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Re: Different twist of BCF



At 05:25 PM 12/2/96 -0500, Caitlin R. Kiernan wrote:

>-Hesperornis- and -Ichthyornis- are traditionally grouped together in the
>superorder Odontognathae (within the orders Hesperornithiformes and
>Ichthyornithiformes, respectively), and I'm under the impression that the
>Enantiornithiformes has ordinal rank, though its relationship to the
>odontognathids is unclear. Has this changed?

Actually, I may have spoken to soon about the relationships of the
enantiornithine birds. According to Feduccia's book "The origin and
evolution of birds", the Hesperornithiform and Ichthyornithiform birds
resemble modern birds and differ from the enantiornithine birds, in that
the distal end of the tarsometatarsus fuses before the proximal end, if
there is a wedge-shaped middle metatarsal, and there is a well-formed
tarsal cap. Thus these birds are really part of the radiation that includes
the modern birds, with the enantiornithine birds more closely resembling
Archaeopteryx. Page 149 presents a cladogram showing Hesperornithiform and
Ichthyornithiform birds with modern birds with outgroups including
Ambiortus, Sinornis and Archaeopteryx. 

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Ronald I. Orenstein                           Phone: (905) 820-7886
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