Leaf and inflorescence evidence for near-basal Araceae and an unexpected diversity of other monocots from the late Early Cretaceous of Spain

References

• Aguilar, M. J., Ramírez del Pozo, J. & Oriol-Riba, A. 1971. Algunas precisiones sobre la sedimentación y la paleoecología del Cretácico Inferior en la zona de Utrillas-Villaroya de los Pinares (Teruel). Estudios Geológicos, 27, 497–512.
   Google Scholar
• Amato, J. M., Mack, G. H., Jonell, T. N., Seager, W. R. & Upchurch, G. R. 2017. Onset of the Laramide orogeny and associated magmatism in southern New Mexico based on U-Pb geochronology. Geological Society of America Bulletin, 129, 1209–1226.
   Web of Science ®Google Scholar
• APG [Angiosperm Phylogeny Group] III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Botanical Journal of the Linnean Society, 161, 105–121.
   Web of Science ®Google Scholar
• Berry, E. W. 1930. Revision of the lower Eocene Wilcox flora of the southeastern states. United States Geological Survey Professional Paper, 156, 1–196.
   Google Scholar
• Bogner, J., Hoffmann, G. L. & Aulenback, K. R. 2005. A fossilized aroid infructescence, Albertarum pueri gen.nov. et sp.nov., of Late Cretaceous (Late Campanian) age from the Horseshoe Canyon Formation of southern Alberta, Canada. Canadian Journal of Botany, 83, 591–598.
   Google Scholar
• Bogner, J., Johnson, K. R., Kvaček, Z. & Upchurch, G. R. 2007. New fossil leaves of Araceae from the Late Cretaceous and Paleogene of western North America. Zitteliana, Series A, 47, 133–147.
   Google Scholar
• Brenner, G. J. 1963. The spores and pollen of the Potomac Group of Maryland. Maryland Department of Geology Mines and Water Resources Bulletin, 27, 1–215.
   Google Scholar
• Cabrera, L. I., Salazar, G. A., Chase, M. W., Mayo, S. J., Bogner, J. & Dávila, P. 2008. Phylogenetic relationships of aroids and duckweeds (Araceae) inferred from coding and noncoding plastid DNA. American Journal of Botany, 95, 1153–1165.
   PubMed Web of Science ®Google Scholar
• Calonge, A. 1989. Bioestratigrafía del Cenomaniense de la Cordillera Ibérica por Foraminíferos bentónicos. Unpublished PhD thesis, Universidad Complutense de Madrid, 558 pp.
   Google Scholar
• Canérot, J., Cugny, P., Pardo, G., Salas, R. & Villena, J. 1982. Ibérica central-Maestrazgo. Pp. 273–344 in A. García (ed.) El Cretácico de España. Universidad Complutense de Madrid, Madrid.
   Google Scholar
• Cantino, P. D., Doyle, J. A., Graham, S. W., Judd, W. S., Olmstead, R. G., Soltis, D. E., Soltis, P. S. & Donoghue, M. J. 2007. Towards a phylogenetic nomenclature of Tracheophyta. Taxon, 56, 822–846.
   Web of Science ®Google Scholar
• Coiffard, C. & Mohr, B. A. R. 2015. Lejalia sagenopteroides gen. nov. et comb. nov.: a new tropical member of Araceae from Late Cretaceous strata of northern Gondwana (Jebel Abyad, Sudan). Taxon, 64, 987–997.
   Web of Science ®Google Scholar
• Coiffard, C., Mohr, B. A. R. & Bernardes de Oliveira, M. E. C. 2013. The Early Cretaceous Aroid, Spixiarum kipea gen. et sp. nov., and implications on early dispersal and ecology of basal monocots. Taxon, 62, 997–1008.
   Web of Science ®Google Scholar
• Coiffard, C., Mohr, B. A. R. & Bernardes de Oliveira, M. E. C. 2014. Hexagyne philippiana gen. et sp. nov., a piperalean angiosperm from the Early Cretaceous of northern Gondwana (Crato Formation, Brazil). Taxon, 63, 1275–1286.
