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FW: For DML: Calamospondylus etc.



Darren Naish asked me to send the following:

------------------------------
The following email might seem horribly pedantic. There?s
a minor issue in Cretaceous theropod taxonomy that people
keep getting wrong, and having just seen this mistake
perpetuated by Novas et al. (2004) in their revision of the
Lameta Formation abelisauroids, I?d like to take this
opportunity to restate the case and bring the updated,
corrected version of this issue to wider attention. I am, of
course, talking about the obscure Lower Cretaceous English
theropods _Calamospondylus_, _Calamosaurus_ and
_Aristosuchus_. Those of you familiar with my writings
(both to DML and in the literature) on these taxa (or,
indeed, those of you unfamiliar with such) may find the
following tedious to the extreme but, as I said, it seems that
the following story is still not that widely known.

In their discussion of _Laevisuchus_ (p. 80), Novas et al.
(2004) wrote ?Norman (1990: 302), following Huene and
Matley (1933: 60-61), pointed out that the vertebra of
_Laevisuchus_ resembles that of ?_Aristosuchus_? (junior
synonym of _Calamospondylus_ Fox, 1866)?. Note use of
the convention of putting ostensible nomina dubia into
quotes. Ok, here are the problems: (1) the cervical vertebrae
that Norman (1990) was referring to were not those of
_Aristosuchus_, and (2) _Aristosuchus_ is not a junior
synonym of _Calamospondylus_.

The cervical vertebrae involved in this particular mess are
BMNH R901, the two Wessex Formation cervicals
described by Lydekker (1889) as representing the new
taxon _Calamospondylus foxi_ (and not _Calamospondylus
foxii_ [sic] as wrongly stated in Naish et al. 2001).
Bizarrely, Lydekker (1891) later explained that he had, in
1889, been completely unaware of the fact that the name
_Calamospondylus_ had already been coined for another
Lower Cretaceous Isle of Wight dinosaur, this taxon being
_Calamospondylus oweni_ Fox, in Anon. 1866. Because,
therefore, Lydekker had not intended _Calamospondylus
foxi_ to be congeneric with _Calamospondylus oweni_
(their synonymy being, apparently, an unfortunate
coincidence), in 1891 he proposed the new genus
_Calamosaurus_ for BMNH R901. The most recent author
to think that _Calamosaurus_ might be congeneric with
_Calamospondylus_ was Rauhut (2003) so far as I know
(see his specimen list, p. 202, and ? as suggested by Naish
2003 ? go to p. 201 and look for the joke while you?re
there).

_Calamospondylus oweni_ Fox, in Anon. 1866 (and note,
not actually ?Fox 1866? [because Fox didn?t write the article
himself ? an anonymous editor did]) was named for sacral
vertebrae and associated pelvic bones. For most of history it
has been assumed that the specimen Fox was referring to
was BMNH R178, a specimen named _Poikilopleuron [sic]
pusillus_ by Owen (1876) but later removed from
_Poekilopleuron_ (note correct spelling) and given its own
genus, _Aristosuchus_, by Seeley (1887). BMNH R178
consists of five sacral vertebrae and two distally conjoined
pubic bones and most authors have been happy with the
idea that it is a compsognathid similar to _Compsognathus_
(Olshevsky 1991, Naish et al. 2001, 2004, Hutt et al. 2001,
Naish 2002, Rauhut 2003, Hwang et al. 2004).

However, as is explained in full in Naish (2002), it is clear
from Fox?s letters to Owen (and from various other clues)
that _Calamospondylus oweni_ was NOT named for
BMNH R178, the holotype of _Aristosuchus_. The few
details given in the brief communication on
_Calamospondylus oweni_ are not sufficient to determine
whether or not the specimen was diagnostic, and
furthermore the specimen is of unknown whereabouts right
now. Accordingly, _Calamospondylus oweni_ is a nomen
dubium based on a lost specimen, but it is _not_
demonstrably synonymous with _Aristosuchus_ (note that
_Calamospondylus oweni_ is a nomen dubium, and not a
nomen nudum as argued by Naish et al. 2001).

So? (well done if you?ve made it this far), what does this
mean, in the simplest terms?

-- _Calamospondylus oweni_ Fox, in Anon. 1866, is a
nomen dubium based on a lost specimen. It was NOT
named for BMNH R178, the holotype of _Aristosuchus_,
and thus it is not correct (at least, so far as we know based
on present data) to say that _Aristosuchus_ is a junior
synonym of _Calamospondylus oweni_, as was stated or
assumed by Norman (1990), Novas et al. (2004) and a
whole list of other authors (Weishampel 1990, Insole and
Hutt 1994, Blows 1998, Kirkland et al. 1998).

-- _Aristosuchus pusillus_ (Owen 1876), based on BMNH
R178, was NOT based on the specimen already named
_Calamospondylus oweni_ by Fox. This was shown by
Naish (2002). It might seem a bit odd that both specimens
consist mostly of sacral vertebrae. However,
_Ornithodesmus cluniculus_ from the Wessex Formation is
also based on a sacrum. _Aristosuchus_ is probably a
compsognathid?. or, at least, it was until _Dilong_came
along :)

-- _Calamosaurus foxi_ (Lydekker 1889) is based on the
two cervical vertebrae BMNH R901. Though originally also
given the generic name _Calamospondylus_, given that
there is no overlap with the holotype of _Calamospondylus
oweni_, and given that the holotype of the latter is lost
anyway, there is no way of knowing whether
_Calamosaurus_ and _Calamospondylus oweni_ are
synonymous. Believe it or don?t, there are presently three
soon-to-appear papers on _Calamosaurus_ and its referred
material. For this reason (as some of you know) it?s best if
public discussion of this taxon is kept to a minimum for the
time being.

