Abstract
Fossil wood collected from 14 sites in the southern South Island, New Zealand was identified to family or genus level. These sites included two of Eocene age: Waihao River (Runangan to early Whaingaroan) and Pikopiko (Runangan to early Whaingaroan); one of Oligocene age: Cosy Dell Lime Pit, (Duntroonian – wood of this age has not been previously studied in New Zealand); nine of Miocene age: Lake Aviemore (uncertain), Idaburn, Roxburgh, St Bathans (all three Otaian to Lillburnian), Bennett’s Pit, Cosy Dell Coal Pit, Landslip Hill, Mataura Coal Mine and Newvale Coal Mine(these five Waitakian to Altonian); and two of Pliocene age: Gold Sandpit (uncertain) and Orepuki (Nukumaruan to Castlecliffian). The quality of wood preservation is highly variable, even within a single site. These differences in preservation types required a number of different preparation techniques to be trialled, including thin sectioning at standard orientations for wood anatomy (transverse, tangential and radial), Scanning Electron Microscope imaging and charcoalification. Thin sectioning ‘Silicified’ and ‘Calcified’ samples provided readily identifiable sections, while softer ‘Carbonised’ types provided best sections when charcoalified. Two sites in Canterbury were studied: Lake Aviemore and Waihao River. The samples identified at Lake Aviemore are all angiospermous, and related to non-New Zealand native Casuarinaceae, Myrtaceae or Picrodendraceae. The single sample found in the marine sequence at Waihao River is araucarian. Three sites in Otago were studied: Idaburn Coal Mine, Roxburgh Coal Mine, Upper Manuherikia River. At Idaburn, Cupressaceae (Libocedrus Endl.) and Podocarpaceae (Podocarpus L'Hér ex Pers.; Prumnopitys Phil.) were identified. A single sample from the Roxburgh Coal Mine was identified as either Podocarpus or Libocedrus. A sample from the Upper Manuherikia River resembles Casuarina L. Nine sites in Southland were studied, including Bennett’s Pit, Cosy Dell Coal Pit, Cosy Dell Lime Pit, Gold Sandpit, Landslip Hill, Mataura Coal Mine, Newvale Coal Mine, Orepuki-Gemstone Beach and Pikopiko. At Bennett’s Pit Libocedrus or Podocarpus was present. At the Cosy Dell Coal Pit, wood resembling Lagarostrobos Quinn and Podocarpus was present. At the Cosy Dell Lime Pit, a Podocarpus, bearing most resemblance to P. acutifolius Kirk, was identified. At the Gold Sandpit, Podocarpaceae (Phyllocladus Rich. ex Mirb.) was identified. A sample closely resembling Casuarinaceae (Gymnostoma L.A.S. Johnson) was present at Landslip Hill. This site has produced cones of this type previously. The Mataura Coal Mine, which has been studied previously, has Cupressaceae (Libocedrus) and rooted Podocarpaceae stumps up to 70 cm in diameter, while the Newvale Coal Mine has Araucariaceae, Cupressaceae and Podocarpaceae logs and branches. The younger Orepuki-Gemstone beach has Nestegis Raf., while the older Pikopiko Fossil Forest has Podocarpus or Libocedrus. Identification of samples of fossil wood provides new data that can be used to reconstruct the forest vegetation that grew in southern New Zealand during the Cenozoic.