   Web of Science ®Google Scholar
• Comes, H. P., Tribsch, A. & Bittkau, C. 2008. Plant speciation in continental island floras as exemplified by Nigella in the Aegean Archipelago. Philosophical Transactions of the Royal Society B, 363, 3083–3096.
   PubMed Web of Science ®Google Scholar
• Conran, J. G., Bannister, J. M., Lee, D. E., Carpenter, R. J., Kennedy, E. M., Reichgelt, T. & Fordyce, R. E. 2015. An update of monocot macrofossil data from New Zealand and Australia. Botanical Journal of the Linnean Society, 178, 394–420.
   Web of Science ®Google Scholar
• Couper, R. A. 1953. Upper Mesozoic and Cainozoic spores and pollen grains from New Zealand. New Zealand Geological Survey Palaeontological Bulletin, 22, 1–77.
   Google Scholar
• Crane, P. R. & Upchurch, G. R. 1987. Drewria potomacensis gen. et sp. nov., an Early Cretaceous member of Gnetales from the Potomac Group of Virginia. American Journal of Botany, 74, 1722–1736.
   Web of Science ®Google Scholar
• Crawford, D. J. & Archibald, J. K. 2017. Island floras as model systems for studies of plant speciation: prospects and challenges. Journal of Systematics and Evolution, 55, 1–15.
   Web of Science ®Google Scholar
• Crepet, W. L. 1978. Investigations of angiosperms from the Eocene of North America: an aroid inflorescence. Review of Palaeobotany and Palynology, 25, 241–252.
   Web of Science ®Google Scholar
• Cúneo N. R., Gandolfo, M. A., Zamaloa, M. C. & Hermsen, E. 2014. Late Cretaceous aquatic plant world in Patagonia, Argentina. PLoS ONE, 9(8), e104749.
   PubMed Web of Science ®Google Scholar
• Cusimano, N., Bogner, J., Mayo, S. J., Boyce, P. C., Wong, S. Y., Hesse, M., Hetterscheid, W. L. A., Keating, R. C. & French, J. C. 2011. Relationships within the Araceae: comparison of morphological patterns with molecular phylogenies. American Journal of Botany, 98, 654–668.
   PubMed Web of Science ®Google Scholar
• Dahlgren, R. M. T. & Clifford, H. T. 1982. The Monocotyledons: A Comparative Study. Academic Press, London, New York, 378 pp.
   Google Scholar
• Dahlgren, R. & Rasmussen, F. N. 1983. Monocotyledon evolution: characters and phylogenetic estimation. Pp. 255–395 in M. K. Hecht, B. Wallace & G. T. Prance (eds) Evolutionary Biology, Volume 16. Plenum, New York.
   Google Scholar
• Dahlgren, R. M. T., Clifford, H. T. & Yeo, P. F. 1985. The Families of the Monocotyledons. Structure, Evolution, and Taxonomy. Springer, Berlin, 520 pp.
   Google Scholar
• Dilcher, D. L. 1974. Approaches to the identification of angiosperm leaf remains. Botanical Review, 40, 1–157.
   Web of Science ®Google Scholar
• Doyle, J. A. 1973. Fossil evidence on early evolution of the monocotyledons. Quarterly Review of Biology, 48, 399–413.
   Web of Science ®Google Scholar
• Doyle, J. A. 2015. Recognising angiosperm clades in the Early Cretaceous fossil record. Historical Biology, 27, 414–429.
   Web of Science ®Google Scholar
• Doyle, J. A. & Endress, P. K. 2010. Integrating Early Cretaceous fossils into the phylogeny of living angiosperms: Magnoliidae and eudicots. Journal of Systematics and Evolution, 48, 1–35.