And given that the above wasn?t simple enough, here are
things restated in even simpler terms?

-- _Calamospondylus oweni_ Fox, in Anon. 1866, is not
based on the same specimen as _Aristosuchus pusillus_
(Owen 1876) and it is not correct to state that the two are
synonymous.

-- _Calamosaurus foxi_ (Lydekker 1889) cannot be
assumed to be the same thing as _Calamospondylus oweni_.

Given that science is self-correcting, all of this horrendous
mess will one day be resolved definitively when a near-
complete Wessex Formation small theropod skeleton is
described (and, note, I said described and not discovered?
cough cough choke). _Eotyrannus_ and other taxa will
probably prove to be involved as well, but let?s keep
speculation on that to a minimum too. Trying to resolve
Wealden theropod taxonomy has been (as a reviewer once
stated) an ?unenviable task?, but someone had to do it.

Refs --

Anon. 1866. Another new Wealden reptile. _The
Athenaeum_ 2014, 740.

Blows, W. T. 1998. A review of Lower and Middle
Cretaceous dinosaurs of England. _New Mexico Museum
of Natural History_ 14, 29-38.

Hutt, S., Naish, D., Martill, D. M., Barker, M. J. &
Newbery, P. 2001. A preliminary account of a new
tyrannosauroid theropod from the Wessex Formation (Early
Cretaceous) of southern England. _Cretaceous Research_
22, 227-242.

Hwang, S, H., Norell, M. A., Ji, Q. & Gao, K. 2004. A large
compsognathid from the Early Cretaceous Yixian
Formation of China. _Journal of Systematic Palaeontology_
2, 13-30.

Insole, A. N. & Hutt, S. 1994. The palaeoecology of the
dinosaurs of the Wessex Formation (Wealden Group, Early
Cretaceous), Isle of Wight, southern England. _Zoological
Journal of the Linnean Society_ 112, 197-215.

Kirkland, J. I., Britt, B. B., Whittle, C. H., Madsen, S. K. &
Burge, D. L. 1998. A small coelurosaurian theropod from
the Yellow Cat Member of the Cedar Mountain Formation
(Lower Cretaceous, Barremian) of eastern Utah. _New
Mexico Museum of Natural History and Science Bulletin_
14, 239-248.

Lydekker, R. 1889. On a coeluroid dinosaur from the
Wealden. _Geological Magazine_ (Decade 3) 6, 119-21.

- . 1891. On certain ornithosaurian and dinosaurian remains.
_Quarterly Journal of the Geological Society, London_ 47,
41-44.

Naish, D. 2002. The historical taxonomy of the Lower
Cretaceous theropods (Dinosauria) _Calamospondylus_ and
_Aristosuchus_ from the Isle of Wight. _Proceedings of the
Geologists? Association_ 113, 153-163.

- . 2003. [Review of] The Interrelationships and Evolution
of Basal Theropod Dinosaurs. _Geological Magazine_ 140,
729.

- ., Hutt, S. & Martill, D. M. 2001. Saurischian dinosaurs 2:
Theropods. In Martill, D. M. & Naish, D. (eds) _Dinosaurs
of the Isle of Wight_. The Palaeontological Association
(London), pp. 242-309.

- ., Martill, D. M. & Frey, E. 2004. Ecology, systematics
and biogeographical relationships of dinosaurs, including a
new theropod, from the Santana Formation (?Albian, Early
Cretaceous) of Brazil. _Historical Biology_ 2004, 1-14.

Norman, D. B. 1990. Problematic Theropoda:
?coelurosaurs?. In Weishampel, D. B., Dodson, P. &
Osmólska, H. (eds) _The Dinosauria_. University of
California Press (Berkeley), pp. 280-305.

Novas, F. E., Agnolin, F. L. & Bandyopadhyay, S. 2004.
Cretaceous theropods from India: a review of specimens
described by Huene and Matley (1933). _Rev. Mus.
Argentino Cienc. Nat., n.s._ 6, 67-103.

Olshevsky, G. 1991. _A Revision of the Parainfraclass
Archosauria Cope, 1869, Excluding the Advanced
Crocodylia_. Publications Requiring Research (San Diego),
pp. 196.

Owen, R. 1876. Monograph of the fossil Reptilia of the
Wealden and Purbeck Formations. Supplement 7.
Crocodilia (_Poikilopleuron_), Dinosauria
(_Chondrosteosaurus_). _Palaeontographical Society
Monograph_ 30, 1-7.

Rauhut, O. W. M. 2003. The interrelationships and
evolution of basal theropod dinosaurs. _Special Papers in
Palaeontology_ 69, 1-213.

Weishampel, W. B. 1990. Dinosaurian distribution. In
Weishampel, D. B., Dodson, P. & Osmolska, H. (eds) _The
Dinosauria_. University of California Press (Berkeley), pp.
63-139.

--
Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

http://web.port.ac.uk/departments/sees/staff/NaishD.htm
email: darren.naish@port.ac.uk
tel: 023 92846045

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796