A few Ortonella-like porostromate problematica were also present early in the reef core
. They are unattached, bulbous tubular organisms (Fig.
Using data from geomorphic, sedimentological, biological, and dating information from fossil reef cores
at 16 sites at Cairns and Mackay, the study covered the period from before the last glacial maximum, the last time period during the last glacial period when ice sheets were at their greatest extension, about 20,000 years ago, when sea levels were 118 metres below current levels.
To understand the evolution of the reef system over 30 millennia, the team collected geomorphological, sedimentological, biological and geochronological information from 16 fossil reef cores
across North Queensland, Australia.
The Earth is currently in a high-seas period, McKenzie says, and according to the geologic record and the reef cores
, the oceans are due to fall again, though not for at least another several thousand years.