72 
possession of a simple suture pattern. Some of these original 
members are now referred to Spathites Kummel & Decker, 1954. 
The type species, V. gamai, was regarded as part of a group 
characterized by a wide umbilicus and the possession of a single 
(umbilical) row of tubercles. Recent discussions of Vascoceras 
have been given by Wright & Kennedy (1981) and Berthou et al. 
(1985). It is commonly suggested that Paravascoceras, 
Pachyvascoceras, Paracanthoceras, Broggiiceras, 
Discovascoceras, Provascoceras and, sometimes, 
Greenhornoceras should be regarded as strict synonyms of 
Vascoceras without even subgeneric distinction (see Berthou et 
al. 1985, Kennedy, Wright & Hancock 1987, Luger & Gréschke 
1989, Kennedy, Cobban, Hancock & Hook 1989, Cobban et al. 
1989). 
The oldest known species included in Vascoceras is the 
micromorph Ammonites diartianus d’Orbigny, the type material 
of which was redescribed by Kennedy & Juignet (1977). Further 
examples were subsequently described by Wright & Kennedy 
(1981: 86, pl. 17, fig. 1; text-figs 29A—F), Forster et al. (1983: 133, 
pl. 3, figs 1-5) and Cobban et al. (1989: 47, figs 48, 88TT-AA). V. 
diartianum occurs most frequently in the Geslinianum Zone or 
equivalents but Kennedy et al. (1989: 80) reported examples in 
New Mexico from equivalents of the underlying Guerangeri 
Zone. Kennedy & Wright (1985) and Wright & Kennedy (1987) 
drew attention to the morphological similarity between V. 
diartianum and Protacanthoceras of the P. proteus Wright & 
Kennedy group (see Wright & Kennedy 1980: 95, figs 49-S1, 
57-58; 1987: 216, pl. 55, figs 4, 9, 17, 18, 21-23; text-figs 82B, 
83G, M, 84P). They believed the former to have been derived 
from the latter. Accordingly, V. diartianum would constitute the 
root stock of Vascoceras and the above-mentioned suggested 
synonyms. 
Cooper (1979) was reluctant to admit the Late Cenomanian 
age of Vascoceras and pointed to a number of differences 
between Ammonites diartianus and V. gamai, the most significant 
of which regarded their ornamentation. He proposed the genus 
Provascoceras for A. diartianus but regarded the species as 
ancestral to both Vascoceras and Paravascoceras. A. diartianus 1s 
clearly transitional between Acanthoceratinae and 
Vascoceratidae, retaining the bifid first lateral saddle of the 
former. Its ornament consists of rounded to twisted to distinctly 
bullate umbilical tubercles which may envelop practically the 
whole of the flanks and fine bundled ribbing extending across 
the venter. Relatively little is known of the inner whorls of 
topotype material of V. gamai. Choffat (1898: pl. 7, figs 3, 4; pl. 
8, fig. 4; pl. 10, fig. 2) figured a number of juveniles which show 
approximately 8 umbilical bullae and 20 coarse, regularly 
developed major and minor ribs which cross the venter (see also 
Berthou et al. 1985: 67). The umbilical tubercles may be 
persistent but the ornament generally disappears on the later 
whorls. A similar juvenile ornament has been described in 
material referred to V. gamai from Egypt (Luger & Gréschke 
1989: 378, pl. 40, figs 5, 7) and V. cf. gamai from New Mexico 
(Cobban er al. 1989: 45, figs 87W-AA, EE-RR). There are, 
however, other juveniles from Portugal with rather different 
ornamentation. V. silvanense Choffat (1898: 57, pl. 8, fig. 5; pl. 
21, fig. 9) shows massive umbilical bullae but no definite ribbing. 
Berthou et al. (1985: 68) regarded V. silvanense as a nomen 
dubium and almost certainly the inner whorls of one or another 
P.M.P. ZABORSKI 
of the Portugese species of Vascoceras. Another individual 
(Berthou ef al. 1985: 68, pl. 3, figs 4, 8, 9) displays about 10 | 
umbilical bullae intermediate in strength between those found in 
V. gamai and V. silvanense and about twice as many low ventral 
ribs mostly arising in pairs from these bullae. Berthou et al. 