   Web of Science ®Google Scholar
• Doyle, J. A. & Endress, P. K. 2014. Integrating Early Cretaceous fossils into the phylogeny of living angiosperms: ANITA lines and relatives of Chloranthaceae. International Journal of Plant Sciences, 175, 555–600.
   Web of Science ®Google Scholar
• Doyle, J. A. & Robbins, E. I. 1977. Angiosperm pollen zonation of the continental Cretaceous of the Atlantic Coastal Plain and its application to deep wells in the Salisbury Embayment. Palynology, 1, 43–78.
   Google Scholar
• Doyle, J. A., Endress, P. K. & Upchurch, G. R. 2008. Early Cretaceous monocots: a phylogenetic evaluation. Acta Musei Nationalis Pragae, Series B, Historia Naturalis, 64(2–4), 59–87.
   Google Scholar
• Dumortier, B. C. 1829. Analyse des Familles des Plantes. Casterman, Tournay, 104 pp.
   Google Scholar
• Endress, P. K. & Doyle, J. A. 2007. Floral phyllotaxis in basal angiosperms: development and evolution. Current Opinion in Plant Biology, 10, 52–57.
   PubMed Web of Science ®Google Scholar
• Ertl, P. O. 1932. Vergleichende Untersuchungen über die Entwicklung der Blattnervatur der Araceen. Flora, 126, 115–248.
   Google Scholar
• Fontaine, W. M. 1889. The Potomac or younger Mesozoic flora. United States Geological Survey Monographs, 15, 1–377.
   Google Scholar
• Friis, E. M., Eklund, H., Pedersen, K. R. & Crane, P. R. 1994. Virginianthus calycanthoides gen. et sp. nov. –– a calycanthaceous flower from the Potomac Group (Early Cretaceous) of eastern North America. International Journal of Plant Sciences, 155, 772–785.
   Web of Science ®Google Scholar
• Friis, E. M., Crane, P. R. & Pedersen, K. R. 1997. Anacostia, a new basal angiosperm from the Early Cretaceous of North America and Portugal with trichotomocolpate/monocolpate pollen. Grana, 36, 225–244.
   Web of Science ®Google Scholar
• Friis, E. M., Pedersen, K. R. & Crane, P. R. 2000. Fossil floral structures of a basal angiosperm with monocolpate, reticulate-acolumellate pollen from the Early Cretaceous of Portugal. Grana, 39, 226–239.
   Web of Science ®Google Scholar
• Friis, E. M., Pedersen, K. R. & Crane, P. R. 2004. Araceae from the Early Cretaceous of Portugal: evidence on the emergence of monocotyledons. Proceedings of the National Academy of Sciences of the USA, 101, 16565–16570.
   PubMed Web of Science ®Google Scholar
• Friis, E. M., Pedersen, K. R. & Crane, P. R. 2006. Cretaceous angiosperm flowers: innovation and evolution in plant reproduction. Palaeogeography, Palaeoclimatology, Palaeoecology, 232, 251–293.
   Web of Science ®Google Scholar
• Friis, E. M., Pedersen, K. R. & Crane, P. R. 2010. Diversity in obscurity: fossil flowers and the early history of angiosperms. Philosophical Transactions of the Royal Society of London B, 365, 369–382.
   PubMed Web of Science ®Google Scholar
• Friis, E. M., Crane, P. R. & Pedersen, K. R. 2011. Early Flowers and Angiosperm Evolution. Cambridge University Press, Cambridge, UK, 585 pp.
   Google Scholar
• Gallego, J., Gandolfo, M. A., Cúneo, N. R. & Zamaloa, M. C. 2014. Fossil Araceae from the Upper Cretaceous of Patagonia, Argentina, with implications on the origin of free-floating aquatic aroids. Review of Palaeobotany and Palynology, 211, 78–86.
