Re: Basal Hadrosauroidea

[João Simões Lopes Filho <jodan99@uol.com.br>]

But Ouranosaurus can be considered a true hadrosaur? I've read articles
putting it as a basal member of the linneage, a sort of "missing link"
between iguanodonts and hadrosaurs.
Joao SL
Rio
----- Original Message -----
From: Jaime A. Headden <qilongia@yahoo.com>
To: <dinosaur@usc.edu>
Sent: Sunday, October 01, 2000 12:03 AM
Subject: Basal Hadrosauroidea


>   I notice that *Eolambia* (Albian-Canomanian),
> *Telmatosaurus* (u.Campanian?-l.Maastrichtian?),
> *Protohadros* (m.Cenomanian), *Secernosaurus* (Upper
> Cretaceous: Brett-Surman, 1979), *Gilmoreosaurus*
> (u.Cenomanian?-l.Campanian? = Djadokhta
> F.-equivalent), *Claosaurus* (u.Campanian?), the
> previously-noted La Solana, España, jaw and teeth
> (Upper Cretaceous, Company et al., 1998: _Oryctos_
> 1:121-128), *Orthomerus* (Maastrichtian),
> *Ouranosaurus* (l.Aptian), and *Probactrosaurus* (var.
> spp. all u.Lower Cretaceous, *Psittacosaurus*
> horizons) all demonstrate that relatively rapid
> differentiation of hadrosaur-like iguanodntians within
> the last 30my of the Cretaceous, but that the actual
> origin of these forms stemmed from the Laurasian of
> the Early Cretaceous, and spread elsewhere. The
> earliest forms are from America and Mongolia, as well
> as Africa, and these forms may have spread from one
> Laurasian continent to the other, and differentiating
> the unique *Ouranosaurus* on the way. It is my thought
> that the faunal differentiation went something like
> this:
>
>
>   Mongolia -> Europe --> Africa
>                      \_> NAmerica -> SAmerica
>
>   or more linearly:
>
>   Mongolia -> Europe -> Africa -> SAmerica -> NAmerica
>
>   Relatively wide-spread skeletal plesiomorphies are
> possibly responsible for the wide array of very
> similar forms from most continents. Cranial remains
> exhibit the most differentiation, as suggested by the
> number of different taxa named from similar skulls
> that exhibit slight changes, or from similar forms
> with highly distinct cranial changes.
>
>   Anyway, my .02c,
>
> =====
> Jaime "James" A. Headden
>
>   Dinosaurs are horrible, terrible creatures! Even the
>   fluffy ones, the snuggle-up-at-night-with ones. You think
>   they're fun and sweet, but watch out for that stray tail
>   spike! Down, gaston, down, boy! No, not on top of Momma!
>
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