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1 Department of Biological Sciences, The George Washington University, 2023 G Street NW, Washington, DC 20052 USA; and Department of Geological Sciences, P.O. Box 750395, Southern Methodist University, Dallas, Texas 75275-0395 USA
Received for publication June 15, 1999. Accepted for publication January 20, 2000.
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSSYSTEMATICSDISCUSSIONLITERATURE CITED |
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Key Words: Caesalpinioideae • Eocene • Leguminosae • Mimosoideae • paleobotany • Paleogene • Tanzania
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSSYSTEMATICSDISCUSSIONLITERATURE CITED |
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; Harrison et al., 1998
). Fossil leaves from Mahenge present a rare opportunity to document the early history of the Leguminosae in tropical Africa and provide the first terrestrial proxy from which paleoclimate reconstructions will be made for the African Paleogene. This paper focuses on the systematic placement of fossil legumes collected during initial investigations at the site.
The fossiliferous lacustrine sediments at Mahenge are directly associated with an underlying kimberlite deposit. Kimberlites, best known as the source rock for diamonds, are heavy-mineral, igneous intrusions that are common in southern and East Africa (Mannard, 1962
; Edwards and Howkins, 1966
; Rayner and McKay, 1986
; Smith, 1986
). However, only a few kimberlite-associated fossil localities have been collected and studied in detail. These include the Late Cretaceous age Orapa site in Botswana and Stompoor site in South Africa (Rayner and McKay, 1986
; Smith, 1986
; Rayner, 1987
; Bamford, 1989
; Rayner et al., 1991
). Thus, kimberlite-associated lacustrine sediments remain an underutilized resource for paleontological and paleoenvironmental investigations.
The Mahenge site was originally reported by Mannard (1962)
, but only recently has the site been the subject of concentrated paleontological excavation and study (Harrison, 1997
; Harrison et al., 1998
). Recent collections of fossil plants from Mahenge consist of at least 20 angiosperm leaf morphologies (presumed to represent 20 species) among 70 specimens from the laminated mudstone deposits. A relatively diverse component of this assemblage is the family Leguminosae. Described here are five species of legumes represented by a total of seven specimens. At least three of the legume leaf types are referable to the Caesalpinioideae and one to the Mimosoideae.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSSYSTEMATICSDISCUSSIONLITERATURE CITED |
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; Rayner and McKay, 1986
; Smith, 1986
). Mannard (1962)
documented the geologic setting of 54 kimberlites in the Singida, Tanzania, area while exploring their potential for diamond production. Many of the Singida kimberlites formed crater-lakes as a consequence of their eruption at the Earth's surface (Mannard, 1962
). Exploratory excavation of deposits at the Mahenge site (4°47'38'' S; 34°15'28'' E), 63 km west of the town of Singida (Fig. 1), yielded fossil plants and fish from an enclosed paleolake estimated to have been 
400 m in diameter (Greenwood, 1960
; Mannard, 1962
; Greenwood and Patterson, 1967
). The Wembere-Manonga Palaeontological Expedition greatly increased the collection of fish, plants, amphibians, and insects from expanded excavation at Mannard's locality near the center of the paleolake (Harrison et al., 1998
). The lacustrine deposits consist of 1.5 m of laminated mudstone wherein plant fossils are found as compressions and impressions occurring along bedding planes. Many specimens have fine venation details preserved, but cuticle is poorly preserved or lacking. Evidence for the presence of anoxic lake bottom conditions (at least periodically) includes the preservation of soft parts with the skeletal remains of vertebrates and an absence of bioturbation (Harrison, 1997
). Differential preservation of leaves would be minimal under these conditions.
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). Thus, the maximum age of the Mahenge fossils is early middle Eocene (timescale of Berggren et al., 1995
). Lake deposition most likely began soon after formation of the crater associated with the eruption event and probably occurred during the time period covered by the standard error of the date.
Fossil specimens that were partially obscured by rock matrix were uncovered using a dental pick or an air scribe. Care was taken in searching for and uncovering the petiole and rachis of each specimen to document pulvinus position and the structure and number of leaflets or leaflet scars. Cuticle preparations were unsuccessful because cuticle is poorly preserved. Specimens were photographed using low-angle lighting to reveal venation details. Extant material for comparison was obtained from MO, F, US, and K. Clearings of leaflets to reveal venation details were prepared according to the methods in Herendeen and Dilcher (1990)
.