   Web of Science ®Google Scholar
• Gandolfo, M. A., Nixon, K. C. & Crepet, W. L. 2000. Monocotyledons: a review of their Early Cretaceous record. Pp. 44–51 in K. L. Wilson & D. A. Morrison (eds) Monocots: Systematics and Evolution. CSIRO Publishing, Collingwood, Australia.
   Google Scholar
• García, A., Segura, M., Calonge, A. & Carenas, B. 1989. Unidades estratigráficas para la organización de la sucesión sedimentaria de la plataforma Albiense-Cenomaniense de la Cordillera Ibérica. Revista de la Sociedad Geológica de España, 2, 303–333.
   Google Scholar
• Gomez, B., Coiffard, C., Sender, L. M., Martín-Closas, C., Villanueva-Amadoz, U. & Ferrer, J. 2009. Klitzschophyllites, aquatic basal eudicots (Ranunculales?) from the upper Albian (Lower Cretaceous) of north-eastern Spain. International Journal of Plant Sciences, 170, 1075–1085.
   Web of Science ®Google Scholar
• Grayum, M. H. 1987. A summary of evidence and arguments supporting the removal of Acorus from the Araceae. Taxon, 36, 723–729.
   Web of Science ®Google Scholar
• Grayum, M. H. 1990. Evolution and phylogeny of the Araceae. Annals of the Missouri Botanical Garden, 77, 628–697.
   Web of Science ®Google Scholar
• Harris, T. M. 1932. The fossil flora of Scoresby Sound, West Greenland. Meddelelser om Grønland, 85(3), 1–112.
   Google Scholar
• Herman, A. B. & Kvaček, J. 2010. Late Cretaceous Grünbach Flora of Austria. Naturhistorisches Museum Wien, Vienna, 216 pp.
   Google Scholar
• Hickey, L. J. 1973. Classification of the architecture of dicotyledonous leaves. American Journal of Botany, 60, 17–33.
   Web of Science ®Google Scholar
• Hickey, L. J. & Peterson, R. K. 1978. Zingiberopsis, a fossil genus of the ginger family from Late Cretaceous to early Eocene sediments of Western Interior North America. Canadian Journal of Botany, 56, 1136–1152.
   Google Scholar
• Hofmann, C.-C. & Zetter, R. 2010. Upper Cretaceous sulcate pollen from the Timerdyakh Formation, Vilui Basin (Siberia). Grana, 49, 170–193.
   Web of Science ®Google Scholar
• Iles, W. J. D., Smith, S. Y. & Graham, S. W. 2013. A well-supported phylogenetic framework for the monocot order Alismatales reveals multiple losses of the plastid NADH dehydrogenase complex and a strong long-branch effect. Pp. 1–28 in P. Wilkin & S. J. Mayo (eds) Early Events in Monocot Evolution. Cambridge University Press, Cambridge, UK.
   Google Scholar
• Iles, J. D., Smith, S. Y., Gandolfo, M. A. & Graham, S. W. 2015. Monocot fossils suitable for molecular dating analyses. Botanical Journal of the Linnean Society, 178, 346–374.
   Web of Science ®Google Scholar
• Joppa, L. N., Roberts, D. L. & Pimm, S. L. 2010. How many species of flowering plants are there? Proceedings of the Royal Society B, 278, 554–559.
   PubMed Web of Science ®Google Scholar
• Joppa, L. N., Roberts, D. L., Myers, N. & Pimm, S. L. 2011. Biodiversity hotspots house most undiscovered plant species. Proceedings of the National Academy of Sciences of the USA, 108, 13171–13176.
   PubMed Web of Science ®Google Scholar
• Jussieu, A. L. de. 1789. Genera Plantarum. Paris, lxxii + 498 pp.
   Google Scholar
• Kaplan, D. R. 1970. Comparative foliar histogenesis in Acorus calamus and its bearing on the phyllode theory of monocotyledonous leaves. American Journal of Botany, 57, 331–361.
