De 
_BARYONYX WALKERI 
INTRODUCTION 
Discovery 
The discovery of Baryonyx was a major event in the history of 
British dinosaur palaeontology (Milner & Croucher 1987). Extant 
faunas of large terrestrial vertebrates invariably include only a small 
proportion of carnivores, these being at the apex of the food pyra- 
mid, and fossil faunas were probably no different. Dinosaur discovery 
in England goes back more than 300 years (Plot 1677) and includes 
several finds of a few bones or teeth of carnivores. Until 1983, 
10wever, the only significant find of a carnivorous dinosaur had been 
he partial skeleton of Eustreptospondylus oxoniensis (originally 
dlaced in the genus Megalosaurus), found in Oxfordshire in 1871 
ind now in the Oxford University Museum. Since the discovery of 
3aryonyx, the partial skeleton of an allosauroid has been described 
rom the Wessex Formation (Wealden) of the Isle of Wight (Hutt, 
Martill & Barker 1996). 
| Details of the discovery of Baryonyx were published by Milner & 
-roucher (1987). The enlarged ungual phalanx, the famous ‘Claw’ 
originally missing the tip), a second smaller, less complete ungual 
ihalanx and an incomplete haemapophysis, were found on 7 Janu- 
ry 1983 by Mr William J. Walker at the Ockley Brick Company’s 
jlaypit near Ockley, Surrey, and a week later he found the missing tip 
f the claw. After examining this material at the British Museum 
Natural History), we visited the site on 7 February and found large 
ark-brown bones from the pelvis and hind-limb, lying just beneath 
1e surface of the clay. The physical conditions in the claypit 
revented us from collecting the skeleton until the period 25 May to 
0 June 1983, when a team of eight from the Department of 
eo ey and a number of volunteers excavated two tonnes of 
vatrix containing bone. 
| All the remains were found within an oval excavation measuring 
oproximately 5 metres by 2 metres (Fig. 49). Most were encased in 
ia of sideritic siltstone, which had been deposited around the 
i but some lay unprotected in soft clay. The skeleton was 
rgely disarticulated and the elements gently scattered, but most of 
em were still lying approximately in their skeletal position, with 
€ animal’s skull at one end and its tail at the other. Some nodules 
ere lifted untreated, some were encased in plaster of Paris and 
hers in expanded polyurethane foam. 
reparation 
‘eparation of the material was especially difficult because of the 
wdness of the siltstone matrix, made more intractable by the 
jesence of siderite. A few pieces were subjected experimentally to 
(emical treatment with thioglycollic acid (which dissolves iron 
Its but has little or no action on siltstone and other non-ferrous 
icks), but it had practically no effect, so most of the matrix had to 
removed by mechanical methods. Some field cocoons, the bulk of 
: tock and the underlying clay were removed rapidly with an 
iustrial shot blaster, a Vacu-Blast Nova 150PB, using plastic shot 
‘the abrasive; as far as is known (R. Croucher and W. Lindsay, pers. 
(mms) this is the first recorded instance of the use of such equip- 
Int for preparing fossils. Rock was also removed with hand tools 
éd with tools powered by compressed air, including diamond- 
Gted circular saws and chisels. For more delicate work close to the 
Ls surface, finely pointed engravers were used under binocular 
toscopes. Other details of the laboratory work on Baryonyx were 
i by Milner & Croucher (1987). 
SYSTEMATIC DESCRIPTION 
Suborder THEROPODA Marsh, 1881 
Superfamily SPINOSAUROIDEA Stromer, 1915 
Family BARYONYCHIDAE Charig & Milner, 1986 
TYPE-GENUS. Baryonyx Charig & Milner, 1986. 
DERIVATION OF NAME. From Greek Bapuc, heavy; ovv6, claw. 
DIAGNOsIs. As for genus Baryonyx. 
Genus BARYONYX Charig & Milner, 1986 
TYPE-GENUS. B. walkeri Charig & Milner, 1986; Early Creta- 
ceous, Surrey, England. 
DIAGNOSIS. Monotypic genus, as for species B. walkeri. 
Baryonyx walkeri Charig & Milner, 1986 
DERIVATION OF NAME. 
the original claw-bone. 
For Mr William J. Walker, who discovered 
HOLOTYPE. Natural History Museum, London: Department of 
Palaeontology, BMNH R9951. 
MATERIAL. The’holotype alone; consisting of conjoined premax- 
illae, conjoined vomers, anterior part of left maxilla, conjoined 
nasals, left lacrimal, left prefrontal, left postorbital, anterior end of 
braincase (right frontal, right parietal, right orbitosphenoid, right 
laterosphenoid), posterior end of braincase together with occiput 
(both prootics, both opisthotics, basisphenoid, supraoccipital, both 
exoccipitals, basioccipital), left jugal, both quadrates; both dentaries, 
both splenials, right surangular, both angulars, right coronoid: some 
upper teeth in situ and many isolated teeth of unknown position in 
the jaws; axis and 4 further cervical vertebrae, 12 dorsals, 3 or 4 
basal caudals, 3 more distal caudals; one axial rib, three other 
cervical ribs, many dorsal ribs, abdominal ribs, 5 haemapophyses, 
sternum; both scapulae, both coracoids; both humeri, left radius, left 
ulna, left pollex with huge ungual, left digit II (complete) or digit 
Ill, ,, other isolated phalanges of both sides; right ilium, both 
pubes, left ischium; proximal end of left femur and distal end of 
right, right fibula, right calcaneum, metatarsal fragments, | pedal 
ungual. 
LOCALITY. Smokejack’s Brickworks (Ockley Building Products 
Limited, formerly Ockley Brick Company Limited), Wallis Wood, 
Ockley, near Dorking, Surrey, England. A little below the top of the 
south-east face, nearest to the works buildings. National Grid refer- 
ence TQ 113373. 
HORIZON. Lower Cretaceous, Wealden Series, Upper Weald Clay; 
zone of Cypridea clavata, near the base of the Barremian; about 7 m 
below the base of BGS Bed Sc (See Ross & Cook 1995). 
DIAGNOSIS. Prenarial region of snout extended into extremely 
narrow rostrum with spatulate, horizontal expansion at end (‘term- 
inal rosette’); snout slightly downturned in lateral view, jaws with 
sigmoidal margins. Long, low external naris far back on side of 
