Abstract Detail

Paleobotanical Section

Parrott, Joan [1], Upchurch, Garland [2], Mack, Greg [3].

McRae Formation Icacinoxylon and Platanoids: Components of a Late Cretaceous Wood Flora From South-Central New Mexico.

The Jose Creek Member of the McRae Formation in south-central New Mexico preserves an abundant and diverse flora of angiosperm wood and leaves of Late Cretaceous (Campanian) age. Recent reports of fossil woods from the Jose Creek Member include taxa not yet known from its leaf record, including Celastraceae and Myrtaceae. Evidence from nine newly collected specimens indicates multiple types of angiosperm wood, in addition to two previously known from the Jose Creek Member, representing Plataninium/Platanoxylon/Icacinoxylon wood types common in the Late Cretaceous. All woods have primarily solitary vessels with scalariform perforation plates, larger rays >10 cells in width and > l mm in height, and fibers with distinctly bordered pits visible on both radial and tangential walls. One specimen with heterocellular rays of two sizes is assignable to Icacinoxylon. The remaining specimens have homocellular to not markedly heterocellular rays and are tentatively identified as platanoid-type. Three of the platanoid-type specimens have abundant diffuse-in-aggregates axial parenchyma with short uniseriate lines. These are divisible into two morphotypes based on the frequency of scalariform intervessel pitting, number of bars per scalariform perforation plate, mean vessel diameter and vessel element height, and presence or absence of septate fibers, the last of which is absent from extant Platanaceae. Two other platanoid-type specimens add detail to the description of a previously illustrated morphotype with the largest mean vessel diameters and vessels in tangential multiples. The remaining three platanoid-type specimens supplement the description of a previously illustrated morphotype with axial parenchyma scanty paratracheal or diffuse-in-aggregates, and predominantly wide, tall rays. One wood specimen represents the basal part of a tree trunk 40 cm in diameter, while the others represent isolated axes with minimum diameters of 5 – 30 cm indicating a minimum stature of shrub to small tree. Leaf megafossils from the Jose Creek Member and elsewhere are consistent with the diversity of woods with Platanaceous features.

1 - 207 Pioneer Trail, San Marcos, TX, USA
2 - Texas State University, Department Of Biology, 601 University Drive, San Marcos, TX, 78666, USA
3 - New Mexico State University, Department of Geological Sciences, P.O.Box 30001, Las Cruces, NM, 88003, USA

Keywords:
fossil wood
Late Cretaceous.

Presentation Type: Oral Paper:Papers for Sections
Session: 11
Location: Salon 5/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 11:30 AM
Number: 11006
Abstract ID:905
Candidate for Awards:Isabel Cookson Award