DOI: 10.5061/dryad.j0k8370
title: Data from: Early Paleocene tropical forest from the Ojo Alamo Sandstone, San Juan Basin, New Mexico, USA

description: Earliest Paleocene megafloras from North America are hypothesized to be
 low diversity and dominated by long-lived cosmopolitan species following
 the Cretaceous-Paleogene (K/Pg) mass extinction. However, megafloras used
 to develop this hypothesis are from the Northern Great Plains of North
 America, and relatively little is known about floras from southern basins.
 Here, we present a quantitative analysis of an earliest Paleocene
 megaflora (&lt;350 kyr after K/Pg boundary) from the Ojo Alamo
 Sandstone in the San Juan Basin (SJB), New Mexico. The megaflora,
 comprised of 53 morphotypes, was dominated by angiosperms, with accessory
 taxa composed of pteridophytes, lycophytes, and conifers. Diversity
 analyses indicate a species rich, highly uneven, and laterally
 heterogeneous flora. Paleoclimate estimates using multivariate and
 univariate methods indicate warm temperatures and relatively high
 precipitation consistent with a modern tropical seasonal forest. When
 compared to contemporaneous floras from the Denver Basin (DB) of Colorado
 and the Williston Basin (WB) of North Dakota, the SJB flora had
 significantly higher species richness but lower evenness. Paleoclimate
 estimates from the SJB were 7-14 °C warmer than the DB and WB, indicating
 a shift from a temperate forest in the Northern Great Plains to a tropical
 forest in the SJB. These results demonstrate the presence of a latitudinal
 floral diversity and paleoclimatic gradient during the earliest Paleocene
 in western North America. We hypothesize that the warm, wet conditions in
 the earliest Paleocene SJB drove rapid rates of speciation following the
 K/Pg boundary resulting in a diverse and heterogenous flora.
description: Supplementary Tables
 1-8Supplementary Tables 1-8
 which includes (1) systematic list of megafloral morphotypes from the San
 Juan Basin, (2) stratigraphic position, depositional facies, location, and
 morphotype tallies for all floral sites, (3) megafloral census data, (4)
 megafloral presence-absence data, (5) total Ojo Alamo Sandstone and facies
 mean physiognomic variables using the DiLP paleoclimate calculation, (6)
 measured leaf physiognomy values for all measureable
 specimens/morphotypes, (7) regional diversity comparison, and (8) -
 calculated p-values for Margalef Index, Pielou's Evenness, and
 Berger-Parker Index for all San Juan Basin, Denver Basin, and Williston
 Basin diversity indice comparison.Appendix 1 - Morphotype
 CatalogOjo Alamo Sandstone
 Morphotype Catalog Morphological descriptions, botanical affinities,
 photographs, and line drawings of all identified Ojo Alamo Sandstone
 megafloral morphotypes. All dicotyledonous angiosperm leaf morphotypes
 were described using the Manual of Leaf Architecture (Ellis et al. 2009).
 Each dicotyledonous angiosperm leaf morphotype description contains leaf
 architecture description, margin classification, and Raunkiaer-Webb (Webb
 1959) size classification. All other groups (i.e. dicotyledonous
 angiosperm reproductive structures, pteridophytes, monocotyledonous
 angiosperms, and conifers) were described based on their gross morphology.
 Botanical affinities of morphotypes were determined after comparison with
 previously published taxonomy. Each morphotype also has a specimen number
 which corresponds with the morphotype exemplar. See Supplementary Table 1
 for detailed systematic morphotype list and Supplementary Table 2 for
 morphotype abundance by fossil locality.Morphotype
 Catalog.pdfSupplementary Figure 1 -
 Facies and Formation Photos SmallGeneralized latest
 Cretaceous and earliest Paleocene stratigraphic units and Ojo Alamo
 Sandstone lithofacies. A: contact between the Maastrichtian Naashoibito
 Member of the Kirtland/Fruitland Formation and the overlying earliest
 Paleocene Ojo Alamo Sandstone. B: the contact between the earliest
 Paleocene Ojo Alamo Sandstone and overlying early Paleocene Nacimiento
 Formation. C: representative overbank leaf Locality AF1409D in the Ojo
 Alamo Sandstone. D: closeup of the overbank flora deposits which are
 interbedded siltstone and medium to coarse grained sandstone and have been
 interpreted to represent downstream accretionary bars. E: is a coarse
 grained cross-bedded sandstone with occasional gravel lag deposits which
 account for the majority of the Ojo Alamo Sandstone. F: representative
 pond/swamp floral locality AF1407 and the contact between earliest
 Paleocene Ojo Alamo Sandstone and early Paleocene Nacimiento Formation. G:
 close up of pond/swamp leaf locality AF1407 showing fine grained
 carbonaceous shales typical of pond/swamp floral
 facies.Supplementary Figure 2 -
 Digital Leaf Physiognomy ExamplesExamples of the 4
 different types of leaves prepared for digital leaf physiognomy (DiLP)
 following the protocol of Peppe et al. 2011. All digital preparation was
 done using Adobe Photoshop.Supplementary Figure 2 with
 Caption.pdf