   Web of Science ®Google Scholar
• Kauffman, E. G., Upchurch, G. R. & Nichols, D. J. 1990. The Cretaceous–Tertiary boundary interval at South Table Mountain, near Golden, Colorado. Pp. 365–392 in E. G. Kauffman & O. H. Walliser (eds) Extinction Events in Earth History. Springer, Berlin.
   Google Scholar
• Kaul, R. B. 1976. Anatomical observations on floating leaves. Aquatic Botany, 2, 215–234.
   Google Scholar
• Keating, R. C. 2002. Anatomy of the Monocotyledons IX. Acoraceae and Araceae. Clarendon Press, Oxford, 327 pp.
   Google Scholar
• Kedves, M. & Diniz, F. 1981. Protobrevaxones, a new pollen group for the first Brevaxones form-genera from the upper Cenomanian of Portugal. Acta Botanica Academiae Scientiarum Hungaricae, 27, 383–402.
   Google Scholar
• Kerp, H. & Bomfleur, B. 2011. Photography of plant fossils – new techniques, old tricks. Review of Palaeobotany and Palynology, 166, 117–151.
   Web of Science ®Google Scholar
• Krassilov, V. A. 1984. New paleobotanical data on origin and early evolution of angiospermy. Annals of the Missouri Botanical Garden, 71, 577–592.
   Web of Science ®Google Scholar
• Krassilov, V. & Kodrul, T. 2009. Reproductive structures associated with Cobbania, a floating monocot from the Late Cretaceous of the Amur Region, Russian Far East. Acta Palaeobotanica, 49, 233–251.
   Google Scholar
• Kryshtofovich, A. 1929. The oldest angiosperms in the Cretaceous of Asia and other contributions to the Mesozoic flora of the maritime province, Siberia. American Journal of Science, 1, 519–525.
   Google Scholar
• Kunzmann, L. 2012. Early Oligocene riparian and swamp forests with a mass occurrence of Zingiberoideophyllum (extinct Zingiberales) from Saxony, central Germany. Palaios, 27, 765–778.
   Web of Science ®Google Scholar
• Kvaček, J. & Herman, A. B. 2004. Monocotyledons from the early Campanian (Cretaceous) of Grünbach, Lower Austria. Review of Palaeobotany and Palynology, 128, 323–353.
   Web of Science ®Google Scholar
• Kvaček, J. & Smith, S. Y. 2015. Orontiophyllum, a new genus for foliage of fossil Orontioideae (Araceae) from the Cretaceous of central Europe. Botanical Journal of the Linnean Society, 178, 489–500.
   Web of Science ®Google Scholar
• Lejal-Nicol, A. 1981. Nouvelles empreintes de la ‘‘Lingula Shale Unit’’ dans la région d’Abu Ballas (Egypte). Pp. 15–27 in Comptes Rendus du 106e Congrès national des Sociétés savantes, Perpignan, Section des Sciences. Bibliothèque Nationale, Paris.
   Google Scholar
• Lendínez, A., Ruíz, V. & Carls, P. 1989. Memoria del Mapa Geológico de España a Escala 1:5000, n° 466 (Moyuela). Instituto Geológico y Minero de España, Madrid, 116 pp.
   Google Scholar
• Les, D. H. & Schneider, E. L. 1995. The Nymphaeales, Alismatidae, and the theory of an aquatic monocotyledon origin. Pp. 23–42 in P. J. Rudall, P. J. Cribb, D. F. Cutler & C. J. Humphries (eds) Monocotyledons: Systematics and Evolution. Volume 1. Royal Botanic Gardens, Kew.
   Google Scholar
• Lima, F. J., Saraiva, A. A. F., Silva, M. A. P., Bantim, R. A. M. & Sayão, J. M. 2014. A new angiosperm from the Crato Formation (Araripe Basin, Brazil) and comments on the Early Cretaceous monocotyledons. Anais da Academia Brasileira de Ciências, 86, 1657–1672.
