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Fossil evidence for low gas exchange capacities for Early Cretaceous angiosperm leaves

journal contribution
posted on 2023-05-17, 07:10 authored by Feild, TS, Upchurch, GR, Chatelet, DS, Timothy BrodribbTimothy Brodribb, Grubbs, KC, Samain, M, Wanke, S
The photosynthetic gas exchange capacities of early angiosperms remain enigmatic. Nevertheless, many hypotheses about the causes of early angiosperm success and how angiosperms influenced Mesozoic ecosystem function hinge on understanding the maximum capacity for early angiosperm metabolism. We applied structure-functional analyses of leaf veins and stomatal pore geometry to determine the hydraulic and diffusive gas exchange capacities of Early Cretaceous fossil leaves. All of the late Aptian–early Albian angiosperms measured possessed low vein density and low maximal stomatal pore area, indicating low leaf gas exchange capacities in comparison to modern ecologically dominant angiosperms. Gas exchange capacities for Early Cretaceous angiosperms were equivalent or lower than ferns and gymnosperms. Fossil leaf taxa from Aptian to Paleocene sediments previously identified as putative stem-lineages to Austrobaileyales and Chloranthales had the same gas exchange capacities and possibly leaf water relations of their living relatives. Our results provide fossil evidence for the hypothesis that high leaf gas exchange capacity is a derived feature of later angiosperm evolution. In addition, the leaf gas exchange functions of austrobaileyoid and chloranthoid fossils support the hypothesis that comparative research on the biology of living basal angiosperm lineages reveals genuine signals of Early Cretaceous angiosperm ecophysiology.

History

Publication title

Paleobiology

Volume

37

Pagination

195-213

ISSN

0094-8373

Department/School

School of Natural Sciences

Publisher

Paleontological Soc Inc

Place of publication

810 East 10Th St, Lawrence, USA, Ks, 66044

Rights statement

Copyright © The Paleontological Society 2011

Repository Status

  • Restricted

Socio-economic Objectives

Terrestrial biodiversity

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