Re: New Mesozoic vertebrate articles

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: <bh480@scn.org>
Sent: Friday, March 29, 2002 8:58 PM


> Paton, Haddrath and Baker (2002 online). Complete
> mitochondrial DNA genome sequences show that modern birds
> are not descended from transitional shorebirds.
> Proceedings of the Royal Society: Biological Sciences
> (online)
>
> Abstract: To test the hypothesis put forward by
> Feduccia of the origin of modern birds from transitional
> birds, we sequenced the first two complete mitochondrial
> genomes of shorebirds (ruddy turnstone and blackish
> oystercatcher) [...]
> the optimal tree places palaeognath birds as sister to the
> neognaths including shorebirds. [...]

Apparently the authors got so furious when they tried to read Feduccia's
book (I understand that) that they failed to understand what he actually
meant. Feduccia doesn't think that the living derived shorebirds (of course
he doesn't use the term, but "crown group", like "crown group eukaryotes",
would have been a good description) are paraphyletic. He assumes this only
of the Maastrichtian -- Eocene fossils that may or may not be
Charardriiformes, all the way up to *Presbyornis* and *Juncitarsus*, and he
does assume that paleo- and neognaths diverged before the K-T boundary
(after all, there are a few -- very few -- LK neognaths that he accepts),
even though he is certain that the first neognath was some sort of
shorebird.

> we show that the basal
> splits in the bird tree are much older than the Cretaceous-
> Tertiary (K-T) boundary, reinforcing previous molecular
> studies that rejected the derivation of modern birds from
> transitional shorebirds.

This is a better argument against Feduccia... if we can trust this molecular
clock.

> Our mean estimate for the origin
> of modern birds at about 123 million years ago (Myr ago)
> is quite close to recent estimates using both nuclear and
> mitochondrial genes, and supports theories of continental
> break-up as a driving force in avian diversification.

...while tree topology doesn't, according to the latest paper by Joel
Cracraft and the mtDNA phylogeny paper about ratites. :-)
Wait a minute. 123 Ma!?! Real true gulls lived with *Sapeornis* and long
before *Ichthyornis*?

> Not
> only did many modern orders of birds originate well before
> the K-T boundary, but the radiation of major clades
> occurred over an extended period of at least 40Myr ago,
> thus also falsifying Feduccia's rapid radiation scenario
> following a K-T bottleneck.

"Falsifying" is much too strong a word.

> van Dijk, D. Eduard, 2001. Jurassic bipeds that could hop?
> Perch? Pounce? Fly? South African Journal of Science.
> September- October, 2001; 97 (9-10): 373-374.

Interesting, interesting. Thanks for the ref.

> Wilson, Jeffrey A., Malkani, M. Sadiq, Gingerich, Philip
> D., 2001. New crocodyliform (Reptilia, Mesoeucrocodylia)
> >from the upper Cretaceous Pab Formation of Vitakri,
> Balochistan (Pakistan).
> Contributions from the Museum of Paleontology
> University of Michigan. December 31, 2001; 30 (12): 321-
> 336.
> [...] with serrated teeth that interlock to form a zig-
> zag cutting edge.

Like a comic strip monster or *Istiodactylus*? :-)

> Comparisons with crocodyliforms of
> equivalent age indicate that Pabwehshi is a baurusuchid
> mesoeucrocodylian related to Baurusuchus from Brazil and
> Cynodontosuchus from Argentina. Pabwehshi is the first
> baurusuchid known outside South America. It provides
> further evidence of a Cretaceous biogeographic link
> between South America and Indo-Pakistan.

Interesting. Let's wait for some from Madagascar and Australia. :-) -- How
big is *Pabwehshi*?

> Maisch M.W., 2002. A New Basal Lystrosaurid Dicynodont
> >from the Upper Permian of South Africa. Palaeontology 45
> (2):343-359
> Abstract:
> A new genus and species of late Permian dicynodont,
> Kwazulusaurus shakai,

A peaceful plant-eater named after Tshaka Zulu? He must be rotating in his
grave. :-)