(1985: 68) compared this specimen with V. adonense Choffat 
which they regarded as a synonym of V. gamai. Its ornament is 
reminiscent of that in Ammonites diartianus. Numerous juvenile 
whorls of V. woodsi are available from north-eastern Nigeria (see 
below). They show a considerable variation in ornament. | 
Although no comparable variation series is available for the 
Portugese Vascoceras, it is possible that certain V. gamai could © 
show an early ornament approaching that in Ammonites 
diartianus. Despite its transitional nature, A. diartianus is here 
regarded as belonging in Vascoceras and Provascoceras is 
therefore a synonym. 
Discovascoceras Collignon (type species Vascoceras 
( Discovascoceras ) tesselitense Collignon 1957: 125, pl. 1, figs la, 
b; by original designation) was originally proposed by Collignon 
(1957: 123) as a subgenus of Vascoceras but was later raised to 
the status of a separate genus following an amended diagnosis © 
(Collignon 1965: 179). Its essential characters were given as its 
triangular whorls, presence of three carinae on the middle 
whorls, variation in spacing and degree of indentation of the 
sutures, depth of the umbilicus, egression of the adult whorl and 
tendency for apertural constriction. Berthou er al. (1985: 75) 
regarded the holotype of D. tesselitense as an indeterminate 
Vascoceras, the species as invalid and Discovascoceras 
Collignon, 1957 as a synonym of Vascoceras. In view of its 
ventral carinae they compared the material later described as D. 
tesselitense by Collignon (1965: 181, pl. G, figs la, b) with 
Pseudotissotia Peron (see also Hirano 1983: 69-70). They 
proposed that Collignon’s second account be taken as the first 
valid one of Pseudotissotia? tesselitense. Collignon’s (1965) 
material, however, shows similarities with Nigerian forms 
intermediate between Vascoceras globosum costatum and 
Thomasites which are described below. Here both the Collignon 
1957 and 1965 descriptions are regarded as dealing with 
Vascoceras but the 1965 material could alternatively be assigned 
to Thomasites. 
Greenhornoceras Cobban & Scott (type species Vascoceras 
( Greenhornoceras ) birchbyi Cobban & Scott 1972: 85, pl. 22; pl. 
23, figs 1-13; pl. 24, figs 1-12; pl. 25; pl. 26, figs 5—8, 11, 12; pl. 27, 
figs 1-6; text-figs 43-47; by original designation) is amongst the 
stratigraphically youngest examples of Vascoceras. Cobban & 
Scott (1972: 84-85) distinguished the subgenus Greenhornoceras 
only on the basis of being more involute than V. ( Vascoceras) 
and in maintaining a square to rectangular whorl section. Its 
juvenile ornament of strong, regularly developed long and short 
ribs gives way to smooth later whorls. There is no compelling 
reason to regard Greenhornoceras as anything other than a strict 
synonym of Vascoceras. 
As mentioned above, Paravascoceras (= Paracanthoceras, 
Pachyvascoceras, Broggiiceras) is here regarded as a distinct 
genus with an origin separate from that of Vascoceras and is 
most properly included in the Acanthoceratinae. 
Figs 25-30 Vascoceras woodsi sp. nov. Figs 25-27, Pindiga Formation, unit M, Ashaka. Fig. 25a, b, paratype, C.93341, x1. Fig. 26a, b, paratype, 
C.93339, x1. Fig. 27a, b, holotype, C.93342, x1. Fig. 28a, b, Pindiga Formation, unit M, Pindiga. Paratype, C.91263, x1. Fig. 29a, b, Pindiga For- 
mation, unit N, Pindiga. Paratype, C.93351, x1. Fig. 30, Pindiga Formation, Deba Habe. Paratype, C.91257, x1. 