Fossils will be housed permanently at the National Museums of Tanzania, Dar Es Salaam, but will retain the field numbers cited here.
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SYSTEMATICS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSSYSTEMATICSDISCUSSIONLITERATURE CITED |
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Subfamily
Caesalpinioideae.
Tribe
Amherstieae.
Aphanocalyx singidaensis
Herendeen and Jacobs, sp. nov.
Holotype
WM277/96. National Museums of Tanzania, Dar es Salaam.
Paratypes
WM288/96, WM435/96.
Figures
Figs. 2–6.
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3.5 mm long, 2 mm wide, with prominent transverse wrinkles or striations. Distal pulvinus well developed, 4 mm long, 2.5 mm wide. No rachis extension beyond attachment of terminal leaflets. Leaflets incompletely preserved, sessile, lacking well-differentiated petiolule, markedly asymmetrical, at least 6.0 cm long (all three specimens lacking apex), maximum width 19–28 mm near the center of the leaflet. Leaflet base asymmetrical, acute to obtuse, apex apparently acute but whether entire or emarginate is unknown. Leaflet pulvinus well developed. Leaflet venation consists of a single eccentric primary vein, with the leaflet lamina on the proximal (outer) side of the primary vein much wider (15–23 mm) than the lamina on the distal (inner) side of the primary vein (2–4 mm). Inner lamina widest near the center of the leaflet, tapering toward the base and apex. Venation of the inner and outer lamina dissimilar. Inner lamina venation composed of approximately ten eucamptodromous secondary veins, generally with 1–2 intersecondaries between secondary veins. Tertiary veins weakly percurrent and sinuous to reticulate proximally, strongly percurrent, straight distally. Quaternary and quinternary veins more or less orthogonal reticulate. Areole venation not preserved. Outer lamina venation essentially basal acrodromous with 4–5 veins arising from the leaflet pulvinus. Basal acrodromous veins form convergent arches toward the leaflet apex. The vein closest (adjacent) to the primary vein is the widest of the basal acrodromous veins and extends for most of the length of the leaflet. The outermost vein is the weakest of the acrodromous veins, and it is distinguishable for less than one-fifth of the length of the leaflet before it anastomoses with the finer venation. Four to six eucamptodromous secondary veins arise from the primary vein; tertiary and higher order venation is essentially random reticulate. Cuticle not preserved.
Comments and discussion
This leaf type (Figs. 2–6) is clearly bifoliolate (composed of one pair of two leaflets). One specimen (WM288/96) has both the lower pulvinus, which occurs at the base of the petiole, and the upper pulvinus at the attachment of the single pair of leaflets (Fig. 6). The inner lamina on one specimen (WM277/96) is not continuous to the base (Figs. 2, 3). This portion of the lamina appears to be damaged and is thus an artifact of preservation. The other two specimens clearly show the inner lamina tapering to the base of the leaflet.
Systematic relationships
This fossil leaf type is similar to leaves found in several genera of the caesalpinioid tribes Detarieae and Amherstieae (Figs. 7–12, Table 1; Cowan and Polhill, 1981
). Of the 80 genera in these tribes the fossils are most comparable in structure and venation detail to leaves of the genus Aphanocalyx, especially A. cynometroides (Fig. 7). The number of basal acrodromous veins, relative length of the longest basal acrodromous vein, position of the primary vein (i.e., relative width of outer lamina vs. inner lamina), and secondary venation pattern are all features that are most similar to A. cynometroides (Table 1). Two other species of Aphanocalyx (A. djumaensis [Fig. 8] and A. richardsiae [Fig. 9]) have leaves that are very similar to those of the fossil species and A. cynometroides (Table 1), but they differ in the position of the primary vein along the inner leaflet margin (i.e., leaflet lamina distal to the primary vein is lacking; Figs. 8, 9).
