Records of the Western Australian Museum 17: 417-437 (1996). 
Biostratigraphy of Devonian microvertebrates from Broken River, 
North Queensland 
Alison M. De Pomeroy 
Centre for Ecostratigraphy and Palaeobiology, School of Earth Sciences, Macquarie University, NSW 2109 
Abstract - Microvertebrate faunas from acid-leached residues from the 
Broken River region of north Queensland are dated by accompanying 
conodonts and span the interval serotinus (late Emsian) to asymmetricus 
(earliest Frasnian) zones. 
Five major Devonian fish groups are represented: agnathan (thelodont), 
acanthodian (Cheiracanthoides comptus, Nostolepis cf. costata, Nostolepis spp., 
Acanthoides sp,), chondrichthyan (Cladolepis cl. gunnelli, Ohialepis sp., 
phoebodont, indeterminate), placoderm (arthrodire, ptyctodontid), and 
osteichthyan (crossopterygian including Onychodus sp., palaeoniscoid, 
dipnoan). 
Scales of C. comptus and Cladolepis cf. gunnelli both occur in horizons as 
young as asymmetricus Zone and are therefore longer ranging than 
previously reported. The stratigraphic range of the other Broken River forms 
falls within the range reported from elsewhere. 
INTRODUCTION 
The Broken River Group of North Queensland 
crops out as two shallow marine mixed carbonate 
platforms (northern Pandanus Platform and 
southern Dosey-Craigie Platform) covering 
approximately 320 square kilometres; it comprises 
five fossiliferous formations dated by conodonts as 
ranging from mid Emsian to earliest Frasnian 
(Mawson and Talent 1989). In the south (Figure 1), 
there are two limestone formations (Lomandra and 
Dosey limestones), and three mudstone/shale/ 
siltstone units with nodular limestones (Bracteata 
Formation, Papilio Formation with associated 
Spanner Limestone Member, and Mytton 
Formation with associated Stanley Limestone 
Member); details of stratigraphy are given in the 
legend to Figure 1. Environments of deposition are 
interpreted as shallow marine (Lomandra 
Limestone, Mytton Formation), protected muddy 
shelf (Papilio Formation), deeper water muddy 
shelf (Bracteata Formation), shallow carbonate 
shelf (Dosey Limestone, Spanner Limestone), and 
carbonate shoal (Stanley Limestone) (Mawson and 
Talent 1989). 
Previous work on the Broken River Group has 
resulted in reports of both microvertebrates and 
macrovertebrates. Reported from Early Devonian 
horizons are acanthodian scales and platelets, 
including Nostolepis sp., buchanosteid and 
radotinid tesserae, onychodontid teeth and an 
endemic turiniid from the Martins Well Limestone 
(Turner 1991, 1993), dated by conodonts as pcsavis- 
sulcatus zones (Mawson cl al. 1988; Withnall and 
Jell 1988). Middle Devonian forms reported are 
more diverse: antiarchs Wurungulepis denisoni, 
represented by scales, fin bones, and articulated 
trunk armour, and skull and dermal bones of 
Nawagiaspis wadeae from Eifelian and Givetian 
horizons (Young 1990); Cheiracanthoides comptus 
scales, onychodontid teeth and palaeoniscoid 
remains from the Eifelian-Givetian Fish Hill, and a 
phoebodont tooth from the Papilio Formation 
(varcusZone) (Turnerl993); acanthodians Acanthodes 
sp., and an indeterminate ischnacanthid, 
chondrichthyan Ohioiepis sp., thelodont Turinia sp., 
placoderms cf. Pterichthyodes sp. and indeterminate 
asterolepidoid, brachythoracid and rhenanid? 
remains, dipnoan cf. Chirodipterus sp., 
onychodontid Onychodus cf. sigmoides, and 
palaeoniscoid Ligulalepis toombsi (Long and Turner 
1984); and acanthodian Machaeracanthus sp., 
placoderms Atlantidosteus sp. and a new 
brachythoracid, and an indeterminate dipterid 
(Young 1993). A 50mm-long crossopterygian lower 
dentary, as yet undescribed but probably 
Onychodus sp., was recovered in 1993 from near 
Fish Hill, from a horizon dated by associated 
conodonts as close to the costatus/australis 
boundary (De Pomeroy et al. 1994). 
For details of geology, interpreted depositional 
environment and conodont biostratigraphy, see 
Mawson and Talent (1989). 
RESULTS OF STUDY 
Twenty sections (comprising 586 samples, each 
weighing approximately 1 kg) were measured from 
the Dosey-Craigie Platform and the southernmost 
