Figure 8.Green River paddlefish, †Crossopholis magnicaudatus. More than twelve complete specimens of this taxon are known, al-
though it remains one of the rarest fishes in the Green River Formation (Grande & Bemis 1991).
mented by tabular summaries (Tables 2-5) and il-
lustrations (Figure 5-16).- Family †Chondrosteidae Egerton 1858
†Chondrosteus acipenseroidesAgassiz 1844 from
the Lower Jurassic of England is based on multiple,
complete specimens. Some authors consider the ge-
nus †Srongylosteus(as represented by †S. hinden-
bergiPompeckj 1914 from the Lower Jurassic of
Germany) to be synonymous with †Chondrosteus;
the few reported differences between these genera
need new study. In the absence of modern studies,
papers by Egerton (1858), Traquair (1887) and Hen-
nig (1925) remain useful. Traquair (1887) empha-
sized morphological similarities between †Chon-
drosteusand acipenserids, including jaws free from
the cheek, reduced scales, and reduced ossification,
and his work provided the basis for the classic in-
terpretation that †Chondrosteus and Acipenseri-
dae are sister groups, an interpretation rejected by
Grande & Bemis (1991, also see discussion of node
Acipenseroidei below).
†Gyrosteus mirabilisis known from several in-
complete specimens from the Jurassic of England
(summarized by Woodward 1891,1895a,b,c) whichare not suited for detailed study. These were spec-
tacularly large fish: the ossified portion of one hyo-
mandibula exceeds 50 cm, compared to an entire
hyomandibula only 12 cm long from a two meter
Acipenser oxyrinchus. As far as we can tell, †Gyros-
teusappears to be undiagnosable as a genus distinct
from †Chondrosteus
We used published data on †Chondrosteus
acipenseroidesand †Chondrosteus(= †Strongylos-
teus) hindenbergifrom Egerton (1858), Traquair
(1887) and Hennig (1925) in our phylogenetic analy-
sis.- Family †Peipiaosteidae Liu & Zhou 1965
Yakovlev (1977,1986) does not consider that †Pei-
piaosteidae is distinct from †Chondrosteidae. We
disagree, and find that the two families probably do
not even form a monophyletic group.
Two genera and four nominal species are recog-
nized in †Peipiaosteidae (Table 3). †Peipiaosteusis
known from two very similar species from the Up-
per Jurassic of Northern China. †Peipiaosteus pani
was described from about 40 specimens (Liu &
Zhou 1965). More recently, †P. fengningensiswas
described by Bai (1983). In a recent review, Zhou