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Dal to the Britta Dal formations that have been cor-
related to the GF to LN spore zones (Marshall et al.
1999) (Fig. 1). The third tetrapod genus (Tetrapoda
n. gen. et sp. on Fig. 1) is less securely dated; it
comes from specimens collected on the south side
of Celsius Bjerg, but it is not possible to assign
these specimens to a precise stratigraphical level
between the Aina Dal and the Britta Dal formations
(see Blom et al. 2007, pp. 132 and 136; Clack et al.
in press).
The East Greenland series highlights a problem:
some of the vertebrate material, including Holopty-
chius sp. and Groenlandaspis mirabilis, has been
collected in the uppermost part of the series
(Bendix-Almgreen 1976; Schultze 1993). The
sixth assemblage or Gr ¨nlandaspis Series (Blom
et al. 2007, p. 136) is assumed to be earliest
Carboniferous in age. This Gr¨nlandaspis Series
or Gr ¨nlandaspis Group is stratigraphically above
the black shales (of the Obrutschew Bjerg
Formation) containing actinopterygian material
(Cuneognathus gardineri, Friedman & Blom
2006) which marks the Devonian - Carboniferous
boundary on the south side of Celsius Bjerg (Mar-
shall et al. 1999; Blom et al. 2007, pp. 128 - 129).
This would therefore correspond not only to the
only record of these taxa (Holoptychius and Groen-
landaspis) in the Carboniferous (Blom et al. 2007,
p. 128), but also to the only record of post-Devonian
porolepiform sarcopterygians and placoderms.
This point concerns a more general problem of
dating the last occurring placoderms which are
usually assumed not to have survived the Devonian
(see dating some of the Late Devonian Old Red
Sandstone-like localities of Australia - references
in Denison 1978; Long 1993; Young 1993, 2006,
2007). According to Blom et al. (2007), in East
Greenland it is either a problem of taxonomic identi-
fication of the material or of dating the Devonian -
Carboniferous boundary (DCB) in the stratigraphi-
cal sequence (or both). Indeed, the assertion that
“the Devonian - Carboniferous boundary can be
confidently placed within the Obrutschew Bjerg
Formation” (Marshall et al. 2002) can be chal-
lenged. The miospore/conodont data in the Sauer-
land (Germany) demonstrate that the LN/VI
miospore boundary level is clearly below but not
at the DCB. The Obrutschew Bjerg Formation
might well be entirely Devonian (Streel & Marshall
2006, table 2, level 15).
considered Late Famennian in age (Pan et al.
1987). This formation is well known for its fish
assemblage together with plants and miospores.
The fish assemblage is known as the Sinolepis
assemblage (Macrovertebrate Assemblage XI of
Zhu et al. 2000) and it includes Galeaspida indet.,
Bothriolepis sp., Remigolepis major, R. microce-
phala, R. sp., R. xiangshanensis, R. xixiaensis, R.
zhongmingensis, R. zhongweiensis, Sinolepis szei
and Sarcopterygii indet (Pan et al. 1987; Zhu
2000). In this assemblage Sinolepis is a typically
endemic placoderm genus for China and Australia
(Ritchie et al. 1992). This assemblage with Remigo-
lepis and Bothriolepis is comparable to that in east
Greenland where it spans both the Frasnian and
Famennian (Blom et al. 2007).
Miospores have also been prepared from the
Zhongning Formation and published by Gao (Pan
et al. 1987). They come from the topmost part of
the Shixiagou section (bed 27) of the Zhongning
Formation, and thus constrain the age of the top of
this formation. Among them, on a total of 32
species, some have a more significant biostratigra-
phical value such as Apiculatisporites microconus,
Geminospora lemurata, Verruciretusispora magni-
fica and Archaeozonotriletes variabilis (Pan et al.
1987). The age of this assemblage is within the int-
erval Mid Givetian to Frasnian (Ritchie et al. 1992)
or probably Frasnian (S. Loboziak pers. comm.,
1989) and not Famennian (Blieck et al. 2007).
This dating of the Zhongning Formation has a
consequence in the interpretation of the Frasnian -
Famennian (FF) biotic event (crisis). If Famennian
in age, the galeaspid of the Zhongning Formation
would be the only post-Frasnian ostracoderm
confirmed (e.g. Blieck 1991; Janvier & Blieck
1993; Janvier 1996). However, if the Zhongning
Formation is Frasnian in age, as we believe,
there is no post-Frasnian galeaspid in China, no post-
Frasnian ostracoderm worldwide and the FF event is
an actual crisis for armoured jawless vertebrates.
Comments on the SE Australian localities
Three tetrapod-bearing localities (two with track-
ways and one with Metaxygnathus; see Fig. 1) are
known from the Devonian of Victoria and New
South Wales, SE Australia (Young 2006, 2007).
The Genoa River fish-tetrapod trackway assemblage
(Bothriolepis sp., Remigolepis sp., Groenlandaspis
sp., an osteolepiform and two tetrapod trackway
types; Warren & Wakefield 1972; Clack 1997,
2002; Young 2007) comes from the Combyingbar
Formation (formerly known as the Genoa River
beds) of easternmost Victoria. This formation is
aligned with the Twofold Bay Formation of
southeastern-most New South Wales, and is there-
fore dated as Frasnian (Young 2007) as originally
Comments on the North Chinese locality
Zhu et al. (2002) have published a locality of Late
Devonian age from the Ningxia autonomous
region of NW China, with a partially preserved
mandible
called
Sinostega.
It
comes
from
the
Zhongning
Formation
which
is
classically
