| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Paleobotany |
Museum of Paleontology, University of Michigan, Ann Arbor, Michigan 48109-1079 USA
Received for publication December 16, 2003. Accepted for publication August 3, 2004.
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Key Words: anemochory • dry tropical forest • Ecuador • Loxopterygium • paleobotany • Tertiary • winged diaspores
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
; Manchester and Hably, 1997
; Wang and Manchester, 2000
; McClain and Manchester, 2003
). Angiosperm fruits are ideal sources of phylogenetic information from the fossil record because angiosperm morphological taxonomy is frequently based on the reproductive features of plants and their fruits often reveal critical reproductive details (e.g., ovary position, style, locule number, etc.). Documentation of the occurrence of a genus or family at a particular time-period can be established because the critical features of specific clades are well known for reproductive organs of plants.
Asymmetrically winged fruits, or samaras, have been reported from 11 extant families and 39 extant genera in the Western Hemisphere alone (Mirle and Burnham, 1999
). Fossils of these extant genera and families are to be expected in younger Tertiary sediments of the Western Hemisphere, but to date few determinations of asymmetrically winged fruits from South America have been made (Engelhardt, 1895
; Burnham, 1995
). To our knowledge, no similar compilation of other types of extant winged fruits (symmetrically winged samaras, helicopters, etc.) of the Western Hemisphere has yet been published. Because of the importance and abundance of winged fruits in the fossil record, such a compilation would be useful.
During fieldwork in the Ecuadorian valleys of Cuenca, Nabon, and Loja, fossil fruits belonging to the angiosperm family Anacardiaceae were recovered. A sufficient quantity of fruits now has been collected to adequately characterize the fruits, and the material is described here.
The Anacardiaceae (poison ivy, cashew, or sumac family) is a member of the order Sapindales, closest to Burseraceae, but also allied to Rutaceae, Meliaceae, and Sapindaceae (Zomlefer, 1994
; Gadek et al., 1996
; Pell and Urbatsch, 2001
; Judd et al., 2002
). The Anacardiaceae are characterized by usually alternate, often pinnately compound leaves, resin canals in the bark and larger veins, and three-carpellate ovaries, which are often reduced to a single locule with a single seed. In spite of the frequently irritant resin (Mitchell, 1990
), the family is probably best known for its production of the edible fruits or seeds of pistachios, mangos, and cashews. Anacardiaceae are pantropical in distribution, with well known Rhus and Toxicodendron extending into temperate areas (Zomlefer, 1994
).
Here we describe a new fossil species of asymmetrically winged fruit assigned to the genus Loxopterygium (Anacardiaceae) from Ecuador, whose distribution is known only from two small geographic areas in the basins of Cuenca and Loja, Ecuador. The species is the first known record of the genus from the fossil record and contributes to a reconstruction of the vegetation of the Andes Mountains during a critical time of uplift and physiographic change. The new species has also contributed to constraining the temporal relationships among extant members of the genus (Pell and Urbatsch, 2001
; Pennington et al., 2004).
Fossil representatives of Anacardiaceae in Central and South America
Fossil representatives of the Anacardiaceae are frequently listed in paleobotanical literature, but few recently confirmed members of the family can be cited. It is beyond the scope of this report of a new species of fossil fruit to revise the fossil representatives of the entire family. However, we briefly review here citations of various plant organs assigned to the family that have been previously reported from South America, Central America, and the Caribbean region. In South America there are numerous unrevised citations of Anacardium fruits by E. W. Berry (1924a
, b
, 1927a
, 1929a
, b
). These fruits and seed casts are generally reniform, calcified specimens with a thick ligneous endocarp ("shell" of Berry), and are attributed to Eocene and Oligocene sediments. In addition, Reid (1933)
described a new genus, Colombicarpum, a biloculate endocarp similar to the modern drupaceous Tapirira from the Tertiary of Colombia.
