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(^62) SAMUEL T. TURVEY
Fig. 4. Area cladogram derived from the strict consensus cladogram in Figure 3a. The nodes numbered 1 to 4
are discussed in the text.


2001). These three regions are here interpreted

as representing a single Early Ordovician SE

Asian palaeogeographic area. A restricted

interpretation of Cimmeria is thus employed in

this analysis.

Area assignment was generally straight-

forward, with the exception of some Asian and

Australian taxa. The Himalayan species Caly-

mene nivalis Salter, 1865b was interpreted as

representing Neseuretus by Dean (1967b, 1975),

Fortey & Morris (1982), Morris & Fortey (1985)

and Rabano (1990); examination of the type

material in the Natural History Museum,

London, suggests that this species should instead

be referred to Sarrabesia. 'Synchomalonotus'

sulcatus Kolobova in Sokolov & Yolkin, 1978,

from the Ashgill of Uzbekistan, previously

reassigned to Sarrabesia by Hammann & Leone

(1997), is here interpreted as a species of

Vietnamia. Calvmenesun longinasuta Dean &

Zhou, 1988, from the early Ashgill of the Zap

Valley, SE Turkey, is extremely similar to

Neseuretinus turcicus, and is certainly con-

generic. Several different authors (Banks 1988;

Corbett & Banks 1974; Legg 1976) have

recorded the presence of reedocalymenine taxa

in Australia, but the taxonomic position of these

specimens has remained unclear. Edgecombe et

al. (1999) tentatively assigned some of this

material to Sarrabesia; although other Aus-

tralian material may well represent different

reedocalymenine taxa, only Sarrabesia is

considered to occur in Australia during the

Ordovician in this analysis.

The consensus cladogram indicates that

Neseuretus as currently understood represents

both a paraphyletic and a polyphyletic genus.

Whereas Neseuretus sensu stricto (i.e. Neseuretus

exclusive of N. sanlucasensis, N. intermedius and

N. planus) is known to have occurred in

shallow inner-shelf conditions amenable to high-

resolution biogeographic analysis, and Caly-

menella and Pradoella occupied similar

shallow-water conditions during the Early

Ordovician (e.g. Beckly 1989; Rabano 1990), the

ecological requirements of Middle Ordovician

Asian reedocalymenine taxa, and the species

previously assigned to Neseuretus which occur at

the base of the Neseuretinus-Sarrabesia-

Vietnamia subclade, are less well understood

or are known to have differed. Neseuretinus

turcicus is recorded from offshore shallow shelf
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