Again, something I noticed while cataloging past
Coelophysis diagnoses. Back in 1887, Cope noted that what would be named
Coelophysis (
Coelurus longicollis and
bauri at the time) differs from
Anchisaurus (his
Megadactylus) and
Megalosaurus in lacking an ectocondylar tuber on the femur. This is also mentioned as a diagnostic character in his 1889 note naming
Coelophysis. This caught my eye since I had just dealt with ectocondylar tubers for
Kayentavenator. So I checked Huene's (1906, 1915) papers describing and illustrating the original
Coelophysis material, and indeed the complete syntype femur of
C. longicollis (AMNH 2704) lacks an ectocondylar tuber. This is unlike theropods (or shuvosaurids, which
C. bauri syntype femur AMNH 2725 was referred to by Nesbitt et al., 2007), but is similar to silesaurids like
Silesaurus and
Eucoelophysis. Also like silesaurids but unlike theropods, the femoral head is parallelogram-shaped instead of distinctly offset. Rather unsurprisingly, it seems to have autapomorphies of the contemporaneous
Eucoelophysis (after Ezcurra, 2006)- no trochanteric shelf, reduced fourth trochanter.
 |
| Femora in lateral and anterior view of (left to right) Silesaurus (after Dzik, 2003), Eucoelophysis (after Ezcurra, 2006), Coelophysis longicollis syntype AMNH 2704 (after Huene, 1915), and Coelophysis bauri with proximal lateral view of kayentakatae (after Spielmann et al., 2007 and Rowe, 1989 respectively). |
This underscores the fact Cope's original
Coelophysis material can't be assumed to be a single taxon. We now have
Coelophysis bauri (cervical AMNH 2701),
Eucoelophysis baldwini (femur AMNH 2704), Shuvosauridae (femur AMNH 2725),
Dromomeron romeri (femur AMNH 2721- Nesbitt et al., 2009) and Parasuchia (teeth AMNH 2733- Padian, 1986). Yet it also shows that some of the material IS diagnostic, people just have to bother actually examining it.
We now have...Eucoelophysis baldwini
ReplyDeleteNo we don't, we have Eucoelophysis longicollis ;-). Or has a different, non-conspecific part of the C. longicollis type series been designated as lectotype?
Just by way of a reminder: Longosaurus longicollis does not have the same type specimen as Coelophysis longicollis, correct? So Coelophysis longicollis is not the type species of Longosaurus?
The cervical referrable to Coelophysis bauri which I discussed in the last post is the lectotype of longicollis. Again, it's funny how wrong Hunt and Lucas were that it didn't matter which syntype they chose for a lectotype, since they were all supposedly undiagnostic. Though really the cervical is the best lectotype because Cope's diagnosis for the species is based on it, as is the name itself.
ReplyDeleteAnd yes, Longosaurus longicollis' lectotype is an ilium chosen by Welles (1984) which is not viable as a lectotype for C. longicollis since it was not one of Cope's syntypes. So Welles intended for Longosaurus to be a new genus for C. longicollis but goofed.