Corrections Proc. Nati. Acad. Sci. USA 89 (1992) 12207 Eveduton. In the article "Oldest fossil-flowers of hamael- ber 1, 1992, of Proc. Nati. Acad. Sci. USA (89, 8986-89), idaceous affinity, from the Late Cretaceous of New Jersey" the reproduction of Fig. 1 was not satisfactory (due to a by William L. Crepet, Kevin C. Nixon, Else Marie Friis, and printer's error, a splotch appeared between E and H). The John V. Freudenstein, which appeared in number 19, Octo- figure and its legend are reproduced below. IUItI j~i~I;I S- 0 F I ,...A .-- :.i; :1 :4 FIG. 1. Scanning electron micrographs of fossil inflorescences, flowers and organs. (A) Capitate staminate inflorescence showing florets, sepal cap lobes (sc). Each flower with four triangular stamen connectives (c), visible within sepal cup. (x23.) (B) One floret from a staminate inflorescence showing slightly separated anther connectives (c) opposite sepal cup lobes (sc). (x60.) (C) A lateral view of a partially broken staminal tube (st), within a sepal cup (sc), illustrating the thin-walled nature ofthe staminal tube, its hollow interior, and apical staminodes with adaxially bulbous extremities (bs). (x70.) (D) Floret with anthers removed, showing sepal cup and four sagittate staminode heads. (x55.) (E) Floret with two whole stamens removed revealing the incurved, contiguous staminodes (s) and one anther (a) sheared off illustrating cellular preservation. (x70.) (F) Closer view ofdistal staminode showing sagittate head (arrow), similar to shape offertile stamens. (x 140.) (G) Stamen removed from a floret showing the sagittate distal connective and thecae with slightly open valves. (x60.) (H) A single in situ pollen grain. (x4000.) (I) Pistillate inflorescence showing the somewhat abraded carpels and sepal lobes. (x34.) (J) Distal adaxial stamen connective epidermis showing three anomocytic stomata-one with broken guard cell walls. (x560.) (K) Close-up of a staminate floret with stamens removed to show the partially abraded sagittate heads of two staminodes (sh) and the broken stamen filament (sf) that appears to be interior to the two staminodal stalks. Note the broken sepal cup (arrow) for perspective. (x40.) (L) One tangentially sheared pistillate floret showing the bicarpellate syncarpous ovary inside of a sepal cup. (x105.) Downloaded by guest on October 1, 2021 Proc. Nati. Acad. Sci. USA Vol. 89, pp. 8986-8989, October 1992 Evolution Oldest fossil flowers of hamamelidaceous affinity, from the Late Cretaceous of New Jersey (Anglospermae/Hamaeiddae/pofna on/phylogeny) WILLIAM L. CREPET*, KEVIN C. NIXON*, ELSE MARIE FRlISt, AND JOHN V. FREUDENSTEIN* *L. H. Bailey Hortorium, Cornell University, Ithaca, NY 14853; and tNaturhistoriska Riksmuseet, Department of Palaeobotany, S-104 05 Stockholm, Sweden Communicated by Peter H. Raven, June 23, 1992 (receivedfor review November 4, 1991) ABSTRACT Exceptionally well-preserved staminate inflo- cellular and epidermal features. It has been suggested that rescences, pistillate inflorescences, and detached stamens with this type of preservation is the result of rapid charcoalifica- important phylogenetic and paleoecological implications have tion during ancient flash forest fires (4). Fossils are isolated been discovered from the Turonian (ca. 88.5-90.4 million from the matrix by dissolving the matrix in water and sieving, years B.P.) Raritan Formation of New Jersey. The fossils have followed by tedious sorting oftiny fragments ofcharcoalified a combination of floral and pollen characters found in various material. In addition to a large and growing number of other genera ofmodern entomophilous and anemophilous Hamamel- angiosperm taxa, a series of fossil staminate inflorescences, idaceae and anemophilous Platanus (Platanaceae). The floral pistillate inflorescences, and detached stamens of apparent characters of the fossils, induding a sepal cup, stamil tube, hamamelidaceous/platanoid affinity have been discovered and apparently nectariferous staminodes, indicate that this by these methods. These fossils were all removed from a taxon was probably insect pollinated. The juxtaposition of relatively small sample (ca. 15 kg of matrix). One striking character complexes in an extinct taxon from disparate modern aspect of these fossil flowers is the extremely small size (see taxa provides an interesting phylogenetic perspective on the below), a feature of virtually all of the fossil flowers isolated origins of Iamamelidaceae and is a striking example of a fossil from these sites to date. that is a mosaic of familial level characters relative to modern Fossil staminate heads are ca. 1-2 mm in diameter, with taxa. Of even broader interest, however, is the occurrence of about 15 sessile, tightly packed florets (Fig. 1A). Individual stMinodal