New Late Cretaceous and Paleocene Dicot Woods of Big Bend National Park, Texas and Review of Cretacous Wood Characteristics

Abstract

Three new wood types from the Late Cretaceous and one from the Paleocene of Big Bend National Park, Texas, U.S.A. add to our knowledge of North American Late Cretaceous and Paleocene plants. Sabinoxylon wicki sp. nov. provides further evidence of similarities in late Campanian-early Maastrichtian vegetation of Texas, New Mexico, and northern Mexico. This species is characterized by mostly solitary vessels, scalariform perforation plates, vessel-ray parenchyma pits similar to intervessel pits, vasicentric tracheids, and two size classes of rays. Storage tissue accounts for close to 50% of its wood volume. Another of the new Cretaceous wood types, referred to as Big Bend Ericalean Wood Type I, has more than 40% ray parenchyma. Both Big Bend Ericalean Wood Type I and Sabinoxylon have a combination of characters that occurs in the order Ericales (sensu APGII). The third new Cretaceous wood type is from a small axis (less than 3 cm diameter), and has a combination of features that is the most common pattern in extant eudicots (vessels solitary and in radial multiples randomly arranged, simple perforation plates and alternate intervessel pits, and heterocellular rays). The Paleocene wood (cf. Cunonioxylon sensu Gottwald) differs from all other North American Paleocene woods and has characteristics found in the predominantly Southern Hemisphere family Cunoniaceae. The characteristics of these new Big Bend woods contribute to a database for fossil angiosperm woods, and allow for comparison of incidences of selected wood anatomical features in Northern Hemisphere Cretaceous woods from Albian to Maastrichtian time as well as comparison with extant woods. Cretaceous woods as a whole differ from Recent woods in having higher incidences of exclusively solitary vessels, scalariform perforation plates, and wide rays (>10-seriate), and lower incidences of ring porosity, wide vessels (>200 μm), vessels in groups, non-random arrangements of vessels, and marginal parenchyma. The occurrence of relatively high percentages of storage cells (>40%) in some Cretaceous trees is noteworthy; the ability to produce wood with varying amounts and arrangements of parenchyma is likely to be a contributing factor to the success of angiosperm trees in a wide variety of environments.

Fossil evidence for Cretaceous escalation in angiosperm leaf vein evolution

“…Fossilized logs up to 1 m in diameter with the xylem plumbed by large-diameter (≥200 μm) vessels and simple perforation plates are first found in the mid-Cretaceous (23,(25)(26)(27)(28). That a large shift in angiosperm body size, wood hydraulic efficiency, and, as we now show, moderately high D V emerged synchronously points to a coordinated whole plant transformation in angiosperm hydraulic capacity during the mid-Cretaceous (19)(20)(21).…”

“…The second Maastrichtian-Paleocene surge in angiosperm D V corresponds with the key time interval for when (i) angiosperms radiated into and dominated diverse environments, including late successional zones of mesothermal forests and megathermal peat-and coal-forming environments; and (ii) when angiosperm ecological abundance first eclipsed ferns and conifers across several biomes (13,14,23,24,28,29). These fossil patterns are consistent with a major expansion in angiosperm competitive ability, which is supported by our finding that D V values associated with the most productive extant angiosperm forests first emerge during the Late Cretaceous (1).…”

Maderas fósiles de la Formación San Carlos (Cretácico Superior), Chihuahua, México

“…San Carlos corresponde a una angiosperma; cuyas características anatómicas son similares a las encontradas en Paraphyllanthoxylon, planta común durante el Cretácico y a lo largo del Cenozoico (Bailey, 1924;Martínez-Cabrera et al, 2006;Gregory et al, 2009;Wheeler y Lehman, 2009;Estrada-Ruiz et al, 2012a). Las principales características cuantitativas y cualitativas de las especies cretácicas que conforman al género fósil Paraphyllanthoxylon se resumen en la Tabla 1.…”

“…Paraphyllanthoxylon fue descrita por Bailey (1924) del Cretácico Superior de Arizona, EUA; esta madera se caracteriza por la ausencia de anillos de crecimiento, porosidad difusa, vasos solitarios y en múltiplos radiales cortos, exclusivamente placas de perforación simples, punteaduras intervasculares alternas, punteaduras vaso-radio y vaso-parénquima con bordes reducidos, abundante tílidis, parénquima axial raro o escaso, fibras septadas sin punteaduras visibles y radios multiseriados heterocelulares (Bailey, 1924;Wheeler y Lehman, 2009). La afinidad del género Paraphyllanthoxylon es incierta y hasta la fecha su inclusión en alguna familia en particular se sigue discutiendo.…”

“…Se han descrito varias especies cretácicas de Paraphyllanthoxylon en distintas localidades de América del Norte, Asia y Europa (Gregory et al, 2009;Wheeler y Lehman 2009). Bailey (1924) describe por vez primera el género Paraphyllanthoxylon.…”