Family †Chondrosteidae
†Chondrosteus - Jurassic, Europe
Figure 5.Reconstruction of †ChondrosteusfromWoodward(1895c). †Chondrosteuslacksbody scales and has a projectile jawsystem.
as the several‘intrinsic’barriers to study described knownfossiltaxashowthat thebasicbodyplans of
in the precedingparagraph. livingsturgeons and paddlefisheswerewellestab-
Our researchprogram onAcipenseriformes em- lished by the end of theCretaceous, andearlier fos-
phasizesgenericlevelrelationshipsusingcompara- silsbelonging toboth of the extantfamilies are be-
tiveosteology anddevelopmentalstudies of the ingfound. Forexample, Lu(1994) recently de-
skeleton andothertissues. Theskeleton provides scribed †Protopsephurus, an UpperJurassic pad-
an excellent source of phylogeneticdatawhich can dlefishfromChina, sothatPolyodontidae is as old
be reliablyrecoveredfromspecimensprepared in as the middleMesozoic. All fossil Acipenseri-
many differentways. Italsoallows us toincorporate formes comefrom thenorthernhemisphere,which
well-preservedfossils,whichgiveotherinsightsinto isconsistentwith theHolarcticrange ofliving spe-
the evolutionary history of actinopterygians. Aci- cies. Finally,althoughsturgeons andpaddlefishes
penseriformes is an old group, knownfrom as far areoften loosely called ‘living fossils’, this does not
back as theLowerJurassic ofEurope.Certainwell- mean that featurespresent inlivingsturgeons and
paddlefishes arenecessarily primitive. Such hy-
Table1.Selected references forsome outgrouptaxa.
Sources of osteologicaldata†Cheirolepis Pearson &Westoll 1979 Egerton1858.
Polypterus
†Mimia Gardiner1984a †ChondrosteusAgassiz 1844
†Moythomasia Gardiner1984a †C.acipenseroidesAgassiz 1844 LowerJurassic-England
†Birgeria Nielsen 1949 †StrongylosteusEgerton 1858
†Saurichthys Rieppel1992. Stensiö 1925 †S.hindenburgiPompeckj 1914 LowerJurassic-Germany
Lepisosteus Wiley 1976 andpers.obs. †GyrosteusAgassiz 1844
Amia Grande &Bemis 1997 †G.mirabilisAgassiz 1844 Jurassic-England
Table2.Species andbiogeographic ranges of†ChondrosteidaeAllis 1922 andpers.obs.