Re: New 'frog-amander' (today's Nature)

[dinoboygraphics@aol.com]

> > > In fact, if the authors are right, almost everyone's blood will 
flow, because almost all phylogenetic analyses have found a 
monophyletic Lissamphibia.<<<

The authors found a monophyletic Lissamphibia, it was just a lot more 
inclusive...

<chuckle>


Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(800) 455-3466 ext. 230
Cell: (307) 921-8333

www.skeletaldrawing.com


-----Original Message-----
From: David Marjanovic <david.marjanovic@gmx.at>
To: DML <dinosaur@usc.edu>
Cc: LAURIN Michel <michel.laurin@upmc.fr>
Sent: Wed, 21 May 2008 6:12 pm
Subject: Re: New 'frog-amander' (today's Nature)


Ah, so Jason's "stem-batrachian" is out. Congratulations on getting it 
into Nature. Let the massacre begin...Â
Â
(Lots of metaphorical blood will flow over this. I just don't know 
whose. Will be fun to find out. :-) In fact, if the authors are right, 
almost everyone's blood will flow, because almost all phylogenetic 
analyses have found a monophyletic Lissamphibia.)Â
Â
----- Original Message -----Â
From: "Tim Williams" <twilliams_alpha@hotmail.com>Â
To: <dinosaur@usc.edu>Â
Sent: Thursday, May 22, 2008 1:25 AMÂ
Subject: New 'frog-amander' (today's Nature)Â
Â
> Not dinosaurs, but still pretty darn cool...Â
> Â
> Jason S. Anderson, Robert R. Reisz, Diane Scott, Nadia B. FrÃbisch, & 
> Stuart S. Sumida (2004). A stem batrachian from the Early Permian of 
> Texas and the origin of frogs and salamanders. Nature 453: 515-518.Â
> Â
> First paragraph: "The origin of extant amphibians (Lissamphibia: 
frogs, > salamanders and caecilians) is one of the most controversial 
questions in > vertebrate evolution, owing to large morphological and 
temporal gaps in > the fossil record. Current discussions focus on 
three competing > hypotheses: a monophyletic origin within either 
Temnospondyli or > Lepospondyli, or a polyphyletic origin with frogs 
and salamanders arising > among temnospondyls and caecilians among the 
lepospondyls. Recent > molecular analyses are also controversial, with 
estimations for the > batrachian (frogâsalamander) divergence 
significantly older than the > palaeontological evidence supports.Â
Â
This last half-sentence is not true.Â
http://www.informaworld.com/smpp/content~content=a778976765~db=all~order=pageÂ;
Â
> Here we report the discovery of an amphibamid temnospondyl from the 
Early > Permian of Texas that bridges the gap between other Palaeozoic 
amphibians > and the earliest known salientians and caudatans from the 
Mesozoic. The > presence of a mosaic of salientian and caudatan 
characters in this small > fossil makes it a key taxon close to the 
batrachian (frog and salamander) > divergence. Phylogenetic analysis 
suggests that the batrachian divergence > occurred in the Middle 
Permian, rather than the late Carboniferous as > recently estimated 
using molecular clocks,Â
Â
This agrees with the link I gave above.Â
Â
> but the divergence with caecilians corresponds to the deep split 
between > temnospondyls and lepospondyls, which is congruent with the 
molecular > estimates."Â
> Â
> Describes the new stem-batrachian _Gerobatrachus hottoni_ gen. et sp. 
nov. > (Amphibamidae, Temnospondyli). Although put in the Amphibamidae, 
this > group comes out as paraphyletic. As the authors put it, "Our 
analysis > finds _Gerobatrachus_ to be the immediate sister taxon to 
Batrachia (Fig. > 4), with the amphibamids _Doleserpeton_, _Amphibamus_ 
and _Platyrhinops_ > as successively more basal taxa. In addition, the 
oldest known caecilian > _Eocaecilia_ falls within recumbirostrine 
lepospondyls, sister group to > _Rhynchonkos_ and, one step further 
out, the brachystelechids. Thus, the > available morphological evidence 
supports the hypothesis of a diphyletic > origin of extant amphibians 
from Palaeozoic tetrapods, with a separate > origin of the limbless, 
largely fossorial caecilians from within the > lepospondyls, whereas 
Batrachia originates within Temnospondyli."Â
> Â
> Thus, Lissamphibia is buried, with the phylogenetic analysis 
recovering > batrachians (frogs and salamanders) as temnospondyls, 
whereas caecilians > are lepospondyls.Â
> Â
> The discovery is discussed here, with a nice picture of the 
'frog-amander' > _Gerobatrachus_...Â
> Â
> http://www.msnbc.msn.com/id/24761660/Â;
Â
Can't wait to read the paper tomorrow. Â