AN ARAUCARIAN CONIFER BRACT-SCALE COMPLEX FROM THE LOWER
JURASSIC OF MASSACHUSETTS: IMPLICATIONS FOR ESTIMATING PHYLOGENETIC AND STRATIGRAPHIC
CONGRUENCE IN THE ARAUCARIACEAE
The conifer family Araucariaceae has an extensive Mesozoic fossil record, but no unambiguous megafossils of this group have been described from the Newark Supergroup of eastern North America. A bract-scale complex attributable to Araucaria is described from the Lower Jurassic Portland Formation of Massachusetts. Although known from a single specimen, this discovery is significant as the first bona fide megafossil of the Araucariaceae from the Newark Supergroup and one of the few early Mesozoic examples from all of North America. Furthermore, this bract-scale complex is proposed as the earliest known occurrence of Araucaria section Eutacta based on its wedge-like shape, the centrally placed ovule that was retained at maturity, and lateral wings. An analysis of the relationship between the most current phylogenetic hypotheses for the sections of Araucaria and the temporal information from the rich fossil record of the genus indicates low levels of congruence. Clearly, more paleobotantical and phylogenetic research is needed to provide a robust estimate of this important conifer family's evolutionary history.
Brian J. Axsmith. Department of Biology, University of South Alabama, LSCB 124, Mobile, Alabama 36688, U.S.A.
Ignacio H. Escapa. CONICET, Museo Paleontologico Egidio Feruglio, Fontana 140, Trelew,
Phillip Huber. GeoScience Books, P.O. Box 1036, Faribault,
Minnesota 55021, U.S.A.
KEY WORDS: Eutacta; phylogenetics; Mesozoic; Newark Supergroup; Portland Formation
PE Article Number: 11.3.13A
Copyright: Palaeontological Association October 2008
Submission: 29 December 2007. Acceptance: 19 April 2008.