Table 2.
Summary of palaeoenvironmental indicators
| Wood functional–anatomical traits | No. of taxa | % occurrence | Significance |
|---|---|---|---|
| Few, wide vessels | 3/30 | 10 | Not occurring outside the tropics (indicates frost-free climates). Limited to wet tropical forest and deep-rooted trees in environments where water is not limiting for growth. |
| Semi-ring porosity | 6/30 | 25 | More prevalent than in modern South American dry-to-wet tropical forests. Establishes deciduous component to the flora (Boura & Francheschi, 2007). Includes complex patterns indicating a different pattern of water need compared to the present? |
| Vessels in radial multiples or clusters | 8/29 | 28 | Values high for the modern tropical flora, intermediate between very dry and more mesic tropical forest. |
| Helical vessel thickenings | 3/30 | 10 | Rare/absent in the present-day tropics. Linked to water stress and climate seasonality (Wheeler & Baas 2019). |
| Wood quantitative variables | Av. | ||
| Estimated specific gravity | 0.49 ± 0.11 | Values low for tropical forest but within the range of tropical forest types. Indicates low-biomass association. Values < 0.4 are a tropical indicator. | |
| Vessel diameter & density | Large ranges typical of tropical forest; large range in vessel diameter reflecting the range of tree heights expected for tropical forest. | ||
| Vessel diameter & density means comparisons | Fossil assemblage significantly different from driest forest. | ||
| Vessel element length | 339 ± 123 µm | Values low relative to modern tropical flora and lengths ≥ 800 µm not present, consistent with the fossil/modern disjunction described by Wheeler and Baas (2019). Long vessel elements linked to mesic conditions (Carlquist, 1988). | |
| Intervessel pit diameter | 6.5 ± 1.8 µm | Values low relative to modern tropical flora. | |
| Degree of vessel grouping means comparisons | Means comparisons not significant but some taxa show a high degree of vessel grouping relative to modern tropical associations. | ||
| Leaves | |||
| Leaves 100 % entire-margined (n = 23) | Tropical temperature indicator. | ||
| Leaves notophylls to microphylls (megaphylls absent) | Indicates relatively dry conditions; distinct from wet lowland tropical forest with megaphylls predominating. | ||
| Leaf margin & area analysis | |||
| Eq. in Wilf, 1997 | MAT 31°C | ||
| Eq. in Wilf et al., 1998 | MAP 1290 mm |