116 
la 
Fig. 1 Hylaeosaurus armatus Mantell. Right femur, distal end; BMNH 
R12555; la, posterior view, x 0.7; 1b, distal view (note the ‘step’ medial 
to the medial condyle), x 0.8. 
Polacanthus is a junior synonym of Hylaeosaurus. However, these 
authors claimed that no homologous elements are present in the 
holotype material of Hylaeosaurus and Polacanthus so the proposed 
synonymy was based largely on the similar geographical and 
stratigraphical distributions of these genera. In contrast, Blows 
(1987) suggested that the two genera are stratigraphically distinct, 
with Hylaeosaurus originating from the Hastings Beds (Valanginian) 
of East Sussex, whilst Polacanthus remains have been recovered 
from the Wessex Formation (Barremian) in the Isle of Wight. He also 
suggested that the arrangement of the dermal armour differs be- 
tween the two genera. 
Recently it has been proposed that the North American nodosaur 
Hoplitosaurus is a junior synonym of Polacanthus (Pereda- 
Suberbiola 1991, 1993). A specific separation, based on femoral 
characters, is retained to distinguish the British form (P. foxii) from 
the North American form (PR marshi Lucas, 1901). If these two 
genera are genuinely synonymous then a number of elements re- 
ferred to P. (=Hoplitosaurus) marshi that were previously unknown 
in the holotype of P. foxii (e.g. humerus and scapula) can be used for 
comparison with Hylaeosaurus. Comparisons of the pectoral girdle, 
forelimb, hindlimb and dermal armour led Pereda-Suberbiola (1991, 
1993) to the conclusion that Hylaeosaurus and Polacanthus were 
distinct genera. 
If BMNH R604k does belong to Hylaeosaurus, this would pro- 
vide another point of comparison between these two genera. The 
P.M. BARRETT 
characters listed above suggest that Polacanthus and Hylaeosaurus | 
can be distinguished on femoral characters, adding weight to the 
arguments of Blows (1987) and Pereda-Suberbiola (1993). This | 
specimen has been re-registered as BMNH R12555 in order to avoid 
confusion with other specimens allotted to BMNH R604, which 
contains a variety of other specimens from the same locality includ- 
ing [guanodon remains (Lydekker 1888). 
ORNITHOPODA Marsh 1881 
Family DRYOSAURIDAE Milner & Norman 1984 
Genus VALDOSAURUS Galton 1977 
TYPE SPECIES. Dryosaurus canaliculatus Galton 1975; Lower 
Cretaceous (Valanginian—Barremian), West Sussex and Isle of Wight, 
southern England. 
Valdosaurus canaliculatus (Galton 1975) Fig. 2 
1975 Dryosaurus? canaliculatus Galton: 747. 
1977. Valdosaurus canaliculatus (Galton); Galton: 231. 
1982 Valdosaurus canaliculatus (Galton); Galton & Taquet: 147. 
2b 
Fig. 2 Valdosaurus canaliculatus (Galton). Left femur, proximal end, 
BMNH R12440; note the deep cleft and wide separation between the 
lesser and greater trochanters. 2a, posteromedial view; 2b, proximal 
view; x |. 
