Vazquez Rueda, Mar Allesha , Calvillo-Canadell, Laura , Cevallos-Ferriz, Sergio .
Infructescence from the Cerro del Pueblo Formation, Upper Cretaceous, Coahuila, Mexico.
A permineralized infructescence is described based on the observation of 584 samples and ca. 250 thin sections for anatomical interpretation The material was collected in the San Antonio Dam, Town of Parras, in sediments of the Cerro del Pueblo Formation, Coahuila, Mexico, of Upper Cretaceous (late Campanian-Maastrichtian) age. It is woody, long and consists of ca. 120-150 individual fruits of the nut type, arranged spirally on a robust stem. Each fruit is covered by bracts, which consist of an epidermis of rectangular cell, and 2-5 layers of hexagonal cells towards the distal zone and 2-3 cell layers of circular cells near the proximal, these cells have rick walls. Each fruit has a short pedicel and mostly 2 carpels, but these may vary (2-4). The fruits aredry, indehiscent, and develop from syncarpous (bi to tetracarpelated) superiorovaries, with apical style and stigma. The fruits may have abortive seeds, butgenerally have a fusiform seeds with axial placentation developed from an epitropous ovule. The ovary has 2 cell layers; the exocarp is woody and is composed of asingle row of macrosclereid. The mesocarp and endocarp are composed of rectangular cells with dark persistent contents, and a cuticle surrounds the ovary limiting it from a space separating the fruit of the seeds. The funicle and hilum are poorly differentiated, rectangular cells represent an epidermis and thin-walled circular cells fill the structures. The seed coat is composed of a row of rectangular cells. Nuclear endosperm is located in the periphery ofthe seed, while helobial endosperm is located towards the see center and grouped close to the placenta. A constant structure in the seed is a chamber in the distal region, which is surrounded by nuclear endosperm followed outwardlyby the helobial endosperm. In the embryo an epicotyl area with two cotyledons surrounding the apical meristem and a hypocotyl area are recognized. All these features are found in members of Proteales. For example, camera and endosperm development are similar to those reported in Nelumbonaceae, Platanaceae and Proteaceae, although the external morphological appearance is similar to a Banksia infructescence (Protaceae), suggesting that the new material represents an extinct Proteales member, and adding a new record of Cretaceous plants that lived in the Northern Hemisphere, but are most common today in the Southern Hemisphere.
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1 - Faculty Of Science, UNAM, Paleontology, Sierra Picacho No. 80 Parque Residencial Coacalco. Edo De Méx., Estado De México, N/A, 55720, Mexico
2 - Instituto De Geología, UNAM, Circuito De La Investigación, Ciudad Universitaria, Coyoacan, N/A, 04510, Mexico
3 - Instituto De Geología, UNAM, Department Of Palentology, Ciudad Univwersitaria, Coyoacan, MEXICO D.F., N/A, 01900, Mexico
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Monday, July 9th, 2012
Time: 2:00 PM