Deep Time Project: A Comprehensive Phylogenetic Tree of Living and Fossil Angiosperms

Comments and questions: Dr. Doug Soltis

Last modified: May 9, 2002

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DEEP TIME - DATING DIVERGENCES


Molecular Data

    The ages of major lineages of green plants, including the age of land plants, vascular plants, seed plants, angiosperms, and various groups within the angiosperms (e.g., eudicots), have been debated extensively.  In the past 10-15 years attempts have been made to provide such estimates based on the hypothesis of a molecular clock.  Considering the angiosperms alone, relevant references include Martin et al. (1989, 1993), Wolfe et al. (1989), Goremykin al. (1997), and Sannderson and Doyle (2001).  Recent reviews of such efforts for seed plants and land plants are provided in Sanderson et al. (2000), Sanderson and Doyle (2001), and Soltis et al. (submitted).
   
    Molecular clock estimates typically conflict with both the fossil record and each other, often substantially so and typically provide estimates that are "too old" (i.e., older than any available fossil evidence; reviewed by Sanderson and Doyle 2001).  Some molecular clock estimates appear to be way too old.  For example, in a recent paper  (Heckman et al., 2001) a molecular clock estimate of 700 million years ago (mya) was provided for the first land plants, while the oldest known fossils are only about 400-450 mya.  This type of spurious result calls into question the utility of a molecular clock for dating divergences. 

    Recent efforts have attempted to address the sources of error in estimating the age of lineages using molecular data (Sanderson and Doyle, 2001; Soltis et al. submitted).  Sources of error include inaccurate calibration, an incorrect topology, heterogeneous rates of evolution, and inadequate sampling of taxa (reviewed in Sanderson and Doyle, 2001; Soltis et al., submitted).  Alternative methods, designed to accommodate rate inconstancy, have been proposed, such as non-parametric rate smoothing [NPRS (Sanderson, 1998), likelihood methods (e.g. Yoder and Yang, 2000), and Bayesian methods (e.g. Huelsenbeck et al., 2000)].

    In considering the age of a lineage, it is also important to keep in mind that any extant group has two ages:  the age at which its stem lineage (see B in figure below) branched from the line leading to its extant sister group and the age of the crown group (see A in figure below), which is the age of the most recent common ancestor of the living members (fig. 1).  This issue can have a major impact on age considerations; however, age estimates are often provided without consideration of this issue (see Sanderson and Doyle, 2001). 

Figure 1.  Crown group (A) and stem lineage (B).


    The most careful consideration of the use of molecular data in estimating the age of the angiosperms and sources of error is that of Sanderson and Doyle (2001).  They obtained a wide range of estimates from 68-281 mya, but most are 140-190 mya (Early Jurassic - Early Cretaceous), which overlaps estimates based on the fossil record (Sun et al., 1999, submitted).  Wikstrom et al.  (2001) used NPRS to provide estimates of the ages of most angiosperm clades.  Some of these estimates are provided in Table 1.  Whereas some estimates are close to those based on the fossil record, many of the molecular estimates are older than fossil estimates (see below).


Table 1.  Age of eudicot clades

Minimum age for major eudicot clades, as documented by their earliest occurrence in the fossil record. Earliest records for clades are taken from the earliest appearance of the oldest family included in each clade, from Collinson et al. (1993), and other sources (see main text). Time scale is based on Harland et al. (1989). Eudicot clades without a known fossil record are not included. Names in parentheses after the age indicate the specific taxon on which minimum age is based. Table modified from Magallón-Puebla et al. (1999).