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and now consists of 14 extant species concentrated in tropical western Africa, and extending to Zambia and western Tanzania (Wieringa, 1999
). Prior to Wieringa's revision Aphanocalyx was regarded as most closely related to Monopetalanthus, and these genera were often grouped with other genera such as Tetraberlinia, Michelsonia, Brachystegia, and others (Brenan, 1967
; Cowan and Polhill, 1981
). Wieringa (1999)
revised Aphanocalyx, Monopetalanthus, Tetraberlinia, and Michelsonia and transferred eight species of Monopetalanthus to Aphanocalyx, including M. richardsiae, and M. leonardii, which he combined in synonymy as M. richardsiae. Six other species of Monopetalanthus were transferred to a new genus, Bikinia, and one other species of Monopetalanthus was transferred to Tetraberlinia. All of the extant species that are most comparable to the fossil are now included in Aphanocalyx.
Tribe
Detarieae or Amherstieae.
Cf. Cynometra.
Specimen
WM151/96.
Figures
Figs. 13–15.
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1 mm long, 0.9 mm wide, and a well-developed upper pulvinus, 1.5 mm long, 1.0 mm wide. Upper and lower pulvini have well-developed transverse wrinkles or striations. No rachis extension beyond attachment of the terminal leaflets. Leaflets incompletely preserved, sessile, lacking well-differentiated petiolule, markedly asymmetrical, at least 3.0 cm long (apex not preserved), maximum width 1.2 cm near the center of the leaflet. Leaflet base acute, asymmetrical. Leaflet pulvinus well developed. Leaflet primary vein eccentric, leaflet lamina on proximal (outer) side of primary vein wider (7–8 mm) than that on the inner side of the primary vein (4.0–4.5 mm). Venation of the inner lamina poorly preserved, secondary veins eucamptodromous, number of secondaries unknown; finer venation poorly preserved, reticulate. Outer lamina venation poorly preserved, with 1–2 basal acrodromous veins arising from the leaflet pulvinus and arching toward the leaflet apex. The strongest basal acrodromous vein is distinguishable for one-third of the length of the leaflet (anastomoses and is indistinguishable beyond the basal third of the leaflet). Secondary veins at least eight, relatively closely spaced, eucamptodromous, at least in the lower part of the leaflet. Tertiary and higher order venation poorly preserved, essentially random reticulate. Cuticle not preserved.
Comments and discussion
This fossil leaf type (Figs. 13–15) is similar to the previous type in being bifoliolate. However, this taxon differs from the previous one in the number and extent of basal acrodromous veins, position of the primary vein, and details of secondary venation pattern. They also differ in size, but this may not be especially significant because leaf and leaflet size can vary significantly from shoot base to apex within a single plant.
Systematic relationships
This fossil leaf type is most similar to leaves of several genera in the caesalpinioid tribes Detarieae and Amherstieae (Table 1; Cowan and Polhill, 1981
). Specifically, the fossil is most comparable to the genus Cynometra (Fig. 10), but the single specimen available with incomplete leaflets and little venation detail precludes detailed comparisons until additional material is available.
Subfamily
Caesalpinioideae.
Genus
Unknown.
Specimens
WM515/96.
Figures
Figs. 16, 17.
Description
Leaflet asymmetrical, sessile, lacking well-differentiated petiolule, pulvinus well developed with transverse wrinkles or striations; apex not preserved; base obtuse, asymmetrical. Length at least 25 mm, maximum width 14 mm near center of the leaflet. Primary vein eccentric, leaflet lamina on presumed proximal (inner) side of primary vein much wider (9 mm) than the lamina on the presumed distal (outer) side of the primary vein (5 mm). Venation of the narrow side of leaflet eucamptodromous, with at least five secondary veins with 1–2 intersecondary veins between adjacent secondary veins. Tertiary veins random to orthogonal reticulate. Finer venation reticulate, poorly preserved. Venation of the wider side of leaflet with two basal acrodromous veins arising from the leaflet pulvinus and arching toward the leaflet apex. The strongest basal acrodromous vein is distinguishable for the entire portion of the leaflet that is preserved. The second basal acrodromous vein is distinguishable for approximately one-third of the preserved portion of the leaflet. Secondary veins at least four, essentially eucamptodromous, anastomosing with tertiary and inner acrodromous vein. Tertiary veins predominantly orthogonal reticulate. Finer venation reticulate, poorly preserved. Cuticle not preserved.
