig. 7. 
Vascoceras bulbosum (Reyment) Barber: 19, pl. 6, figs 
6, 8; pl. 27, figs 1-6. 
Vascoceras depressum Barber: 19, pl. 6, fig. 5; pl. 27, 
figs 7-9. 
Paravascoceras aff. cauvini (Chudeau); Barber: 37, pl. 
14, figs 2, 3; pl. 32, figs 8, 9. 
Paravascoceras aff. cauvini (Chudeau); Collignon: 183. 
Paravascoceras cauvini (Chudeau); Freund & Raab: 
20, pl. 3, figs 1-3; text-figs 5a, b. 
Paravascoceras tavense (Faraud) Freund & Raab: 23, 
pl. 2, fig. 9, text-figs 5e—g. 
Paravascoceras cauvini (Chudeau); Schobel: 119, pl. 4, 
fig. 3; pl. 5, figs 1-4. 
Paravascoceras cauvini (Chudeau); Collignon & 
Roman (in Amard, Collignon & Roman): 51, pl. 3, fig. 
o) 
Paravascoceras_ chevalieri (Furon); Collignon & 
Roman (in Amard, Collignon & Roman): 52, pl. 6, figs 
il, 2 
Nigericeras barcoicense (Choffat) Collignon & Roman 
(in Amard, Collignon & Roman): 54, pl. 4, figs 16a, b. 
Vascoceras cauvini Chudeau; Luger & Gréschke: 374, 
pl. 40, figs 3, 6, 8, 9; pl. 41, figs 1-4; pl. 42, fig. 1; 
text-figs 6G, H, 8C. 
Nigericeras gadeni (Chudeau) /amberti Schneegans; 
Meister: 10, pl. 3, figs 13; text-fig. 6. 
Nigericeras jacqueti Schneegans; Meister: 11, pl. 2, figs 
3, 4; pl. 4, fig. 1; text-fig. 7. 
Paravascoceras aff. nigeriense? (Woods) Meister: 16, 
pl. 5, fig. 3. 
Vascoceras cauvini Chudeau; Zaborski: figs 8, 12—15. 
Vascoceras bulbosum (Reyment); Zaborski: fig. 11. 
Vascoceras (Paravascoceras) cauvini (Chudeau); 
Meister, Alzouma, Lang & Mathey: 71, pl. 4, fig. 6; pl. 
5, fig. 1, pl. 6, fig. 2. 
Vascoceras  (Paravascoceras) cauvini forme lisse 
Meister, Alzouma, Lang & Mathey: 72, pl. 5, fig. 2; pl. 
6, figs 1, 3. 
Vascoceras ( Paravascoceras) cauvini forme comprimée 
Meister, Alzouma, Lang & Mathey: 72, pl. 5, fig. 3; pl. 
6, fig. 4. 
Vascoceras gr. cauvini Chudeau; Courville: pl. 4, figs 
1-3. 
65 
MATERIAL AND OCCURRENCE. Thirty-six specimens, C.91304, 
Pindiga Formation, unit E, Ashaka; C.93556a, b, C.93557-9, 
C.93932, Pindiga Formation, unit F, Ashaka; C.93336-8, 
Pindiga Formation, unit K, Ashaka; C.91271-4, C.93304, 
C.93313, C.93517-8, Pindiga Formation, unit O, Ashaka; 
C.91278-84, C.93540-2, C.93933, Pindiga Formation, unit H, 
Pindiga; C.91285-9, C.93539, Pindiga Formation, unit J, 
Pindiga; C.91312, Pindiga Formation, unit N, Pindiga. The 
species has a known stratigraphical range from unit E (upper 
half) to unit O at Ashaka and from unit G to unit N at Pindiga. 
DIMENSIONS. See Fig. 12. 
REMARKS. In north-eastern Nigeria Paravascoceras cauvini 
includes forms showing whorls slightly to distinctly higher than 
broad, with rounded to slightly flattened venters and an 
umbilicus representing 16-29% of the total diameter. The 
species has a relatively long stratigraphical range here but 
successive assemblages show some variation. 
Material from unit F at Ashaka reaches a maximum diameter 
of some 100 mm. The adult whorls are smooth or with weak, 
irregular, crease-like ventral ribbing. The inner whorls, however, 
may show alternating long and short ribs (Fig. 5). The long ribs 
arise at umbilical tubercles. All ribs bear vague ventrolateral 
swellings but there are no siphonal tubercles. Umbilical tubercles 
or bulges may persist into the middle growth stages. This 
umbilical ornament is especially pronounced in certain 
specimens collected from the equivalent horizon (unit H) at 
Pindiga. 
Material from unit K at Ashaka is the oldest found to show 
the strong ventral adult ribbing which characterizes the species 
(Fig. 3; Meister 1989: pl. 3, fig. 1). 
Material from unit O can be regarded as fully typical of P 
cauvini. The inner whorls (Fig. 6) are completely smooth. This is 
usually the case with the middle growth stages also but rare 
individuals show bullate to clavate umbilical tubercles. Even less 
frequently there are broad, low, ventrolateral swellings but such 
features disappear by a diameter of 45 mm. Ventral ribbing is 
commonly displayed in the later growth stages (see Zaborski 
1990a: fig. 14) but this ornament appears at a diameter varying 
from 60 mm to over 100 mm and is sometimes lacking 
altogether. Adults reach a maximum diameter of over 160 mm. 
In general whorl proportions P. cauvini is a very close match 
for Nigericeras gadeni (Chudeau). The middle and adult whorls 
of the two may be difficult to distinguish unless sutures are 
visible; N. gadeni has square saddles, a narrow L and a distinctly 
bifid E/L, P cauvini has more rounded and evenly frilled saddles. 
The material from Ashaka referred to Nigericeras by Meister 
(1989) in fact belongs in P. cauvini. The early whorls of N. gadeni 
are distinct, showing a typically acanthoceratine ornament with 
long and short ribs and seven rows of tubercles (see Schneegans 
1943, Zaborski 1990a, Meister et al. 1992). Vestiges of a similar 
ornament, but without siphonal tubercles however, occur in 
early P. cauvini from unit F at Ashaka. The middle whorls of 
specimens from unit H at Pindiga sometimes show the strong 
bulge-like umbilical tubercles that are common at the same 
growth stage in N. gadeni. Meister et al. (1992: 70) and Courville 
(1992: 415) have also drawn attention to similarities between the 
juvenile ornament and in some cases suture pattern of P. cauvini 
and Nigericeras. 
Nigericeras gadeni characterizes the basal ammonite-bearing 
beds in north-eastern Nigeria, occurring in unit D at Ashaka 
and unit A at Pindiga. It therefore predates P cauvini. It is 
probable that P cauviniis derived from N. gadeni by a progressive 
