A new species of Eoginkgoites from the Upper Triassic of North Carolina, USA

Abstract

The foliage genus Eoginkgoites represents a superficially ginkgoalean bennettitalean leaf restricted to the Late Triassic of North America. A new species, Eoginkgoites sydneyi is described from the Pekin Formation in North Carolina. The number of lateral pinna pairs is typically four, but varies from three to five. Previously described species have a maximum of three lateral pairs. The new form is most similar in morphology to E. gigantea from the upper Stockton Formation of Pennsylvania. Eoginkgoites sydneyi and the Chinle Formation species E. davidsonii share several cuticular features unusual to the Bennettitales including straight anticlinal epidermal cell walls and radiating striations on the stomata guard cell thickenings. The additional pinna pairs of the new species suggests support for the hypothesis that the Eoginkgoites leaf morphology was derived from a typical pinnate form by loss of lower pinnae and shortening of the rachis. Recognition of this unusual leaf morphology in the Triassic provides further evidence for an emerging picture of greater morphological diversity in the early Bennettitales.