Comments and discussion
This taxon is represented by a single incomplete leaflet (Figs. 16, 17). The morphology of the complete leaf is unknown.
Systematic relationships
This specimen has a morphology that is characteristic of Caesalpinioideae, especially some Detarieae and Amherstieae. Although venation is well preserved, there are insufficient morphological details present to assess relationships further. Most useful would be information about leaflet apex structure and leaflet arrangement.
Subfamily
Unknown.
Specimen
WM003/96.
Figures
Figs. 18, 19.
Description
Leaf pinnately compound, leaflets opposite, at least 20 pairs. Specimen incomplete, 46 mm long, base and apex not preserved. Leaflets oblong, 5–10 mm long, 1.5–2.0 mm wide; apex acute, base poorly preserved, asymmetrical, sessile; petiolule apparently absent. Venation not preserved.
Comments and discussion
It is not possible to determine from the single incomplete specimen whether the leaf is pinnate vs. bipinnate, or paripinnate vs. imparipinnate. The preservation is poor, and venation is not present.
Systematic relationships
The gross morphology of the specimen is consistent with Leguminosae, especially Caesalpinioideae or Mimosoideae, but there are insufficient details to assess relationships.
Subfamily
Mimosoideae.
Tribe
Acacieae.
Acacia mahengense
Herendeen et Jacobs, sp. nov.
Holotype
WM285/96. National Museums of Tanzania, Dar es Salaam.
Figures
Figs. 20–24.
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1 mm wide at base, basal pulvinus well developed. Pinnae bear at least 40 pairs of small leaflets. Leaflets 4–5 mm long, 1 mm wide; petiolule well developed, very short, 0.5 mm long, 0.3 mm wide; pulvinus well developed with transverse wrinkles. Lamina base asymmetrical, proximal corner ±90°, angular, distal corner rounded; lamina apex rounded with mucronate tip. Lamina slightly broader on the proximal side than on the distal side of the primary vein. Secondary venation and higher order veins not preserved. Cuticle not preserved.
Comments and discussion
A cavity on the rachis immediately below one pair of pinnae scars probably represents an artifact of preservation rather than a foliar nectary. The outline of the cavity is somewhat irregular. There is no other evidence of prickles, spines, or foliar nectaries on the leaf rachis.
Systematic relationships
This fossil bipinnate leaf is clearly referable to the subfamily Mimosoideae. The genera Acacia, Adenanthera, Albizia, Dichrostachys, Endata, Mimosa, and Pithecellobium are most relevant for comparison based on similarities in gross morphology. Of these genera, the fossil leaf is identical to leaves of many species of the genus Acacia, which consists of 1000 species, of which 70 occur in Tanzania today (Brenan, 1959
; Allen and Allen, 1981
; Vassal, 1981
). Characters supporting the assignment to Acacia include: relatively few pairs of opposite pinnae, absence of prickles or paired spines on the primary rachis, pinnae relatively long with numerous, opposite, small leaflets, petiolule well developed but short, leaflet primary vein near center of leaflet, leaflet apex symmetrical, leaflet base nearly symmetrical, no evidence of basal acrodromous veins in proximal lamina.
The taxonomy of Acacia is complicated, and reproductive material is required to evaluate relationships within the genus. This fossil represents the earliest unequivocal record for Acacia in Africa and is the only record from the Paleogene. Fossil flowers and leaf pinnae of Acacia were described based on material in amber from the Dominican Republic (Dilcher, Herendeen, and Hueber, 1992
). The Dominican amber is thought to be of late Early Miocene through early Middle Miocene age (15–20 million years before present) (Iturralde-Vincent and MacPhee, 1996
).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSSYSTEMATICSDISCUSSIONLITERATURE CITED |
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). Nevertheless, they firmly establish the presence of caesalpinioid and mimosoid legumes in Africa during that time. Salard-Cheboldaeff and Dejax (1991)
report two kinds of caesalpinioid pollen in West Africa beginning in the earliest Eocene. Fossil pollen of Mimosoideae, including several types of mimosoid polyads, have been described from Eocene to Miocene sediments from Cameroon and Egypt (Guinet and Salard-Cheboldaeff, 1975
; Salard-Cheboldaeff, 1978
; Guinet et al., 1987
).
