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Dinosaur Genera List corrections #139



The JVP article on the systematics of Thecodontosaurus (Benton, Juul, Storrs 
& Galton, 2000) carried something of a surprise with regard to the genus Palae
osauriscus that rates adding an old, old name to the Dinosaur Genera List. 
(This is a follow-up to my comment on this article in the preceding DGL 
correction.)

According to the article, the story begins with Riley & Stutchbury's use of 
the name Palaeosaurus in their 1836 note/abstract describing the small 
prosauropod Thecodontosaurus. The generic name Palaeosaurus was used with two 
species, P. cylindricum and P. platyodon, but unfortunately, the brief note 
does not constitute an adequate description of either species or the genus Pal
aeosaurus, and these taxa must be regarded as nomina nuda in their initial 
appearance. In 1837 they published a second note, in which the species names 
appeared as P. cylindrodon and P. platyodon, and the generic name appeared 
with two different spellings: Palaeosaurus and Paleosaurus. Only in 1840 did 
they at last publish a paper adequately describing the two species, under the 
names Paleosaurus cylindrodon and Paleosaurus platyodon.

Spelling is important here. In 1842, Owen adopted the earlier spelling Palaeos
aurus for this genus, and almost everybody used this spelling ever since. In 
1959, however, Oskar Kuhn discovered that Palaeosaurus is preoccupied by an 
1833 usage for a crocodylian and proposed the replacement name Palaeosauriscus
. This name subsequently became widely accepted. Under present ICZN spelling 
rules, however, the spelling Paleosaurus may be considered distinct from the 
spelling Palaeosaurus, and this name, because the genus under that spelling 
was adequately described in the 1840 Riley & Stutchbury paper, is the correct 
name for this genus. Benton, Juul, Storrs & Galton then sink Palaeosaurus as 
preoccupied and Palaeosauriscus as a junior synonym of Paleosaurus.

In the Dinosaur Genera List, I considered Paleosaurus as simply a respelling 
of Palaeosaurus and left it off, as I do most misspellings that are nomina 
nuda, but the Benton, Juul, Storrs & Galton restudy necessitates adding the 
genus to the list as a separate name. (Because of its wide usage in the 
literature, Palaeosaurus is retained in the list, but as a preoccupied nomen 
nudum.) Unfortunately, Benton et al. show that the material belongs to an 
indeterminate phytosaur, so Paleosaurus is not presently considered 
dinosaurian (although, as Palaeosaurus, it once was) and thus requires an 
asterisk. So I add as genus #884:

Paleosaurus Riley & Stutchbury, 1840*

I do not annotate nomina dubia in the List, only nomina nuda. This name is 
taxonomically valid and unpreoccupied, and so appears in bold italics, even 
though it's a nomen dubium.

In the European dinosaur species list (where I do annotate nomina dubia), the 
entry for Paleosaurus (formerly listed as Palaeosauriscus) reads as follows 
(maximize screen to avoid unsightly turnover lines):