With respect to leaves, in 1927 Berry stated, "The genus Anacardites of Saporta affords a convenient resting place for fossil leaves of the Anacardiaceae of doubtful generic identity" (Berry, 1927b
). In fact, much of the foliage attributed to the Anacardiaceae may not belong in the family at all and a thorough revision of the fossil members of the family is in order. Between 1895 and 1939 descriptions were published by various authors of leaves or leaflets of about 15 species placed in the genera Anacardites, Duvaua (= Schinus), Metopium, Roophyllum, Spondias, Schinus, Schinopsis, and Tapirira from Colombia, Ecuador, Brasil, Peru, Bolivia, and Argentina (largely by E. W. Berry but also by Engelhardt [1895]
and Hoffman [1931]
). Schinopsis patagonica, S. morongifolia and S. balansiformis were reported from Eocene deposits of Argentina, and may be the oldest record of this genus, although those records (Berry, 1925
, 1938) have not been confirmed as valid records of that genus (which bears asymmetrically winged fruits) and are simply relisted by Romero (1986)
. Recently, a reliable reference to leaves of two species of Pseudosmodingium from Puebla, Mexico was published (Ramirez et al., 2000
). Gregory-Wodzicki (2002)
reported that two species of undescribed Anacardiaceae make up 48% of foliage specimens from the Miocene Jakokkota flora of Bolivia.
Various genera of fossil wood have been described in the literature on South and Central America (Anacardioxylon from the West Indies: Hollick, 1924
; Schinopsixylon from the Pleistocene of Argentina: Brea, 1999
), but nothing has been reported as far as we are aware from northern South America.
Form genera used in the palynological literature (especially those used for purely stratigraphic purposes) make searching for family-level pollen records more difficult than a standard taxonomic search. Records of pollen assignable to Anacardiaceae are certainly present in the oil company literature, however there are two common taxonomic form names for pollen types of the Anacardiaceae: Tricolporopollenites pseudocingulum and Striatricolporites gamerroi (Muller, 1981
; Romero and Castro, 1986
). In Southern Argentina (Chubut and Santa Cruz Provinces) S. gamerroi appears as some of the earliest records of presumed Anacardiaceae pollen in Eocene and Paleocene sediments (Archangelsky, 1973
; Romero and Castro, 1986
; Romero, 1993
). The apparently oldest confirmed record of pollen assigned to an extant Anacardiaceous genus is that of Metopium from the Miocene of Cuba (Graham, 2003
), while Tapirira pollen is reported from the late Miocene of the Cordillera Oriental by Wijninga (1996)
.
The fossil record of asymmetric samaras in northern South America
Although many winged fruits can be found in museum collections of fossils from various localities in northern South America, a surprising lack of information in published literature exists. Only two species of asymmetrically winged samaras from Bolivia, Peru, Ecuador, and Colombia are known to have been published since 1895 (Banisteria aceroides Engelhardt and Tipuana ecuatoriana Burnham). There are no known reports of fossils of the genus Loxopterygium. The species of "Banisteria" described by Engelhardt (1895)
was reconfirmed by Berry (1929c)
. Unfortunately the plate figuring this specimen published by Engelhardt in 1895 apparently reversed the figure numbers of two genera and four figures, so text reference to Banisteria cites the two figures of Hiraea instead of Banisteria, and vice versa. Careful reading of the German text certainly indicates the error. Extant species of the genus "Banisteria" were reassigned to the genera Heteropterys and Banisteriopsis (Gates, 1982
; Mabberley, 1997
) subsequent to Engelhardt's work, and the species of extant Banisteria to which Engelhardt compared his fossil specimen, Banisteria adamantium, is now known as Banisteriopsis schizoptera (Gates, 1982
). We believe this specimen is appropriately placed in the Malpighiaceae based on inspection of the drawing in Engelhardt's monograph.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
). Sediments enclosing the fossils are fine clays and silts, indicative of quiet water, lacustrine deposition, but at most outcrops small-scale soft sediment deformation indicates that sedimentation rate was fairly high (estimated at 1 mm/year by Steinmann, 1997
; reported in Hungerbühler et al., 2002
).