African Paleogene fossil wood localities are more numerous, but are poorly dated, and specimens are often identified to the family level using form taxa such as Leguminoxylon. However, Dupéron-Laudoueneix and Dupéron (1995)
report the occurrence of Caesalpinioxylon tiemassaense Koeniguer (Eocene, Senegal), Nicolia aegyptiaca Unger (terminal Cretaceous-Eocene, Ethiopia), Tiemassaxylon (Caesalpinioxylon?) eocenicum Koeniguer (lower Eocene, Senegal), and Pahudioxylon menchikoffii (Boreau) Muller-Stoll and Madel (Eocene, Algeria), all of which are known to occur in Eocene deposits and have affinities with extant Caesalpinioideae. Fossil caesalpinioid wood with well-documented vestured pits has been described by Crawley (1988)
from the middle to upper Paleocene of Mali. Lower Oligocene mimosoid wood from Egypt is reported as Acaciaoxylon antiquum Schenk (=Dalbergioxylon dicorynioides Muller-Stoll and Mädel; Gros, 1992
) and Acacioxylon vegae Schenk (Gros, 1992
; Dupéron-Laudoueneix and Dupéron, 1995
). The Oligocene Jebel Qatrani Formation contains probable caesalpinioid leaves in a paleoflora interpreted to have come from a local riverine or near coastal forest (Bown et al., 1982
). In a summary of the Tertiary paleobotanical record in Africa north of the Equator, Boureau et al. (1983)
list numerous fossil wood taxa, including caesalpinioid, mimosoid, and papilionoid legumes from Paleogene and Neogene sediments.
At Mahenge, legumes are a significant component of the flora; they comprise 25% of species and 10% of specimens in this small assemblage. From the diversity of legumes at Mahenge and among other sites, it is clear that legumes (especially caesalpinioid legumes) were well represented in the Paleogene of Africa. Further research on Mahenge fossil plants is expected to yield a more detailed understanding of systematic and biogeographic relationships for the fossil legumes found there.
The vegetation at Mahenge was woodland (open or closed), rather than forest, and the climate was warm (or hot) and seasonally dry, on the basis of qualitative assessment of margin and size characters recorded for the 20 woody dicot leaf morphologies (Harrison et al., 1998
; Harrison et al., 2000
[quantitative climate reconstruction will be made using enlarged collections from Mahenge]). This interpretation is supported by the presence of Acacia, which today grows only in relatively dry woodland or more open environments. Although it could reflect local conditions, this reconstruction is consistent with early to middle Eocene paleoenvironmental interpretations for West Africa and Egypt based on limited palynological data. The continual presence of Monoporites annulatus (presumed to be grass pollen) in Paleocene and Eocene core samples from coastal Cameroon is taken to indicate relatively more aridity than in the Late Eocene and Oligocene, when angiosperm richness is higher and M. annulatus disappears (Salard-Cheboldaeff, 1981
; Adegoke et al., 1978
). Monoporites annulatus is reported as abundant in early Eocene core samples from Egypt (Kedves, 1971
) and also interpreted as an indication of relative aridity.
West African pollen studies generally document increasing diversity of angiosperm dicots from the Late Cretaceous through the Oligocene (Van Hoeken-Klinkenberg, 1966
; Salard-Cheboldaeff, 1979, 1981
), and Salard-Cheboldaeff (1981)
interprets this record as representing the initial development of West and Central African wet lowland forest vegetation. In contrast, an earlier overview by Axelrod and Raven (1978)
depicts lowland rain forest for paleolatitudes northward of 15° S during the Paleocene and Eocene (the paleolatitude at Mahenge is 15° S). The intriguing notion of rain forest development during and after the Late Eocene and the alternate view that rain forest vegetation would have been established across Africa during the Paleocene and Eocene require resolution from additional paleobotanical data and better chronological control. Expanded knowledge of early Tertiary paleobotany in Africa may come from further investigations at Mahenge and other kimberlite-associated Paleogene crater lake deposits. When African Paleogene floristics, systematics, and paleoecology are known in more detail they can be understood in the broader contexts of the extant African flora and the better known Northern Hemisphere paleobotanical record.
