The distinct foliar physiognomy of the Late Cretaceous forests of New Zealand — Probably deciduous

Abstract

Three features of leaf physiognomy: craspedodromous venation, compound teeth and a lobed leaf outline, figure prominently in the Late Cretaceous vegetation of southern New Zealand. These make it distinctly different from typical extant, predominantly evergreen forests and some deciduous vegetation. The physiognomy of the Late Cretaceous vegetation at the assemblage level shows more similarity with predominantly deciduous forests of the Northern Hemisphere, in terms of the proportions of these characters in the flora. At the taxon level, combinations of characters found in fossils are very similar to and in some cases restricted to, widespread extant Northern Hemisphere deciduous taxa, but also to rarer components of evergreen forests. It may not be possible to categorically determine whether any one fossil was deciduous. The distinctly different assemblage-level foliar physiognomy implies a distinctly different “lifestyle” for the New Zealand forests that bordered Gondwana in the Late Cretaceous. It is highly likely that this physiognomy reflects an important deciduous component. This is unexpected as for at least part of this time New Zealand was apparently below (north of) the Polar Circle with a temperate and everwet climate.