Journal of the Geological Society Leaf habit of Late Permian Glossopteris trees from high-palaeolatitude forests by Erik L. Gulbranson, Patricia E. Ryberg, Anne-Laure Decombeix, Edith L. Taylor, Thomas N. Taylor, and John L. Isbell Journal of the Geological Society Volume 171(4):493-507 July 1, 2014 © 2014 The Geological Society of London

Comparison of modern climate and biomes with those reconstructed for the latest Permian climate and biomes. Comparison of modern climate and biomes with those reconstructed for the latest Permian climate and biomes. (a) Present-day distribution of climate regimes. Some Köppen–Geiger climate zones are not shown or are grouped together to make a more direct comparison with latest Permian climates (modified from Kottek et al. 2006). Boreal forests (Dfa–Dfb to Dfc) are predominantly evergreen, whereas temperate forests are dominated by deciduous trees (Cfa to Dfa–Dfb). (b) Latest Permian climate reconstruction (modified from Rees et al. 2002; Kiehl & Shields 2006; Horton & Poulsen 2009; Roscher et al. 2011). The Glossopteris flora occurs in the Southern Hemisphere Dfa–Dfb to Dfc zones and is interpreted to be deciduous. The southernmost part of Gondwana was interpreted to be a tundra ecosystem by Rees et al. (2002), but modelled temperature using a dynamic ocean–atmosphere model produces conditions more favourable for forest growth (Kiehl & Shields 2005; Roscher et al. 2011). Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Study area in Antarctica and reconstructions of the three fossil forests. Study area in Antarctica and reconstructions of the three fossil forests. (a) Map of the study area in the central Transantarctic Mountains showing the three studied fossil forests at Graphite Peak, Wahl Glacier, and Mt. Achernar. (b–d) Fossil forest reconstructions (after Gulbranson et al. 2012) showing tree positions and average tree heights for Mt. Achernar and Wahl Glacier, and tree height estimates for each tree at the Graphite Peak fossil forest. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Conceptual model of δ13C patterns in tree rings (modified from Gulbranson & Ryberg 2013). Conceptual model of δ13C patterns in tree rings (modified from Gulbranson & Ryberg 2013). (a) δ13C patterns of a ring in an evergreen tree. (b) δ13C patterns of a ring in a deciduous tree; numbers correspond to a three-phase model to explain the physiological basis for this variation in δ13C values. Vertical dotted lines indicate ring boundaries; continuous black lines indicate δ13C values of wood. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Photomicrographs of fossil wood specimens illustrating the anatomy and affinities with Australoxylon. Photomicrographs of fossil wood specimens illustrating the anatomy and affinities with Australoxylon. (a) General aspect of the wood in transverse section; slide WG-6 tr (specimen 17,775). (b, c) Detail of growth ring anatomy in two specimens showing the latewood of one growth season (bottom), distinct ring boundary, and earlywood of the next growth season (top); slides WG-6 tr (b) and MA-1 tr (c; specimen 17,169). (d, e) Radial sections showing cross-field pitting with numerous small crowded pits; slides WG-6 ra (d) and WG-10 ra (e; specimen 17,776). (f, g) Tangential sections showing uniseriate rays, with a partly biseriate ray formed by the fusion of two uniseriate rays (black arrow in (f)); slides WG-6 ta (f) and MA-1 ta (g). (h, i) Mixed pitting on the radial wall of tracheids; slide WG-5 ra (specimen 17,774): uniseriate pits with both spaced (s) and contiguous (c) arrangement shown in (h); uniseriate spaced (s) and multiseriate crowded (c) pits in (i). (j) Grouped pits typical of Australoxylon (arrows); slide WG-5 ra. Scale bars represent 1 mm for (a); 100 µm for (b), (c) and (f); 50 µm for (g); 25 µm for (d), (e) and (h)–(j). Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Tree ring measurements for Late Permian wood. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Ring width data for the studied wood specimens. Ring width data for the studied wood specimens. Annual sensitivities (AS) >0.3 are interpreted to reflect stressed conditions, and AS values < 0.3 are interpreted as growth intervals with less environmental stress. Shaded areas in (b), (d) and (f) correspond to the intervals used for carbon isotope analysis. (a, c, e) Histogram of annual sensitivity results for each specimen from the study localities: (a) Mt. Achernar; (c) Wahl Glacier; (e) Graphite Peak. (b, d, f) Annual sensitivity results plotted along the growth direction for each specimen from the study localities: (b) Mt. Achernar; (d) Wahl Glacier; (f) Graphite Peak. Direction of growth is from left to right. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Tracheid cell diameters versus cell number across single rings from three representative specimens. Tracheid cell diameters versus cell number across single rings from three representative specimens. Vertical lines indicate the apex (dashed line) of the CSDM curve and centre (continuous line) of the CSDM curve. The difference and location of the apex versus the centre of the CSDM curve can be used as a proxy for leaf habit (Falcon-Lang 2000). (a) CSDM for specimen 17,771, (b) CSDM for specimen 17,169; (c) CSDM for specimen 17,774. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Criteria for inferring leaf habit from tree ring δ13C values. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Stable carbon isotope results for Mt Stable carbon isotope results for Mt. Achernar wood specimens: (a) specimen 17,169; (b) specimen 11,617B; (c) specimen 11,472A (MA-3). Stable carbon isotope results for Mt. Achernar wood specimens: (a) specimen 17,169; (b) specimen 11,617B; (c) specimen 11,472A (MA-3). Data points reflect single microsamples collected along the direction of growth; ring boundaries are indicated by vertical dotted lines. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Stable carbon isotope results for Wahl Glacier wood specimens: (a) specimen 17,774; (b) specimen 17,775; (c) specimen 17,776. Stable carbon isotope results for Wahl Glacier wood specimens: (a) specimen 17,774; (b) specimen 17,775; (c) specimen 17,776. Data points reflect single microsamples collected along the direction of growth; ring boundaries are indicated by vertical dotted lines. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Stable carbon isotope results for Graphite Peak wood specimens: (a) specimen 17,771; (b) specimen 17,772. Stable carbon isotope results for Graphite Peak wood specimens: (a) specimen 17,771; (b) specimen 17,772. Data points reflect single microsamples collected along the direction of growth; ring boundaries are indicated by vertical dotted lines. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London

Mean δ13C values for wood samples versus reconstruction of the fossil forests. Mean δ13C values for wood samples versus reconstruction of the fossil forests. (a) Means and standard deviations for δ13C values for wood specimens from Graphite Peak, Wahl Glacier, and Mt. Achernar versus the log10 of tree density estimated for each fossil forest; n, number of data points used. Despite the overlap, Mt. Achernar and Wahl Glacier mean δ13C values are significantly different based on an F-statistic of 29.836 (P < 0.0001) with a DF of 218. (b) Basal area of wood (solid line) and tree height (dotted line) versus log10 tree density for each fossil forest. Erik L. Gulbranson et al. Journal of the Geological Society 2014;171:493-507 © 2014 The Geological Society of London