[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

COLIES AND PARROTS



<<Several talks on conodonts - the latest cladograms (Donoghue, Forey 
and Aldridge) are putting conodonts amongst gnathostomes!>>

Is Forey not one of the authors in the original Rosen et. al. paper that 
argued that dipnoans, rather than panderichthyids, are the sister-group 
to tetrapods?  

Speaking of Rosen et al. authors, I just picked up a copy of Brian 
Gardiner's 1993 Cladistics paper where he restates and tweaks his case 
for Haematothermia; a clade consisting of birds and mammals but 
excluding 'pelycosaurs' and 'crocodiles'.  Must be read to be believed.  
He acknowledges that there is evidence for a dinosaur-bird link and 
supports it (dromaeosaurs are the immediate sister to Aves in his 
analysis) and goes as far as saying that all dinosaurs (including 
pterosaurs) are 'stem-group' birds.  He also agrees that theraspids are 
close to mammals and considers them 'stem-group mammals'.  His cladogram 
of 'birds' goes in this order: pterosaurs, ornithischians, sauropods, 
theropods (including, I think, troodontids and other coelurosaurs 
excluding dromaeosaurs), 'carnosaurs', and dromaeosaurs+Aves.  He argues 
that synapsids are descended from diapsid archosaurs (above crocodiles) 
and exclude 'pelycosaurs' (which he considers monophyletic).  The 
synapomorphies of Haematothermia include: opisthopuby; supra-acetabular 
shelf; thecodonty; prominent cnemial crest; and various soft anatomical 
characters.  Needless to say, I don't buy it.

<<Gareth Dyke spoke about new work he is doing on Eocene London Clay 
birds and the relevance it has for the evolution of all neognathans. 
_Prophaethon_ is a pelecaniform after all (according to Gareth's current 
analysis) and is well nested in the group, being close to sulids and 
other advanced taxa. Bird phylogeny afficianados will be very interested 
to hear that Gareth finds _Balaeniceps_ to be within the 
pelecaniforms.>> 

Cool.  I have always suspected of a pelecaniform affinity for 
_Balaeniceps_ but have never really thought it out.  I'm looking forward 
to the paper.  

<<As you may well predict, Stidham's Lance Fm parrot specimen was 
bought up in the question session. In terms of new information on the 
parrot fossil record, this specimen really does not fit as Eocene and 
Oligocene parrots are not like the psittaciform crown group 
(Psittacidae, though some might prefer to name it Psittacoidea) in 
cranial morphology. The new paper on this is:

MAYR, G. and DANIELS, M. 1998. Eocene parrots from Messel (Hessen, 
Germany) and the London Clay of Walton-on-the-Naze (Essex, England). 
_Senckenbergiana lethaea_ 78: 157-177.>>

Interesting.

<<The new Middle Eocene parrot _Psittacopes_ is described in this 
paper. Clear psittaciform characters are evident in the postcrania 
(wing proportions are different from crown-group parrots though), but 
what is remarkable is the skull: very like that of a coly. That is, 
longer and lower than extant parrots, with only a gently curved 
rostrum and a lower jaw nowhere near as deep, or which such a massive 
coronoid, as in psittacids. Parrot cladograms therefore indicate that 
the modern parrot skull did not evolve until after 
quercypsittids, _Psittacopes_ and other primitive taxa: in other words, 
until the Oligocene-Miocene. The Lance Fm element is discordant with the 
phylogeny. I am just unable to give an opinion on it so will shut up 
now.>>

Guess this quashes my statements that we have no idea about what basal 
psittaciform skulls looked like.  I guess it also disproves my 
suggestion that the Lance parrot is a parrot ancestor.  Anyway, 
concerning the coly-like characters in the skull, though I have not read 
the paper (I don't get that journal over here) I can say that this 
supports an old suggestion of psittaciform ancestry: that coliiforms are 
the sisters of parrots.  Susan Berman and Robert Raikow published a 
paper on coliid hindlimb myology in Auk quite a bit ago (Auk 99, 1982; 
41-57) and they found that parrots and colies share a branch of the 
extensor digitorum longus that sends a branch to the hallux as well as 
the first three digits.  Though they cautioned convergence (colies and 
parrots are some of the only birds that hang and do certain other 
strange climbing acts), they argued for a coliiform-psittaciform link.  
Parrots and colies also are the only birds that climb using their beaks.  

Matt Troutman 
m_troutman@hotmail.com


______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com