Permineralized conifer-like leaves from the Jurassic of Patagonia (Argentina) and its paleoenvironmental implications

Abstract

Anatomically preserved conifer-like leaves from the Middle Jurassic La Matilde Formation at the Barda Blanca locality in the Gran Bajo de San Julián area, southern Patagonia are described here. Leaves are assigned to conifers based on the following foliar features: thick-walled epidermal cells, a sclerenchymatic hypodermis, resin canals and transfusion tracheids associated with the vascular bundle. General mesophyll anatomy and inferred foliar morphology suggest a similarity to large, broad, linearlanceolate, multi-veined conifer-like leaves. The general foliar habit indicates an affinity with the large, multi-veined leaves of the Araucariaceae; especially with those exhibited by the species of the Araucaria sections, Araucaria and Bunya. Anatomically, the permineralized leaves exhibit xeromorphic foliar features, including thick-walled epidermal cells, an isobilateral mesophyll with well-developed palisade cells and mechanical tissue. the general leaf anatomy shown by the Patagonian specimens along with sedimentological data may suggest that during the deposition of the La Matilde Formation at the Barda Blanca locality, the parent plant was well adapted to the environmental conditions, which probably consisted of a high light intensity with an adequate quantity of water in the soil, which increased the maximum leaf conductance of CO 2 .

Diversification of crown groupAraucaria: the role ofAraucaria famiisp. nov. in the Late Cretaceous (Campanian) radiation of Araucariaceae in the Northern Hemisphere

“…They are rhomboidal and imbricate and somewhat fleshy with conspicuous abaxial fiber bands, but that lack palisade parenchyma. By contrast, the broad-leaved araucarians that have been described do have a palisade (Mastroberti and Mariath, 2003;Del Fueyo et al, 2019). "Compartmented cells" (Bamber et al, 1978) have been described in 10 of the species of Araucaria in the spongy parenchyma mostly near the abaxial side of the leaf (Bamber et al, 1978;Mastroberti and Mariath, 2003) as well as in Wollemia nobilis (Burrows and Bullock, 1999).…”

“…20I). Other species such as A. angustifolia (Mastroberti and Mariath, 2003), have a narrow, one-or two-celled thick hypodermis, while in A. araucana the hypodermis is thicker (Del Fueyo et al, 2019). This character needs to be studied in more detail in a larger number of extant Araucaria species.…”

Maceral Association in Coal-bearing Formation of Mae Than Coal Mine in Lampang, Thailand - Implication for Depositional Environment

“…In this study, cutinite exhibits clear cuticular ledges and shows well-preserved morphology. A needle-like cutinite (Figure 6 (a)) indicates a leaf of a conifer (Del Fueyo et al, 2019). These indicate a slightly reducing to strongly reducing condition of the deposit (Pophare et al, 2014;Stach et al, 1982).…”