Records of the Western Australian Museum 18: 219-222 (1996). 
Short communication 
First record of an Early Cretaceous theropod dinosaur bone 
from Western Australia 
John A. Long 1 and Arthur R.I. Cruickshank 2 
1 Department of Earth and Planetary Sciences, Western Australian Museum, Francis Street, 
Perth, Western Australia, 6000, Australia 
2 Earth Sciences Section, Leicestershire Museums, Arts and Records Service, The Rowans, 
College Street, Leicester LE2 OJJ, U.K. 
To date the only records of dinosaurs from 
Western Australia have been one possible theropod 
bone from the Late Cretaceous (Maastrichtian) 
Miria Formation, south of the Exmouth Gulf, one 
theropod pedal phalange from the Late Cretaceous 
(?Turonian-Cenomanian) Molecap Greensand, and 
a caudal vertebra from a possible sauropod from 
the Middle Jurassic Colalura Sandstone of the 
Geraldton region (Long 1992, 1995). The only 
record of dinosaurs from Early Cretaceous 
sediments in Western Australia is from footprints 
preserved in the Berriasian-Valanginian Broome 
Sandstone exposed in the Broome region and 
Dampier Peninsula. This assemblage of trackways 
from Broome indicates a great diversity of 
dinosaurs existed in Western Australia at this time, 
ranging from theropods (Colbert and Merrilees 
1967), sauropods (Thulborn et al. 1994), bipedal 
ornithischians and a possible stegosaur (Long 
1993), but no skeletal remains have been recovered. 
Here we report the first occurrence of a dinosaur 
bone of Early Cretaceous age from Western 
Australia. 
The specimen was found by one of us (JL) about 
4 metres way from where a partial skeleton of a 
new species of the pliosaur Leptocleidus was found 
(Cruickshank and Long in press), from the 
Hauterivian-Barremian Birdrong Sandstone, 
exposed to the north of Kalbarri. It was lying on 
the surface scree weathered out from near the top 
metre of the Birdrong Sandstone, preserved in 
exactly the same manner as the pliosaur bones 
recovered from that unit. To date many such bones 
of pliosaurs and some ichthyosaurs have been 
found on outcrops of the Birdrong Sandstone, all 
appear to be coming out of the top metre or so of 
the unit. The specimen described herein was found 
in three pieces lying in close association, only a few 
centimetres apart, which were glued together to 
show its characteristic vertebral shape. 
Description of the specimen 
The specimen (WAM 96.5.1, Fig. 1) is a mid 
caudal vertebra. It differs from the pliosaurid 
vertebrae commonly found in the Birdong 
Sandstone by its much longer rostrocaudal length, 
narrower centrum, and its short flattened 
transverse processes (Fig. 1C, tr.p), and lack of 
subcentral foramina. The dorsal surface shows the 
traces of where the posterior zygapophyses were 
developed (Fig. 1C, po). The bone lacks tire neural 
arch and is missing part of the posterior centrum 
as well as the distal face of the centrum. The 
anterior face of the centrum is flat, a characteristic 
of theropod mid caudal vertebrae, and is much 
larger than the estimated size of the posterior face 
of the centrum. In this respect it differs from the 
caudal vertebrae in hypsilophodontids and basal 
iguanodontians in general (Galton 1974, Coria and 
Salgado 1996). Sauropods tend to have long tails 
and so the mid-distal caudal vertebrae are mostly 
elongated, amphicoelous, with approximately 
equal anterior and posterior centrum faces 
(McIntosh 1990), unlike the Birdrong specimen. 
Most thyreophorans, or the armoured ankylosaurs 
and stegosaurs, have specialised tails bearing 
enlarged clubs, spines or heavy dermal ossicles, 
and thus the mid caudal vertebrae are more robust 
with strongly overlapping postzygapophyses 
(Coombs et ah 1990; Coombs and Maryanska 1990). 
By comparison with the tail vertebrae of 
Allosaurus fragilis (Madsen 1976) and direct 
observation of other theropod dinosaur skeletons 
(e.g., Gorgosaurus libralus, W.A. Museum cast; 
Tarbosaurus bataar, Palaeontological Institut, 
Moscow 551- 4/49) it is most likely from a 
theropod. It compares very closely in overall 
proportions with the 37th-40th caudal vertebrae of 
Allosaurus fragilis (Madsen 1976, pi. 35 F,G,) but is 
about half the size, suggesting that the Birdrong 
theropod may have been in the order of 5 m 
maximum length. 
Discussion 
Early Cretaceous theropods thus far recovered 
from Australia mostly come from the Albian- 
Aptian Otway and Strzelecki Groups of Victoria. 
They include the allosaurid Allosaurus sp. (Molnar 