   PubMed Web of Science ®Google Scholar
• Luo, Y., Ma, P. F., Li, H. T., Yang, J. B., Wang, H. & Li, D. Z. 2016. Plastid phylogenomic analyses resolve Tofieldiaceae as the root of the early diverging monocot order Alismatales. Genome Biology and Evolution, 8, 932–945.
   PubMed Web of Science ®Google Scholar
• Maddison, D. R. & Maddison, W. P. 2003. MacClade 4: Analysis of Phylogeny and Character Evolution. Version 4.06. Sinauer Associates, Sunderland, Massachusetts.
   Google Scholar
• Maddison, W. P. & Maddison, D. R. 2011. Mesquite: a Modular System for Evolutionary Analysis. Version 2.75. Updated at: http://mesquiteproject.org.
   Google Scholar
• Mayo, S. J., Bogner, J. & Boyce, P. C. 1997. The Genera of Araceae. Royal Botanic Gardens, Kew, 370 pp.
   Google Scholar
• Mohr, B. A. R. & Rydin, C. 2002. Trifurcatia flabellata n. gen. n. sp., a putative monocotyledon angiosperm from the Lower Cretaceous Crato Formation (Brazil). Mitteilungen aus dem Museum für Naturkunde der Humboldt-Universität Berlin, Geowissenschaftliche Reihe, 5, 335–344.
   Google Scholar
• Mohr, B. A. R., Bernardes-de-Oliveira, M. E. C., Barale, G. & Ouaja, M. 2006. Palaeogeographic distribution and ecology of Klitzschophyllites, an Early Cretaceous angiosperm in southern Laurasia and northern Gondwana. Cretaceous Research, 27, 464–472.
   Web of Science ®Google Scholar
• Nauheimer, L., Metzler, D. & Renner, S. S. 2012. Global history of the ancient monocot family Araceae inferred with models accounting for past continental positions and previous ranges based on fossils. New Phytologist, 195, 938–950.
   PubMed Web of Science ®Google Scholar
• Pant, D. D. & Kidwai. P. F. 1966. Structure of leaves and stomatal ontogeny in some Pandanales and Spathiflorae. Senckenbergiana Biologica, 47, 309–331.
   Google Scholar
• Pardo, G. & Villena, J. 1979. Estudio sedimentológico de las Arenas de Utrillas, en las cuencas de Utrillas y Estercuel. Estudios Geológicos, 35, 645–650.
   Google Scholar
• Peppe, D. J., Erickson, J. M. & Hickey, L. J. 2007. Fossil leaf species from the Fox Hills Formation (Upper Cretaceous: North Dakota, USA) and their paleogeographic significance. Journal of Paleontology, 81, 550–567.
   Web of Science ®Google Scholar
• Pole, M. 1999. Latest Albian–earliest Cenomanian monocotyledonous leaves from Australia. Botanical Journal of the Linnean Society, 129, 177–186.
   Web of Science ®Google Scholar
• Prabhakar, M. 2004. Structure, delimitation, nomenclature and classification of stomata. Acta Botanica Sinica, 46, 242–252.
   Google Scholar
• Rudall, P. J., Chen, E. D. & Cullen, E. 2017. Evolution and development of monocot stomata. American Journal of Botany, 104, 1122–1141.
   PubMed Web of Science ®Google Scholar
• Rydin, C., Mohr, B. & Friis, E. M. 2003. Cratonia cotyledon gen. et sp. nov.: a unique Cretaceous seedling related to Welwitschia. Proceedings of the Royal Society B, 270(Suppl. 1), S29–S32.
   PubMedGoogle Scholar
• Schröder, R. & Neumann, M. (eds). 1985. Les grands Foraminifères du Crétacé moyen de la région méditerranénne. Geobios, mémoire spécial, 7, 1–161.