nectaries that have structural characters interme- florets are between 0.5 and 0.75 mm in width. Staminate diate between the fossil's functional stamens and modern florets have a sepal cup that is distally four-lobed (Fig. 1 B and hamamelidaceous petals. This transitional staminode morphol- D). In young inflorescences, the sepal lobes are slightly ogy in the context of the other fossil characters suggests a imbricate. Each flower has four functional stamens that are staminodal origin of petals in the hamamelid-rosid lineage. free from the calyx and inserted opposite the calyx lobes (Fig. This hypothesis is supported by the apparent staminode posi- 1B). The most striking features of the stamens are the tion within the fossil flowers where petals are found in modern massive incurved connectives (Fig. 1B). These appear trian- genera. The character complex ofmorphologically transitional gular in surface view, have a nonpapillar, smooth surface staminodes, a staminal tube, and sepal cup can be viewed as with anomocytic stomata (Fig. 1J), and have small auricular prehypanthial, lacking only fusion of the staminal tube to the extensions resulting in a sagittate outline (Fig. 1G). Stamens sepal cup. The appearance of the character complex embodied have very short filaments with almost sessile anthers that in these flowers during the late mid-Cretaceous may signal the have two locules at maturity (Fig. 1G). Each anther locule of has a single elongate slit that is bifurcate at one or both ends, early stages the relationship between specialized pollinators, suggesting that anther dehiscence was valvate. Four stami- such as bees, and the h a elid-rosid-asterid lineage of nodes are present in a single whorl alternate with the fertile angiosperms, arguably one of the most important events in stamens and inside the calyx (Fig. 1 E, F, and K). These angiosperm radiation. staminodes are strongly incurved, and their distal heads actually touch or overlap slightly in the central portion of the One of the dilemmas facing paleobotanists is the rarity of flower (Fig. 1 E and K). Below the anthers, the filaments of fossil taxa that are phylogenetically informative-i.e., that both staminodes and stamens are united into a hollow, are mosaics ofcharacters found in separate modern taxa. The cylindrical/hourglass-shaped staminal tube (Fig. 1C). The fossils described below, from the Turonian (88.5-90.4 million staminal filaments appear to originate inside of the whorl of years B.P.; ref. 1) Raritan Formation ofNew Jersey (2, 3), are staminodes (Fig. 1K). Although the traces that lead to the a notable exception. These fossils have a character mosaic of staminodes also appear to be inserted slightly outside of the the modern hamamelidid families Platanaceae and Hamamel- stamen traces in specimens where the staminal tube is idaceae and are therefore of considerable phylogenetic in- broken, this filament tube is extremely thin and it is difficult terest. They also provide evidence about the origin of petals to be certain of the relative positions of the whorls that form in a major lineage of flowering plants, the Hamamelididae- it, presumably by congenital fusion. Each staminode has a Rosidae-Asteridae lineage, which is now associated with stalk inserted at the rim of the tube and a sagittate head specialized insect pollinators. The exceptional quality of shaped like an anther connective (Fig. 1 C, E, F, and K). preservation makes it possible to detect minute, but highly Abaxial surface cells of the expanded staminode head are significant, structural features that typically would not be larger than those ofthe stalk (Fig. iF). Adaxially, staminodes found even in very well-preserved fossils. are expanded into hemispherical protuberances composed of The majority of fossils at the Raritan site are charcoalified large thin-walled cells that project downward into the stam- and three-dimensional (not noticeably compressed), with inal tube (Fig. 1C). Even at high magnification with scanning moderate to extraordinary preservation of details such as electron microscopy, there is no evidence of gynoecia or of pistillodes at the bases of the staminal tubes in any of the The publication costs of this article were defrayed in part by page charge fossils examined; therefore we interpret these as completely payment. This article must therefore be hereby marked "advertisement" unisexual inflorescences. Staminodes are routinely observed in accordance with 18 U.S.C. §1734 solely to indicate this fact. in fossil flowers that appear to have been fully mature at the 8986 Evolution: Crepet et al. Proc. Natl. Acad. Sci. USA 89 (1992) 8987 FIG. 1. Scanning electron micrographs of fossil inflorescences, flowers, and organs. (A) Capitate staminate inflorescence showing