PROTEOKALON A NEW GENUS OF PROGYMNOSPERMS FROM THE DEVONIAN OF NEW YORK STATE AND ITS BEARING ON PHYLOGENETIC TRENDS IN THE GROUP

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Abstract
Proteokalon gen. nov. is described from the Upper Devonian Catskill deposits of New York. Two orders of branching and ultimate appendages are preserved' by petrifaction and by compression. The first order bears branches decussately and has a skewed four‐armed protostele that occasionally dichotomizes. Second‐order branches dichotomize rarely and most have T‐shaped or three‐armed protosteles. They bear ultimate appendages alternately, either in lateral pairs, or singly from the abaxial side. These appendages divide several times in one plane. Their vascular strand is terete. Maturation of the primary xylem is mesarch, and it consists of tracheids and parenchyma. Secondary xylem and phloem and a periderm are present. The outer cortex has a system of hypodermal fibers. Proteokalon is most similar to Tetraxylopteris and Triloboxylon of the Aneurophytales. A comparison of the stratigraphic occurrence of Protopteridium, Aneurophyton, Tetraxylopterism, Sphenoxylon, Triloboxylon, and Proteokalon suggests some evolutionary trends among the Aneurophytales.
Funding Information
  • National Science Foundation (GB‐4493, GB‐8282)