Li, W.-H. and Grauer, D. (1991) ‘Fundamentals of molecular evolution’, Sunderland, Massachusetts:
Sinauer.
McClure, H.A. (1988) ‘The Ordovician-Silurian boundary in Saudi Arabia’, Bulletin of the British
Museum (Natural History), Geology Series, 43:155–63.
Muse, S.V. (2000) ‘Examining rates and patterns of nucleotide substitutions in plants’, Plant
Molecular Biology, 42:25–43.
Quade, J., Roe, L., DeCelles, P.G. and Ojha, T.P. (1997) The late Neogene^87 Sr/^86 Sr record of
lowland Himalayan rivers’, Science, 276:1828–31.
Raven, J.A. (1997) ‘The role of marine biota in the evolution of terrestrial biota: gases and genes’,
Biogeochemistry, 39:139–64.
Raven, J.A. and Edwards, D. (2001) ‘Roots: evolutionary origins and biogeochemical significance’,
Journal of Experimental Botany, 52:381–401.
Retallack, G.J. (2000) ‘Ordovician life on land and Early Palaeozoic global change’, in
R.A.Gastaldo and W.A.Dimichele (eds) Phanerozoic Terrestrial Ecosystems, Paleontological Society
Papers, 6:21–45.
Richardson, J.B. (1988) ‘Late Ordovician and Early Silurian cryptospores and miospores from
northeast Libya’, in A.El-Arnauti, B.Owens and B.Thusu (eds) Subsurface Palynostratigraphy of
Northeast Libya, Benghazi, Libya: Garyounis University Publications, pp. 89–109.
—— (1992) ‘Origin and evolution of the earliest land plants’, in W.J.Schopf (ed.) Major Events in
the History of Life, Boston: Jones and Bartlett Publishers, pp. 95–118.
Richardson, J.B. (1996) ‘Lower and middle Palaeozoic records of terrestrial palynomorphs’, in
J.Jansonius and D.C.McGregor (eds) Palynology: Principles and Applications, Salt Lake City,
Utah: American Association of Stratigraphic Palynologists, Publishers Press, pp. 555–74.
Richardson, J.B. and Ioannides, N. (1973) ‘Silurian palynomorphs from the Tanezzuft and Acacus
Formations, Tripolitania, North Africa’, Micropalaeontology, 19:257–307.
Richardson, J.B. and Lister, T.R. (1969) ‘Upper Silurian and Lower Devonian spore assemblages
from the Welsh Borderland and South Wales’, Palaeontology, 12:201–52.
Richardson, J.B. and McGregor, D.C. (1986) ‘Silurian and Devonian spore zones of the Old Red
Sandstone Continent and adjacent regions’, Geological Survey of Canada Bulletin, 364: 1–79.
Richardson, J.B., Ford, J.H. and Parker, F. (1984) ‘Miospores, correlation and age of some Scottish
Lower Old Red Sandstone sediments from the Strathmore region (Fife and Angus)’, Journal of
Micropalaeontology, 3:109–24.
Rodríguez-Trelles, F., Tarrío, R. and Ayala, F.J. (2001) ‘Erratic overdispersion of three molecular
clocks: GPDH, SOD, and XDH’, Proceedings of the National Academy of Sciences, USA, 98:
11405–10.
Rogerson, E.C.W., Edwards, D., Davies, K.L. and Richardson, J.B. (1993) ‘Identification of in situ
spores in a Silurian Cooksonia from the Welsh Borderland’, Special Papers in Palaeontology, 49:
17–30.
Rye, R. and Holland, H.D. (2000) ‘Life associated with a 2.76 Ga ephemeral pond?: Evidence from
Mount Roe #2 paleosol’, Geology, 28:483–6.
Sanderson, M.J. (1997) ‘A nonparametric approach to estimating divergence times in the absence
of rate constancy’, Molecular Biology and Evolution, 14:1218–31.
Sanderson, M.J. and Doyle, J.A. (2001) ‘Sources of error and confidence intervals in estimating the
age of angiosperms from RBCL and 18S RDNA data’, American Journal of Botany, 88:1499–516.
Schopf, J.M., Mencher, E., Boucot, A.J. and Andrews, H.N. (1966) ‘Erect plants in the Early
Silurian of Maine’, United States Geological Survey Professional Paper, 550-D:69– 75.
Sherwood-Pike, M.A. and Gray, J. (1985) ‘Silurian fungal remains: probable records of the Class
Ascomycetes’, Lethaia, 18:1–20.
DATING THE ORIGIN OF LAND PLANTS 143