Taxon

Minimum Age

MYBP

Ranunculales (Menispermaceae) Maastrichtian 69.5
Nelumbonaceae Late Albian 100
Platanaceae Early Albian 108
Proteaceae mid-Cretaceous 97
Sabiaceae Maastrichtian 69.5
Buxaceae mid-Albian 104.5
Trochodendrales Aptian (Tetracentraceae) 118
Caryophyllales (Amaranthaceae) Santonian-Campanian (Amaranthaceae) 83
Saxifragales Turonian (Saxifragaeleans) 89.5
Geraniaceae Late Miocene (pollen) 7.8
Brassicales Turonian (Brassicales) 89.5
Sapindales Late Maastrichtian (Rutaceae, Aceraceae) 67.2
Malvales Maastrichtian (Bombacaceae, pollen) 69.5
Myrtales Late Santonian (Myrtales) 84
Cucurbitales Late Paleocene 58.5
Urticales Maastrichtian (Celtidoideae) 69.5
Rosaceae Middle Eocene 44.3
"higher" Hamamelididae Late Santonian (Normapolles flowers) 84
Polygalaceae Late Paleocene 58.5
Mimosoideae Middle Eocene 44.3
Papilionoideae Early Eocene 53.2
Cunoniaceae Late Paleocene 58.5
Malphghiales Late Paleocene 58.5
Cornales Maastrichtian (Mastixiaceae) 69.5
Ericales Turonian (Ericaceae) 89.5
Aquifoliales Maastrichtian (Ilex) 69.5
Apiales Maastrichtian (Araliaceae) 69.5
Dipsacales Early Eocene (Caprifoliaceae) 53.2
Asterales Oliogocene (Asteraceae, Goodeniaceae [pollen], Menyanthaceae) 29.3
Garryales Middle Eocene (Eucommia) 45.9
Boraginaceae Early Eocene (Boraginaceae) 53.2
Solanales Early Eocene (Convolvulaceae) 53.2
Gentianales Early Eocene (Apocynaceae, Rubiaceae) 53.2
Lamiales Late Eocene (Scrophulariaceae, Oleaceae 37
Santalales Early Eocene (Olacaceae) 53.2
Dilleniaceae Early Eocene 53.2
Vitis-Leeaceae Late Paleocene 58.5
Gunneraceae Turonian (pollen) 89.5

 

Fossil Record

    Lycophytes  (377.4 mya; also less conservatively 400 mya).  The earliest record of lycopsids (which includes the extant genera Huperzia, Selaginella, and Isoetes) and also the more inclusive lycophytes is provided by the genus Baragwanathia from the Upper Silurian (Ludlow, 424-410.7 mya), of Australia (Kenrick and Crane, 1997).  From the lowermost Devonian onwards (Lochkovian, 408.5-396.3 mya), both lycophytes and lycopsids are extensively represented.  Based on the topology presented by Kenrick and Crane (1997), a conservative estimate for the crown group lycopsids is given by the first appearance of plants referable to the ligulate lycopsids, such as Leclerquia (Grierson and Bonamo, 1979), which is known from the Middle Devonian (Givetian, 380.3-377.4 mya). [This material is from Soltis et al., submitted.]

    Gymnosperms  (290 mya).  The most ancient seed plants are known from the uppermost Devonian (Fameunnian, 367-362.5 mya) based on well-preserved permineralized seeds (Rothwell and Scheckler, 1988).  However, phylogenetic analyses based on morphological data suggest that the common ancestor of extant seed plants may be considerably younger (e.g., Crane, 1985; Doyle, 1996).  A more conservative estimate of the age of crown group seed plants (or gymnosperms in topologies in which this group is monophyletic) is provided by the first appearance of an extant seed plant lineage.  Scattered reports of conifer leaves and shoots are known from the Westphalian B (approximately equivalent to the Kashirskian, 309.2-307.1 mya), but unequivocal conifers with well-preserved female cones (e.g., Emporia lockardii; Mapes and Rothwell, 1984, 1991) are first recorded from around the Carboniferous-Permian boundary (290 mya).  Subsequently conifers are extensively represented through the Permian and Mesozoic.  Fossil cycad megasporophylls also first appear in the fossil record during the early Permian (Asselian, 290-281.5 mya). [This material is from Soltis et al., submitted.]

    Angiosperms (125-131.8 mya).  A conservative estimate is provided by a variety of fossils from the Barremian-Aptian boundary (125 mya) in the Early Cretaceous.  A less conservative estimate of 131.8 mya is provided by pollen grains from the Hauterivian (Doyle, 1992; Hughes, 1994; Friis et al., 1999; Brenner, 1996). [This material is from Soltis et al., submitted.] Sun et al. (1998) proposed an origin of 144 mya for the angiosperms based on the discovery of Archaefructus, which would place flowering plants in the late Jurassic.  However, this record has been redated as Early Cretaceous (Swisher et al., 1999).  Sun et al. (submitted) later revised the age for Archaefructus to range from 144 mya to a youngest estimate of 125 mya.  125 mya remains the most conservative estimate of the age of the angiosperms.

    Eudicots Magallón et al. (1999) compiled estimates of the minimum ages of major eudicot clades based on the earliest well-documented appearance of these groups in the fossil record.  Many of these estimates are provided on the best current estimate of angiosperm phylogeny (Soltis et al., 2000) in Figure 2 and also in Table 1.  Dates for several lineages of basal angiosperms have also been added to Figure 2.

Figure 2. Minimum ages of major eudicot clades and several lineages of basal angiosperms.




References

Brenner, G.  (1996)  in Flowering Plant Origin, Evolution, and Phylogeny, eds. Taylor, D. W. & Hickey L. J. (Chapman and Hall, New York), pp. 91-115.

Crane, P. R.  (1985)  Ann. Missouri Bot. Gard. 72: 716-793.

