Abstract Detail



Paleobotany

Geary, Ian [1], Beever, Jessica [2], Hayward, Bruce [3], Lee, Daphne [1], Conran, John [4], Lord, Janice [5].

New Late Pliocene floras from northern New Zealand: The last remnants of warm-indicative taxa?

A suite of Late Pliocene (Waipipian, 3.7–3.0 Ma) terrestrial fossils have been discovered from sites near Auckland, northern New Zealand. Fluvial, estuarine and near-shore sediments of the Tauranga Group have yielded a remarkable diversity of fossils, including fruits, seeds, vascular and non-vascular leaves, wood, amber, pollen, spores, fungi, mites and other arthropod fragments. The specimens are mostly organically-preserved and retain fine details such as leaf cuticle, fungal-spore ornamentation and endocarp/cone cellular patterns that complement their macro-morphology.
Globally uncommon fossil types preserved in these sediments include bracket fungus basidiocarps (polypores) and moss gametophytes (Bryophyta). Many fossil moss specimens are exquisitely preserved and taxa such as Calyptrochaeta cristata, Pyrrhobryum, Fissidens, Ptychomnion, Hypnodendraceae, Neckeraceae and Sematophyllaceae are recognisable.
A high diversity of fossil fruits, seeds and cones is present: these indicate a strong discordance between the modern flora of northern New Zealand and that of the Late Pliocene. A few of the fossil fruits and seeds such as Prumnopitys, Passiflora and Elaeocarpus share affinities with extant taxa, but the majority belong to locally extinct groups such as Vitaceae, Menispermaceae, Casuarinaceae, Brassospora-type Nothofagus, an uncertain genus of Cupressaceae and several large-fruited species of Elaeocarpus. Abundant unidentified diaspores at the sites almost certainly represent groups now extinct in New Zealand. The fossil leaf flora includes Lauraceae, Myrtaceae, Elaeocarpaceae, Nothofagus and ?Rubus and diverse conifers. The latter superficially resemble extant Prumnopitys, Libocedrus, Podocarpus, Dacrycarpus, Dacrydium and Phyllocladus. The fossil leaf flora extends the list of fossil plants; however, its degree of similarity to the modern flora is as yet unclear.
These fossil plants represent an unparalleled glimpse into the ecosystems and species living in northern New Zealand near the end of the Pliocene. High rates of observed floristic turnover in some fossil groups were probably associated with the general cooling and/or climatic fluctuations of the Pleistocene that followed relatively soon after these fossils were deposited.


1 - University of Otago, Department of Geology, PO Box 56, Dunedin, New Zealand
2 - Manaaki Whenua Landcare Research, 231 Morrin Rd, St Johns, Auckland, New Zealand
3 - Geomarine Research, 19 Debron Ave, Remuera, Auckland, New Zealand
4 - The University Of Adelaide, School Of Biological Sciences, Benham Bldg, DX650 312, Adelaide, SA 5005, Australia
5 - University of Otago, Department of Botany, PO Box 56, Dunedin, New Zealand

Keywords:
paleobotany
Fossil bryophytes
fossil fungi
Fossil seeds.

Presentation Type: Oral Paper
Number:
Abstract ID:731
Candidate for Awards:Isabel Cookson Award


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