One additional specimen was recovered from very fine lacustrine diatomitic shales in the San Cayetano Formation in the Loja Basin (3°59'27.8'' S, 79°11'25.5'' W), about 140 km to the south of the localities in Azogues. The Loja locality lies at approximately 2160 m. Hungerbühler et al. (2002)
also interpreted the quiet water facies of the San Cayetano Formation as a "freshwater lake situated in a tropical environment at low elevation." The fossils are derived from the Siltstone Member, dated at 10.7 ± 1.6 to 10.0 ± 1.4 Ma (Hungerbühler et al., 2002
). Thus the fossil leaf bearing deposits from the two basins are roughly contemporary, as far as we can determine, and assignable to the Middle Miocene.
Specimens of three extant species of Loxopterygium (Figs. 1–3) were examined at the University of Michigan herbarium (MICH), as well as specimens on loan from the Field Museum of Natural History in Chicago (F), New York Botanical Garden (NYBG), and Missouri Botanical Garden (MO). Specimens bearing mature and immature fruits were examined for the extant species L. grisebachii, L. huasango, and L. sagotii. Representative fruiting specimens of species of Schinopsis (Anacardiaceae), Banisteriopsis, Heteropterys, Stigmaphyllon (Malpighiaceae), Tipuana, Machaerium, Nissolia (Fabaceae), Securidaca (Polygalaceae), Seguieria (Phytolaccaceae), Phyllostylon (Ulmaceae), Acer, Serjania, Thouinia, Thinouia, Thouindium (Sapindaceae), as well as winged seeds of Anthodon (Celastraceae) and Cedrela (Meliaceae) are compared to the fossil.
|
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
The fossil specimens represent fruits with a single proximal locule and a distal wing, expanding from the side of the ovary wall. The remnant of the stigma is present medially on the backbone of the wing. In two specimens (EPN 885 and 1054) the stigma bears two minute lobes (Figs. 4–6). The pedicel of the fruit and calyx remnant are preserved at the proximal end of the locule, indicating orientation of the fruit, relative to the parent plant. The fruits range in length from 9.0 to 16.0 mm from pedicel attachment to wing tip. At their broadest point, the fruits are 2.6–5.5 mm wide. The locules are oblong in shape, rounded proximally and distally, ranging in length from 4.0 to 6.0 mm and in width from 2.0 to 4.0 mm. The boundary between the locule and the wing is clearly marked in most specimens due to crushing of the originally spherical, resistant endocarp. During fossilization, fracturing of the wall of the locule results in a quadrangular pattern over the locule wall in some specimens. This pattern is entirely absent from the wing of the fruit. Obliquely parallel venation is visible on the locule. A strong vein, originating from the attachment point and running obliquely to the backbone, divides the locule into two parts (the side close to the backbone and the side away from the backbone). This vein, in well-preserved specimens, amplifies the difference in the spacing of the primary veins on the locule wall of these two sectors. On the side of the locule close to the backbone, the veins are typically more widely spaced (with the widest spacing up to 
0.5 mm) than on the side away from the backbone. The area between the veins of the locule on the side away from backbone is devoid of the quadrangular pattern.
The wing bears angled primary veins, which are parallel to the shape of the backbone and parallel to one another. These veins originate at the proximal portion of the locule and can extend to the wing margin. The veins are densely distributed near the backbone of the wing and spread laterally as they approach the distal edge of the wing. The primary veins terminate anywhere from two-thirds of the length to the wing tip up to the end of the wing tip. These veins spread out and diminish in thickness as they approach the wing margin. The veins are particularly faint on the side of the wing opposite the backbone. Only rarely do the main wing veins end in the occasional small serrations on the wing tip. The primary veins do not anastomose, and primary vein branching is rare in the fossil specimens (generally no more than 2–4 primary veins branch per specimen). The fossils have a smooth margin along the wing, with the exception of the wing tip. At the wing tip, the margin varies from erose to serrate.
Holotype
EPN 1054, Fig. 4, Locality RJB 9602 ("Azogues View"), Cuenca Basin, Departamento de Cuenca, Ecuador.
Other specimens
Accession numbers of Escuela Politecnica Nacional del Ecuador (EPN)—Cuenca Basin: 65, 67, 74, 118, 119, 120, 770, 776, 822, 884, 885, 938, 988, 989, 1005, 1238, 1254, 1264; Loja Basin: EPN 504. All specimens are permanently housed at the Escuela Politecnica Nacional del Ecuador in Quito, Ecuador.
