• Due to a lack of flow-indicative sedimentary structures, the Mintaja fossil layer is thought to have been deposited in a quiescent, subaqueous environment with no or little fluvial influence, although the coarse silt grain-size and common, highly fragmented plant material suggests a shallow depth for this water body. A lack of coaly or lignitic layers within the fossil-bearing sediments indicates oxygenated conditions at the sediment–water interface, so that organic material decayed rather than being preserved, preventing any build-up of organic material. This suggests deposition in a shallow pool, as opposed to a mire or swamp. The hypothesized conditions fit well with the overall interpretation of the Cattamarra Coal Measures as a delta-plain deposit, with fine-grained sediments (such as at Mintaja) representing deposition in interdistributary bay environments (Mory, 1994).