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FOOTNOTES |
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LITERATURE CITED |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSSYSTEMATICSDISCUSSIONLITERATURE CITED |
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Allen, O. N., and E. K. Allen. 1981 The Leguminosae. A source book of characteristics, uses, and nodulation. University of Wisconsin Press, Madison, Wisconsin, USA
Axelrod, D. I., and P. H. Raven. 1978 Late Cretaceous and Tertiary vegetation history of Africa. In M. J. A. Werger [ed.], Biogeography and ecology of southern Africa, 77–130. W. Junk, The Hague, The Netherlands
Bamford, M. K. 1989 The angiosperm palaeoflora from the Orapa Pipe, Botswana. Ph.D. Dissertation, University of the Witwatersrand, Johannesburg, South Africa
Berggren, W. A., D. V. Kent, C. C. Swisher, and M.-P. Aubry. 1995 A revised Cenozoic geochronology and chronostratigraphy. In W. A. Berggren, D. V. Kent, M.-P. Aubry, and J. Hardenbol [eds.], Geochronology, time scales and global stratigraphic correlation, SEPM Special Publication, Number 54, 129–212. SEPM (Society for Sedimentary Geology), Tulsa, Oklahoma, USA
Boureau, E., M. Cheboldaeff-Salard, J.-C. Koeniguer, and P. Louvet. 1983 Evolution des flores et de la végétation Tertiaires en Afrque, au nord de l'Equateur. Bothalia 14: 355–367
Bown, T. M., M. J. Kraus, S. L. Wing, J. G. Fleagle, B. H. Tiffney, E. L. Simons, and C. F. Vondra. 1982 The Fayum primate forest revisited. Journal of Human Evolution 11: 603–632
Brenan, J. P. M. 1959 Leguminosae subfamily Mimosoideae. In C. E. Hubbard and E. Milne-Redhead [eds.], Flora of tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, UK
———. 1967 Leguminosae subfamily Caesalpinioideae. In E. Milne-Redhead and R. M. Polhill [eds.], Flora of tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, UK
Cowan, R. S., and R. M. Polhill. 1981 Amherstieae. In R. M. Polhill and P. H. Raven [eds.], Advances in legume systematics, part 1, 135–142. Royal Botanic Gardens, Kew, Richmond, Surrey, UK
Crawley, M. 1988 Palaeocene wood from the Republic of Mali. Bulletin of the British Museum of Natural History (Geology) 44: 3–14
Dilcher, D. L., P. S. Herendeen, and F. Hueber. 1992 Fossil Acacia flowers with attached anther glands from Dominican Republic amber. In P. S. Herendeen and D. L. Dilcher [eds.], Advances in legume systematics, part 4. The fossil record, 33–42. Royal Botanic Gardens, Kew, Richmond, Surrey, UK
Dupéron-Laudoueneix, M., and J. Dupéron. 1995 Inventory of Mesozoic and Cenozoic woods from equatorial and north equatorial Africa. Review of Palaeobotany and Palynology 84: 439–480[CrossRef][ISI]
Edwards, C. B., and J. B. Howkins. 1966 Kimberlites in Tanganyika with special reference to the Mwadui occurrence. Economic Geology 61: 537–554
Greenwood, P. H. 1960 Fossil denticipitid fishes from East Africa. Bulletin of the British Museum of Natural History. Geology 5: 1–11
———, and C. Patterson. 1967 A fossil osteoglossoid fish from Tanzania (E. Africa). Journal of the Linnean Society (Zoology) 47: 211–223
Gros, J. P. 1992 A synopsis of the fossil record of mimosoid legume wood. In P. S. Herendeen and D. L. Dilcher [eds.], Advances in legume systematics, part 4, The fossil record, 69–83. Royal Botanic Gardens, Kew, Richmond, Surrey, UK
Guinet, Ph., and M. Salard-Cheboldaeff. 1975 Grains de pollen du Tertiaire du Cameroun pouvant entre rapportès aux Mimosacèes. Boissiera 24: 21–28
