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H.-P. Schultze, T. Marss. Revisiting Lophosteus
73
Conclusions
For over 100 years, Lophosteus Pander, 1856 was known only from the upper Pridoli
of one locality, the Ohesaare Cliff on Saaremaa, Estonia. Märss (1986) described a
second species from the lower Pridoli of a second locality on Saaremaa. About 10
years later, Burrow (1995a) and Märss (1997) extended the range of the genus to the
Lochkovian of Australia and the Urals. Since the beginning of this century, the genus
has been known from the lower Ludlow to the upper Lochkovian and from Australia to
the Canadian Arctic and the Urals. The genus falls within the distribution, in time and
paleogeography of the oldest actinopterygian scales (Naxilepis, upper Wenlock – upper
Ludlow, China [Wang and Dong 1989]; Andreolepis, middle Ludlow – lower Pridoli,
Scandinavia [Gross 1968], Baltic region, southern Britain, Asian part of Russia [Märss
2001] and China [Burrow et al. 2000]; Ligulalepis, upper Ludlow to Emsian, Australia
[Schultze 1968, Burrow 1994] and China [Wang and Dong 1989]; Terenolepis, upper
Lochkovian, Australia [Burrow 1995b]; Dialipina, Lochkovian – Emsian, Canadian
Arctic, Siberia [Schultze 1968, 1977, 1992] and Sichuan, China [Burrow et al. 2000]).
Psarolepis (upper Pridoli – upper Lochkovian, China [Zhu and Schultze 1997, Yu 1998])
and the sarcopterygians Onychodus (Pragian, China [Wang 1992], Emsian, China
[Burrow et al. 2000]), and Achoania (Zhu et al. 2001), Youngolepis (Chang 1982), and
Diabolepis (Chang and Yu 1984) appear later (upper Lochkovian, China) as do
Powichthys (Jessen 1975, 1980) and the lungfish Uranolophus (Denison 1968) and
Speonesydrion (Campbell and Barwick 1982).
The 17 characters, which can be collected from Lophosteus, place the genus outside
all osteichthyans, whereas these characters separate actinopterygians and sarcopterygians
within osteichthyans. Lophosteus is the sister group of the acanthodians as suggested
by Otto (1991). One may place it between acanthodians and osteichthyans as a basal
osteichthyan.
Acknowledgments. - The senior author thanks Mr. P. Czaja for the SEM pictures (Figs 3 D, E, 4,
5 B, 6), Dr. St. Schultka for photographs (Fig. 1 A-C) and Mrs. E. Siebert for the drawings (Figs
2 and 7), all from the Museum für Naturkunde, Berlin. T.M. thanks all following institutions and
colleagues. Drs H. Perens and E. Kala, Geological Survey of Estonia, provided the core samples.
The samples from the central Urals were collected by expeditions in the years 1973 to 1986
organized by Drs A. Zhivkovich and P. Chekhovich, Moscow. The 1994 Canadian Arctic
expedition, in which TM participated, was financed by the Polar Continental Shelf Project,
McGill University Northern Studies, the Natural Science and Engineering Research Council,
Canada, the Muséum national d’Histoire naturelle Paris, France, and the UNESCO/IUGS (IGCP
Project 328); participants were Drs M.V.H. Wilson, P.-Y. Gagnier, D. Goujet, M. Caldwell, and
Mr. A. Lindoe. SEM pictures (Figs 3 A-C, 5 A, C) were taken by V. Mikli in the Centre for
Material Research at Tallinn University of Technology. This study was supported by the Estonian
Science Foundation grant 5726 for T.M. Dr. D. Unwin, Berlin, kindly corrected the English.
References
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