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RE: Yet more fun with squamate phylogeny

Thanks for the plug, David!

Seems like a fair summary; as for coexistence with pythons, that probably
only happened for a relatively 'short' time from the late Oligocene when (I
think) pythons invaded the Lost World (aka Australia): 
*Yurlunggur* and *Morelia* are found together in many Riversleigh LFs and a
few similar-aged sites in the Northern Territory, but probably differed in
being terrestrial vs. arboreal as well as size.  
>From the Pliocene the pythons are more diverse (*Liasis* and *Antaresia*
turn up) and NEVER yet found in the same faunas with *Yurlunggur* or
*Wonambi* (e.g. madtsoiids at Chinchilla, Lake Kanunka, Naracoorte,
Wellington, Wyandotte; pythons at Bluff Downs, Mt Etna & Marmor).  Also,
*Yurlunggur* and *Wonambi* have non-overlapping ranges except for the small
*W. barriei* in the early Mio, so it seems big madtsoiids weren't very good
at sharing. *Morelia* now lives around Wellington, Naracoorte and in
southern WA, but only *Wonambi* has been found in the cave deposits there. 
The record's pretty sparse (this is Australia we're talking about), but to
me it sure looks like competitive exclusion.
Dr John D. Scanlon
Riversleigh Fossil Centre, Outback at Isa
19 Marian Street / PO Box 1094
Mount Isa  QLD  4825
Ph:   07 4749 1555
Fax: 07 4743 6296
Email: riversleigh@outbackatisa.com.au

> -----Original Message-----
> From: David Marjanovic [mailto:david.marjanovic@gmx.at]
> Sent: Thursday, February 16, 2006 8:40 AM
> To: DML
> Subject: Yet more fun with squamate phylogeny
> John D. Scanlon: Skull of the large non-macrostomatan snake *Yurlunggur*
> from the Australian Oligo-Miocene, Nature 439, 839 -- 842 (16 February
> 2006)
> Abstract (refs removed):
> "Understanding the origin and early evolution of snakes from lizards
> depends
> on accurate morphological knowledge of the skull in basal lineages, but
> fossil specimens of archaic snakes have been rare, and either fragmentary
> or
> difficult to study as a result of compression by enclosing sediments. A
> number of Cenozoic fossil snakes from Australia have vertebral morphology
> diagnostic of an extinct group, Madtsoiidae, that was widespread in
> Gondwana
> from mid-Cretaceous (Cenomanian) to Eocene times, and also reached Europe
> in
> the late Cretaceous period. Despite this long history, only about half the
> skull is known from the best-known species *Wonambi naracoortensis*, and
> the
> few known cranial elements of other species have added little further
> evidence for phylogenetic relationships. Conflicting hypotheses have been
> proposed for their relationships and evolutionary significance, either as
> basal ophidians with many ancestral (varanoid- or mosasaur-like) features,
> or advanced (macrostomatan) alethinophidians of little relevance to snake
> origins. Here I report two partial skeletons referred to *Yurlunggur*,
> from
> the late Oligocene and early Miocene of northern Australia, which together
> represent almost the complete skull and mandible. The exceptionally
> preserved skulls provide new evidence linking *Yurlunggur* with *Wonambi*
> and other madtsoiids, falsifying predictions of the macrostomatan
> hypothesis, and supporting the exclusion of Madtsoiidae from the clade
> including all extant snakes."
> In total practically the complete skull is now known -- and full of
> plesiomorphies, many of them relating to limited (but not absent) kinesis.
> The teeth look like a boa's. Riversleigh fossils are preserved in 3D,
> usually undistorted, and can be acid-prepared, as the specimens mentioned
> here were.
> *Yurlunggur* and *Wonambi* each have a few different convergences on
> Macrostomata!
> Madtsoiidae is mentioned to be "presumed to be constrictors ecologically
> analogous to living pythons and boas", followed by a long string of
> references. Don't ask me why they co-occurred with pythons, then...
> Bremer decay index left, bootstrap support right:
> --+--composite "varanoid" outgroup
>   `--+--*Pachyrhachis*
>      `--3,86--*Haasiophis*
>            `--3,67--4,82--*Yurlunggur*
>                  |       `--*Wonambi*
>                  `--5,72--*Dinilysia*
>                       `--11,98--34,100,Scolecophidia (3 OTUs)
>                             `--3,62--3,48,Anilioidea (4 OTUs)
>                                  `--14,99,Macrostomata (10 OTUs)
> The last three lines are the ophidian crown-group (Serpentes), the last
> two
> are called Alethinophidia. The character matrix comes from Lee & Scanlon
> 2002 (abstract:
> http://www.journals.cambridge.org/action/displayAbstract?fromPage=online&a
> id=120939).