Crane, P. R. & Dilcher, D. L. (1984). Lesqueria: an Early Angiosperm Fruiting Axis from the
Mid-Cretaceous. Annals Mo. Bot. Gd. 71(2): 384-402.

Dilcher, D. L. (1989). "The occurrence of fruits with affinities to Ceratophyllaceae in Lower and mid-Cretaceous sediments." American Journal of Botany 76: 12.

Dilcher, D. L. & Crane, P. R. (1984). Archaeanthus: An Early Angiosperm from the Cenomanian of the Western Interior of North America. Annals Mo. Bot. Gd. 71(2): 351-383.

Doyle, J. A.  (1996)  Int. J. Plant Sci. 157 (Suppl.), S3-S39.

Doyle, J. A.  (1992)  Cret. Res. 13: 337-349.

Doyle, J. A. & Hotton, C. L.  (1991) in Pollen and Spores:  Patterns of Diversification, eds. Blackmore, S. & Barnes, S. H. (Systematics Association Special Volume 44, Clarendon Press, Oxford), pp. 169-195.

Friis, E. M., Pedersen, K. R. & Crane, P. R.  (1999)  Ann. Missouri Bot. Gard. 86:259-296.

Friis, E. M., Pedersen, K. & Crane, P. R.. (2001). Fossil evidence of water lilies (Nymphaeales) in the Early Cretaceous.Nature 410: 357-360.

Gao, Z. & Thomas, B. A.  (1989)  Rev. Palaeobot. Palynol. 60: 205-233.

Goremykin, V. Hansmann, S. & Martin, W. (1997) Plant Syst. Evol. 206: 337-351.

Herendeen, P. S. & Crane, P. R. (1995). The fossil history of the monocotyledons. Monocotyledons: Systematics and Evolution. P. J. Rudall, P. J. Cribb, D. F. Cutler and C. J. Humphries, Kew: Royal Botanical Garden: 1-21.

Herendeen, P. S., Crepet, W. L. & Nixon, K. C. (1994). Fossil flowers and pollen of Lauraceae from the Upper Cretaceous of New Jersey. Plant Systematics and Evolution 189: 29-40.

Huelsenbeck, J. P., Larget, B. & Swofford, D. L. (2000) Genetics 154:1879-1892.

Hughes, N. F.  (1994)  The Enigma of Angiosperm Origins (Cambridge University Press, Cambridge).

Larouche, J., Li, P. & Bousquet, J. (1995) Mol. Biol. Evol. 12:1151-1156.

Magallón-Puebla, S., Herendeen, PS, Crane, PR. (1999). Ann. Missouri Bot. Gard. 86: 297-372.

Mapes, G. & Rothwell, G. W.  (1984)  Palaeontol. 27: 69-94.

Mapes, G. & Rothwell, G. W.  (1991)  N. Jahrb. Geol. Palaontol. Abh. 183:269-287.

Martin, W., Gierl, A. & Saedler, H. (1989) Nature (London) 339:46-48.

Martin, W., Lydiate, D., Brinkmann, H., Forkmann, G., Saedler, H. & Cerff, R. (1993) Mol. Biol. Evol. 10:140-162.

Pedersen, K. R., Crane, P. R., Drinnan, A. N. & Friis, E. M. (1991). Fruits from the mid-Cretaceous of North America with pollen grains of the Clavatipollentites type. Grana 32: 273-289.

Pryer, K. M., Schneider, H., Smith, A. M., Cranfill, R., Wolf, P. G., Hunt, J. S. & Sipes, S. D. (2001) Nature (London) 409:545-648.

Rothwell, G. W. & Scheckler, S. E.  (1988) in Origin and Early Evolution of Gymnosperms, ed. Beck, C. B. (Columbia University Press, New York), pp. 85-134. 

Sanderson, M. J. & Doyle, J. A. (2001) Am. J. Bot. 88:1499-1516.

Sanderson, M. J. (1997) Mol. Biol. Evol. 14:1218-1231.

Sanderson, M. J. (1998) in Molecular Systematics of Plants II, eds. Soltis, D. E., Soltis, P. S. & Doyle, J. J.  (Kluwer, Boston, MA), pp. 242-264.

Sun, G. Dilcher, D. L., Zheng, S., & Zhou, Z. 1998.  In search of the first flower: A Jurassic angiosperm, Archaefructus, from Northeast China. Science 282:1601-1772.

Wolfe, K. H., Gouy, M., Yang, Y.-W., Sharp, P. M. & Li, W.-H. (1989) Proc. Natl. Acad. Sci. USA 86, 6201-6205.

Yoder, A. D. & Yang, Z. (2000) Mol. Biol. Evol. 17, 1081-1090.


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