———, N. El Sabrouty, H. Soliman, and A. M. Omran. 1987 Etude des characteres du pollen des Leguminoseuses-Mimosoideae des sèdiments Tertiaires de nord-ouest de l'Egypte. Memoires et Travaux, École Pratique des Hautes Études de l'Institut de Montpellier 17: 159–171
Harrison, T. 1997 Wembere-Manonga Palaeontological Expedition: Field Report, 1996. Unpublished Report to Director of Antiquities, Dar es Salaam, Tanzania
———, C. P. Msuya, A. Murray, B. F. Jacobs, A. M. Báez, K. R. Ludwig, and R. Mundil. 2000 Paleontological investigations at the Eocene locality of Mahenge in north-central Tanzania, East Africa. In G. F. Gunnell [ed.], Eocene vertebrates: unusual occurrences and rarely sampled habitats. Topics in Geobiology Series. Plenum, New York, New York, USA
———, A. Murray, C. P. Msuya, B. F. Jacobs, and A. M. Baez. 1998 Mahenge: an Early Eocene lagerstätte in Tanzania, East Africa. Journal of Vertebrate Paleontology 18: 49A
Herendeen, P. S., W. L. Crepet, and D. L. Dilcher. 1992 The fossil history of the Leguminosae: phylogenetic and biogeographic implications. In P. S. Herendeen and D. L. Dilcher [eds.], Advances in legume systematics, part 4, The fossil record, 303–316. Royal Botanic Gardens, Kew, Richmond, Surrey, UK
———, and D. L. Dilcher. 1990 Reproductive and vegetative evidence for the occurrence of Crudia (Leguminosae, Caesalpinioideae) in the Eocene of southeastern North America. Botanical Gazette 151: 402–413
Iturralde-Vincent, M. A., and R. D. E. MacPhee. 1996 Age and paleogeographical origin of Dominican Amber. Science 273: 1850–1852
Kedves, M. 1971 Presence de types sporomorphes importants dans les sediments pre-quaternaires Egyptiens. Acta botanica Academiae Scientiarum Hungaricae 17: 371–378
Mannard, G. W. 1962 The geology of the Singida kimberlite pipes, Tanganyika. Ph.D. Dissertation, McGill University, Montreal, Canada
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———, and I. J. McKay. 1986 The treasure chest of the Orapa diamon mine. Botswana Notes and Records 18: 55–61
———, S. B. Waters, I. J. McKay, and P. N. Dobbs. 1991 The mid-Cretaceous palaeoenvironment of central southern Africa (Orapa, Botswana). Palaeogeography, Palaeoclimatology, Palaeoecology 88: 147–156[CrossRef]
Salard-Cheboldaeff, M. 1978 Sur la palynoflore Maestrichtienne et Tertiaire du Bassin sèdimentaire Littoral du Cameroun. Pollen et Spores 20: 215–260
———. 1979 Palynologie Maestrichtienne et Tertiaire du Cameroun. Etude qualitative et répartition verticale des principales espècies. Review of Palaeobotany and Palynology 28: 365–388
———. 1981 Palynologie Maestrichtienne et Tertiaire du Cameroun. Résultats botaniques. Review of Palaeobotany and Palynology 32: 401–439[CrossRef]
———, and J. Dejax. 1991 Evidence of Cretaceous to Recent West African intertropical vegetation from continental sediment spore-pollen analysis. Journal of African Earth Sciences 12: 353–361[CrossRef][ISI]
Smith, R. M. H. 1986 Sedimentation and palaeoenvironments of Late Cretaeous crater-lake deposits in Bushmanland, South Africa. Sedimentology 33: 369–386[CrossRef][ISI]
Van Hoeken-Klinkenberg, P. M. J. 1966 Maastrichtian, Paleocene and Eocene pollen and spores from Nigeria. Leidse Geologische Mededelingen 38: 37–48
Vassal, J. 1981 Acacieae. In R. M. Polhill and P. H. Raven [eds.], Advances in legume systematics, part 1, 169–171. Royal Botanic Gardens, Kew, Richmond, Surrey, UK
Wieringa, J. J. 1999 Monopetalanthus exit. A systematic study of Aphanocalyx, Bikinia, Icuria, Michelsonia and Tetraberlinia (Leguminosae, Caesalpinioideae). Wageningen Agricultural University Papers 99–4. Wageningen, The Netherlands
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