Etymology
The epithet refers to the small neighborhood, Bolivia La Playa, near the town of Azogues, from which the majority of the fossil specimens were collected in the Cuenca Basin.
Discussion of Loxopterygium laplayense n. sp
We have summarized the important fruit characters of similar-appearing modern genera bearing asymmetrically winged samaras (both fruits and seeds) from the western hemisphere in Table 1. The distinctive characters of the fossil are the medially placed stigma remnant on the backbone of the wing (Figs. 5, 6), the small size (<2 cm in total length), the remnant calyx at the proximal end of the locule, and the frequently erose to serrate wing tip (Figs. 4–6). This combination of characters placed the specimens in the genus Loxopterygium of the Anacardiaceae (Table 1).
|
|
; Rizzini, 1975
; Mitchell and Daly, 1991
; Pennington et al., 2004), the fruits of which have been compared to the fossil fruits from Ecuador. Measurements and characteristics of all three modern species based on study of herbarium specimens are summarized in Table 2. The fossil is easily distinguished from L. sagotii by a number of characteristics (particularly size and wing venation; Table 2, Fig. 1). Two modern species of Loxopterygium are very similar in fruit morphology to the fossil and we find it difficult to consistently distinguish between these two modern species (L. huasango and L. grisebachii) based on fruit characteristics alone (Figs. 2, 3). Although L. huasango has a tendency to have a lower length-to-width ratio, and a stigma placed further distally on the backbone than L. grisebachii, neither the length-to-width ratios of the two species nor the stigma position (as measured by the proportion of total fruit length) are statistically different among the specimens studied. However, L. huasango has a consistently and distinctly serrate wing tip, while specimens of L. grisebachii more often have an erose wing tip, rather than serrate. In addition, the pedicel is often dispersed with the fruit in L. grisebachii, whereas the pedicel remains attached to the parent plant in L. huasango. The number of specimens studied for these observations and measurements were limited by collections available (2–6 fruits/collection drawn from three to seven independent collections per species).
|
Over 1200 specimens of leaves, flowers and fruits have been collected from deposits in the basins of Cuenca, Loja, and Nabon to date. Thus far no leaves that bear strong similarities to leaves of modern Loxopterygium have been recovered. A few partial leaves do seem to bear a resemblance to Loxopterygium, but these leaves are incomplete and without better material, it would not be possible to determine whether they are related to the fruits described here.
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
. Two of the species they map are not currently recognized as distinct species of Loxopterygium (Pennington et al., 2004). However, at the continental scale, it is clear that there are two Andean species (L. grisebachii and L. huasango) and one Venezuelan-Guyanan species (L. sagotii). The known distributional data for these three species, as recorded in floras and from herbarium specimens is listed in Table 3. Two species are distributed in upland and lowland seasonally dry forests of the Andes and coastal regions of northern South America. A third species is found in moist primary forests of Venezuela, Suriname, and Guyana. Because the genus occurs in both wet and dry tropical forests, a generic determination alone is not definitive for inference of climatic distribution of the fossil species. However, because the fossil species reported here is clearly more similar to the two modern seasonally dry forest species and distinct from the modern rainforest species, it is proposed that the fossil species is representative of seasonally dry forest, rather than moist forest. In addition the ecological distributions of species of other recognizable genera in the Miocene flora from Ecuador (Tipuana, Cedrela, Serjania, Ruprechtia) are consistent with a tropical dry forest interpretation. The elevational range of L. huasango and L. grisebachii is from 0 to 2100 m, with L. grisebachii more commonly found above 1000 m than L. huasango.
|
Today in some forested areas of Tumbes, Peru, Loxopterygium dominates a dry tropical forest woodland (Gentry, 1995
). It is remarkable that the species of Loxopterygium laplayense represented by the fossils described here can be placed so readily within a small extant lineage of dry forest species. The lack of morphological change demonstrated by the modern dry forest species, at least in terms of fruit morphology, suggests that habitat similar to that in which these species are successful today has been in existence in the same area of the Andes for as much as 10 million years. The sedimentary deposits in the Loja Basin also bear fruits of Tipuana ecuatoriana (Fabaceae), which can scarcely be distinguished from the modern Tipuana tipu that occurs in the dry forests of Bolivia and Argentina today (Burnham, 1995
). The record of Tipuana, as well as Loxopterygium, indicate that we still know very little about the rate of morphological change in South American plant genera. The use of angiosperm fossils to calibrate well-constrained molecular phylogenies appears to be a fruitful means of constraining rates of morphological evolution in plants.