   Google Scholar
• Sender, L. M., Villanueva-Amadoz, U., Diez, J. B., Sánchez-Pellicer, R., Bercovici, A., Pons, D. & Ferrer, J. 2012. A new uppermost Albian flora from Teruel province, Northeastern Spain. Geodiversitas, 34, 373–397.
   Web of Science ®Google Scholar
• Sender, L. M., Doyle, J. A., Villanueva-Amadoz, U., Pons, D., Diez, J. B. & Ferrer, J. 2016. First records of the angiosperm genus Sapindopsis Fontaine (Platanaceae) in western Eurasia from middle to latest Albian deposits of Spain. Review of Palaeobotany and Palynology, 230, 10–21.
   Web of Science ®Google Scholar
• Smith, S. Y. 2013. The fossil record of noncommelinid monocots. Pp. 29–59 in P. Wilkin & S. J. Mayo (eds) Early Events in Monocot Evolution. Cambridge University Press, Cambridge, UK.
   Google Scholar
• Stebbins, G. L. & Khush, G. S. 1961. Variation in the organization of the stomatal complex in the leaf epidermis of monocotyledons and its bearing on their phylogeny. American Journal of Botany, 48, 51–59.
   Web of Science ®Google Scholar
• Stockey, R. A. 2006. The fossil record of basal monocots. Aliso, 22, 91–106.
   Google Scholar
• Stockey, R. A., Rothwell, G. W. & Johnson, K. R. 2007. Cobbania corrugata gen. et comb. nov. (Araceae): a floating aquatic monocot from the Upper Cretaceous of western North America. American Journal of Botany, 94, 609–624.
   PubMed Web of Science ®Google Scholar
• Stockey, R. A., Rothwell, G. W. & Johnson, K. R. 2016. Evaluating relationships among floating aquatic monocots: a new species of Cobbania (Araceae) from the upper Maastrichtian of South Dakota. International Journal of Plant Sciences, 177, 706–725.
   Web of Science ®Google Scholar
• Swofford, D. L. 1990. PAUP: Phylogenetic Analysis Using Parsimony. Version 3.0. Illinois Natural History Survey, Champaign, Illinois.
   Google Scholar
• Teixeira, C. 1948. Flora Mesozóica Portuguesa. Serviços Geológicos de Portugal, Lisbon, 118 pp.
   Google Scholar
• Teixeira, C. 1950. Flora Mesozóica Portuguesa. II Parte. Serviços Geológicos de Portugal, Lisbon, 33 pp.
   Google Scholar
• Tomlinson, P. B. 1974. Development of the stomatal complex as a taxonomic character in the monocotyledons. Taxon, 23, 109–128.
   Google Scholar
• Upchurch, G. R. 1984. Cuticle evolution in Early Cretaceous angiosperms from the Potomac Group of Virginia and Maryland. Annals of the Missouri Botanical Garden, 71, 522–550.
   Web of Science ®Google Scholar
• Upchurch, G. R. 1995. Dispersed angiosperm cuticles: their history, preparation, and application to the rise of angiosperms in Cretaceous and Paleocene coals, southern western interior of North America. International Journal of Coal Geology, 28, 161–227.
   Web of Science ®Google Scholar
• Villanueva-Amadoz, U., Sender, L. M., Diez, J. B., Ferrer, J. & Pons, D. 2011. Palynological studies of the Boundary Marls unit (Albian–Cenomanian) from northeastern Spain. Paleophytogeographical implications. Geodiversitas, 33, 137–176.
   Web of Science ®Google Scholar
• Walker, J. W. & Walker, A. G. 1986. Ultrastructure of Early Cretaceous angiosperm pollen and its evolutionary implications. Pp. 203–217 in S. Blackmore & I. K. Ferguson (eds) Pollen and Spores: Form and Function. Academic Press, London.
   Google Scholar
• Zomlefer, W. B. 1997. The genera of Tofieldiaceae in the southeastern United States. Harvard Papers in Botany, 2, 179–194.
   Google Scholar