Paleosaurus Riley & Stutchbury, 1840 [nomen dubium]*
    = Palaeosauriscus Kuhn, 1959 [nomen dubium]*
    = Palaeosaurus Riley & Stutchbury, 1836/Geoffroy Saint-Hilaire, 1833 [nome
n nudum]*
    = Paläosaurus T. Plieninger, 1846 [sic]
    = Palaosaurus Reig, 1959 (not 1958) [sic]
    = Paleosaurus Riley & Stutchbury, 1837 [nomen nudum]*
    P. platyodon Riley & Stutchbury, 1840?
        = Palaeosauriscus platyodon (Riley & Stutchbury, 1840) Kuhn, 1959 [nom
en
            dubium]?*
        = Rileya platyodon (Riley & Stutchbury, 1840) von Huene, 1908 [nomen 
dubium]*
        = Thecodontosaurus platyodon (Riley & Stutchbury, 1840) von Huene, 
1908 [nomen
            dubium]*
        = Palaeosaurus platyodon Riley & Stutchbury, 1836 [nomen nudum]*
        = Paleosaurus platyodon Riley & Stutchbury, 1837 [nomen nudum]*
NOTE: The above species is probably a phytosaur (Hunt, 1994). Synonymy within 
this species is according to Benton, Juul, Storrs & Galton, 2000. This 
species was designated the type species of this genus, under the spelling Pale
osauriscus, by Steel (1970). Some material referred to this species under the 
name Rileya platyodon was subsequenty made the type specimen of the species Ri
leyasuchus stutchburyi (as Rileya stutchburi) by von Huene, 1920.
    ?P. cylindrodon Riley & Stutchbury, 1840 [nomen dubium]*
        = Palaeosauriscus cylindrodon (Riley & Stutchbury, 1840) Kuhn, 1959?*
        = Thecodontosaurus cylindrodon (Riley & Stutchbury, 1840) von Huene, 
1908 [nomen
            dubium]*
        = Palaeosaurus cylindricum Riley & Stutchbury, 1836 [nomen nudum]*
        = Palaeosaurus cylindrodon Riley & Stutchbury, 1837 [nomen nudum]*
        = Paleosaurus cylindrodon Riley & Stutchbury, 1837 [nomen nudum]*
        = Palaeosaurus cyclindridon Chure & McIntosh, 1989 [sic]
NOTE: This species is probably a phytosaur (Benton, Juul, Storrs & Galton, 
2000).
    ?P. sternbergii (Fitzinger, 1843) [nomen nudum]*
        = Palaeosauriscus sternbergii (Fitzinger, 1843) [nomen nudum]*
        = Palaeosaurus sternbergii Fitzinger, 1843 [nomen nudum]*
NOTE: This species may belong to the crocodylian genus Palaeosaurus Geoffroy 
Saint-Hilaire, 1833 rather than to the thecodontian genus Palaeosauriscus 
Kuhn, 1959; but because it is a nomen nudum, this issue cannot be resolved. 
It has also been suggested in the literature that it is a captorhinomorph (R. 
E. Molnar, pers. comm.), but again, since the taxon is a nomen nudum, the 
basis for this determination is obscure.
    ?P. stricklandi (Davis, 1881) n. comb. [nomen dubium]*
        = Palaeosauriscus stricklandi (Davis, 1881) Steel, 1970 [nomen dubium]
*
        = Palaeosaurus stricklandi Davis, 1881 [nomen dubium]*
NOTE: The above tooth species is probably phytosaurian.
    ?P. subcylindrodon (von Huene, 1908) n. comb. [nomen dubium]
        = Thecodontosaurus subcylindrodon von Huene, 1908 [nomen dubium]
        = Palaeosauriscus subcylindrodon (von Huene, 1908) Steel, 1970 [nomen 
dubium]
        = Palaeosaurus subcylindrodon (von Huene, 1908) von Huene, 1932 [nomen
 dubium]
        = Thecodontosaurus subcylindrodon von Huene, 1905 [nomen nudum]
NOTE: This species may be a herrerasaurian dinosaur (cf. Galton, 1984).
    Numerous species have over the years been referred to the genera Palaeosau
rus, Palaeosauriscus, and Paleosaurus, which have at times been considered 
dinosaurian. Some of these species may indeed be dinosaurian, but others are 
now considered to be other kinds of archosaurs. Species listed here are those 
not yet referred to other genera; species that at one time or another have 
been referred to this genus but are presently referred to nondinosaurian 
genera are not listed. The new combinations above are simply referrals to 
this genus under the spelling Paleosaurus, adopted as the correct spelling by 
Benton, Juul, Storrs & Galton, 2000. The spelling Palaeosaurus is 
preoccupied, while the replacement name Palaeosauriscus, proposed by Kuhn 
(1959), is unnecessary because the spelling Paleosaurus is available.

AOL users on my mailing list will see the italics and boldface in the above, 
but for other recipients of this mailing, alas, the typography may be 
squelched.