|
FOOTNOTES |
|---|
2 E-mail: rburnham{at}umich.edu
|
LITERATURE CITED |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Barkley F. A. 1962 Anacardiaceae: Rhoideae: Loxopterygium. Lloydia 25: 109-122[ISI]
Berry E. W. 1924a An Oligocene cashew nut from South America. American Journal of Science 8: 123-126[ISI]
Berry E. W. 1924b New Tertiac species of Anacardium and Vantanea from Colombia. Pan-American Geologist 42: 259-262
Berry E. W. 1925 A Miocene flora from Patagonia. John Hopkins University Studies in Geology 6: 182-252
Berry E. W. 1927a Petrified fruits and seeds from Oligocene of Peru. Pan-American Geologist 47: 121-133
Berry E. W. 1927b Miocene plants from southern Mexico. Proceedings of the United States National Museum 62: 1-27
Berry E. W. 1929a Early Tertiary fruits and seeds from Belen, Peru. John Hopkins University Studies in Geology 10: 137-176
Berry E. W. 1929b Fossil fruits in the Ancon Sandstone of Ecuador. Journal of Paleontology 3: 298-301
Berry E. W. 1929c The fossil flora of the Loja Basin in southern Ecuador. John Hopkins Studies in Geology 10: 79-135
Berry E. W. Tertiary flora from the Río Pichileufu, Argentina. Geological Society of America Special Paper 12: 1-149
Brea M. 1999 Leños fósiles de Anacardiaceeae y Mimosaceae de la formación El Palmar (Pleistoceno superior), departamento de Concordia, provincia de Entre Ríos, Argentina. Ameghiana 36: 63-69
Burnham R. J. 1995 A new species of winged fruit from the Miocene of Ecuador: Tipuana ecuatoriana (Leguminosae). American Journal of Botany 82: 1599-1607[CrossRef][ISI]
Englehardt H. 1895 Uber neue Tertiärpflanzen Süd Amerikas. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft Band 19: 1-47
Gadek P. A. E. S. Fernando C. J. Quinn S. B. Hoot T. Terrazas M. C. Sheahan M. W. Chase 1996 Sapindales: molecular delimitation and infraordinal groups. American Journal of Botany 83: 802-811[CrossRef][ISI]
Gates B. 1982 Banisteriopsis, Diplopterys (Malpighiaceae). Flora Neotropica Monograph 30: 1-237
Gentry A. H. 1995 Diversity and floristic composition of neotropical dry forests. In S. H. Bullock, H. A. Mooney, and E. Medina [eds.], Seasonally dry tropical forests, 146–194. Cambridge University Press, Cambridge, UK
Graham A. 2003 Historical phytogeography of the Greater Antilles. Brittonia 55: 357-383[CrossRef][ISI]
Gregory-Wodzicki K. M. 2002 Late Miocene subtropical-dry flora from the northern Altiplano, Bolivia. Palaeogeography, Palaeoclimatology, Palaeoecology 180: 331-348[CrossRef]
Hoffman A. D. 1931 Miocene plants from Betijoque, Venezuela. Master's thesis, University of Chicago, Chicago, Illinois, USA
Hollick A. 1924 A review of the fossil flora of the West Indies, with descriptions of new species. New York Botanical Garden Bulletin 12: 259-323
Hungerbühler D. M. Steinmann W. Winkler D. Seward A. Egüez D. Peterson U. Helg C. Hammer 2002 Neogene stratigraphy and Andean geodynamics of southern Ecuador. Earth Science Reviews 57: 75-124
Judd W. S. C. S. Campbell E. A. Kellogg P. F. Stevens M. J. Donoghue 2002 Plant systematics; a phylogenetic approach, 2nd ed. Sinauer, Sunderland, Massachusetts, USA
Mabberley D. J. 1997 The plant book: a portable dictionary of the vascular plants. Cambridge University Press, Cambridge, UK
Magallón-Puebla S. S. R. S. Cevallos-Ferriz 1994 Eucommia constans n. sp. fruits from Upper Cenozoic strata of Puebla, Mexico— morphological and anatomical comparison with Eucommia ulmoides Oliver. International Journal of Plant Sciences 155: 80-95[CrossRef][ISI]
