Abstract Detail



Paleobotany

Parrott, Joan [1].

Assignment of the Paraphyllanthoxylon-like wood from the Forest of Giants, McRae Formation of Late Cretaceous South-Central New Mexico, to a new fossil genus within Kirkiaceae.

The Forest of Giants is an assemblage of 15 exceptionally large in situ stumps and 5 logs from the Jose Creek Member of the late Campanian (76.5 to 72.5 myr) McRae Formation, south-central New Mexico, that represent riparian forest preserved in a sequence of fluvial sandstones. Four angiosperm xylotypes have been recognized including woods tentatively assigned to Lauraceae, Sapotaceae and a Rosales with similarities to the clade Cannabaceae, Urticaceae and Moraceae. The most common Forest of Giants xylotype has features generally congruous with Paraphyllanthoxylon, excepting unusual cells present in the rays that are not known from the type species of the genus. Search of the InsideWood database and the literature suggest affinity with the monophyletic clade Kirkiaceae, Anacardiaceae and Burseraceae. Greatest similarity is found in the comparison between the fossil wood and species in Kirkia (Kirkiaceae). Shared features include vessels that are solitary and in radial multiples of 2–3, simple perforation plates, alternate intervessel pits, vessel-ray parenchyma pitting with reduced borders, scanty paratracheal axial parenchyma, rays 2–4 (up to 5 or 6) seriate, and septate fibers. Cells in the rays of Kirkia acuminata, interpreted as gum cells, appear to match the unusual ray cells observed in the fossil wood. Assignment of the McRae wood to a new fossil genus within Kirkiaceae represents a departure from previous analyses that maintain Paraphyllanthoxylon-like woods have anatomical features consistent with many families and should be assigned to a form genus. The finding for this particular wood does not exclude other Paraphyllanthoxylon-like woods from affinity with Laurales, another widely accepted interpretation for Paraphyllanthoxylon species. William Spackman first suggested similarity of Paraphyllanthoxylon­-like woods with Anacardiaceae, Burseraceae and Kirkiaceae in 1948. At that time, Spackman excluded Kirkiaceae as the likely affinity because of the “ray type” observed in Kirkia acuminata.


1 - Texas State University, Department of Biology, 601 University Drive, San Marcos, TX, 78666, USA

Keywords:
none specified

Presentation Type: Oral Paper
Number: 0004
Abstract ID:290
Candidate for Awards:None


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