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Re: when is a Lazarus Taxon not a Lazarus Taxon?
Mike Taylor wrote:
The age of _Wuerhosaurus_ seems to be given, rather schizophenically, as
"Valanginian or Albian" in Galton and Upchurch 2004. I leave it to lovers
of Chinese stratigraphy to sort that one out :-)
I've seen Valaningian-Albian (i.e., Valanginian TO Albian), which makes more
I've not seen the material so I'm hesitant to be too emphatic about this;
but since the sole _Sonorasaurus_ specimen ADSM-500 was originally thought
to be a hadrosaur (Thayer and Ratkevich 1995) and then a Therizinosaur
(Ratkevich's talk at DinoFest 1997), and since the "nearly complete skull"
turned out to be distorted dorsal, you will forgive me if I am not quick to
believe that the material can be definitively identified as _Brachiosaurus_
The version I heard... The folks who first worked on _Sonorasaurus_ were not
dinosaur experts, and their opinion of this beastie certainly transmogrified
over time. By the time the description was published, it was clear that
_Sonorasaurus_ was a sauropod. However, it was Brian Curtice who remarked
upon how similar _Sonorasaurus_ was to _Brachiosaurus_, and I'd take his
opinion to the bank. Although Curtice did not actually advocate
synonymizing _Sonorasaurus_ with _Brachiosaurus_.
It doesn't seem unreasonable that it should be brachiosaurid, but since the
EK was crawling with putative brachiosaurids, or at least basal
titanosauriforms, that's not surprising.
I'd say "stomping" rather than "crawling". :-) However, given the
incompleteness and the state of preservation of the _Sonorasaurus_ material,
it may just be the case that the *known* material appears brachiosaurid.
There's no doubt that it's a basal titanosauriform, but the taxon is poorly
represented. Galton and Upchurch (2004) actually treat _Sonorasaurus_ as a
nomen dubium, which seems harsh IMHO.
Roberto Takata wrote:
What about Lazarussuchus?
The choristodere _Lazarussuchus_ (Oligocene) was named with this in mind.
Further, if _Lazarussuchus_ is a basal choristodere (as some phylogenetic
analyses have found), it implies a very long ghost lineage indeed.
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