Manchester S. R. L. Hably 1997 Revision of "Abelia" fruits from the Paleogene of Hungary, Czech Republic and England. Review of Palaeobotany and Palynology 96: 231-240[CrossRef]
McClain A. M. S. R. Manchester 2003 Dipteronia (Sapindaceae) from the Tertiary of North America and implications for the phytogeographic history of the Aceroideae. American Journal of Botany 88: 1316-1325[CrossRef]
Mirle C. R. J. Burnham 1999 A key to asymmetrically winged fruits from the Western Hemisphere. Brittonia 51: 1-14[CrossRef][ISI]
Mitchell J. D. 1990 The poisonous Anacardiaceae genera of the world. Advances in Economic Botany 8: 103-129
Mitchell J. D. D. C. Daly 1991 Cyrtocarpa Kunth (Anacardiaceae) in South America. Annals of the Missouri Botanical Garden 78: 184-189[CrossRef][ISI]
Muller J. 1981 Fossil pollen records of extant angiosperms. The Botanical Review 47: 1-146
Pell S. K. L. Urbatsch 2001 Tribal relationships and character evolution in the cashew family (Anacardiaceae): inferences from three regions of the chloroplast genome. Botany 2001: Plants and People, Albuquerque: 132 (Abstract)
Pennington R. T. M. Lavin D. E. Prado C. A. Pendry S. K. Pell C. A. Butterworth 2004 Historical climate change and speciation: neotropical seasonally dry forest plants show patterns of both Tertiary and Quaternary diversification. Philosophical Transactions of the Royal Society, Biological Sciences 359: 515-537
Prado D. E. P. E. Gibbs 1993 Patterns of species distributions in the dry seasonal forests of South America. Annals of the Missouri Botanical Garden 80: 902-927[CrossRef][ISI]
Ramirez J. L. S. R. S. Cevallos-Ferriz A. Silva-Pineda 2000 Reconstruction of the leaves of two new species of Pseudosmodingium (Anacardiaceae) from Oligocene strata of Puebla, Mexico. International Journal of Plant Sciences 161: 509-519[CrossRef][ISI][Medline]
Reid E. M. 1933 Note on some fossil fruits of Tertiary age from Colombia, South America. Revue de Geographie Physique 6: 209-216
Rizzini C. T. 1975 Novitates florae Brasiliensis. Leandra 6: 40-43
Romero E. J. 1986 Paleogene phytogeography and climatology of South America. Annals of the Missouri Botanical Garden 73: 449-61
Romero E. J. 1993 South American Paleofloras. In P. Goldblatt [ed.], Biological relationships between Africa and South America, 62–85. Yale University Press, New Haven, Connecticut, USA
Romero E. J. M. T. Castro 1986 Material fúngico y granos de polen de Angiospermas de la formación Río Turbio (Eoceno) Provincia de Santa Cruz, República Argentina. Ameghiniana 23: 101-118
Steinmann M. 1997 The Cuenca basin of southern Ecuador: tectono-sedimentary history and the Tertiary Andean evolution. Ph.D. dissertation, Institute of Geology, ETH Zurich, Switzerland
Wang Y. S. R. Manchester 2000 Chaneya, a new genus of winged fruit from the Tertiary of North America and eastern Asia. International Journal of Plant Sciences 161: 167-178[CrossRef][ISI][Medline]
Wijninga V. M. 1996 Neogene ecology of the Salto de Tequendama site (2475m altitude, Cordillera Oriental, Colombia): the paleobotanical record of montane and lowland forests. Review of Palaeobotany and Palynology 92: 97-156[CrossRef]
Zomlefer W. B. 1994 Guide to flowering plant families. The University of North Carolina Press, Chapel Hill, North Carolina, USA
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
