[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Hadrosaur Relationships



I have been working on the inter-relationships of hadrosaurs on and 
off for a while and have made a cladogram of their relationships (in 
my opinion).  What do you all think (I know you just couldn't wait for 
me to post something on dinosaur relationships again Dr. Holtz :).

Hadrosauria
~Probactrosauridae
~~~Probactrosaurus
~Lambeosauridae
~~Bactrosaurinae
~~~Bactrosaurus
~~~Shantungosaurus?
~~Lambeosaurinae
~~~Lambeosaurus
~~~Corythosaurus
~~~Hypacrosaurus
~~~Parasaurolophus
~~~Jaxartosaurus
~~~Nipponosaurus
~Hadrosauridae
~~Telmetosaurinae
~~~Telmetosaurus
~~~Maiasaura
~~Hadrosaurinae
~~~Hadrosaurus
~~~Kritosaurus or Gryposaurus (not even thinking about getting
             involved in that mess)
~~~Aralosaurus
~~~Brachylophosaurus
~~Edmontosauridae
~~~Prosaurolophus (=Lophorhothodon?)
~~~Saurolophus
~~~Edmontosaurus
~~~Anatotitan

Hadrosaurians are Iguanodontians that have lost manual digit I and 
no longer have the palpabral bone sticking out of the orbit.  
Probactrosauridae is pretty much all hadrosaurs that aren't 
Hadrosaurids or Lambeosaurids (the sole candidate being (surprise): 
Probactrosaurus).  Lambeosaurids are Hadrosaurians that have a 
robust distal ischium and a deep jugal.  Bactrosaurines have 
elongated dorsil spines of the sacral and caudal vertibrae.  
Lambeosaurines have their external nares completely enclosed by 
the premaxila.  Hadrosaurids have gracile distal ischia and shallow 
jugals.  Telmetosaurines have small external nares and depressed 
nasals; and are the sister taxon to Hadrosaurinae + 
Edmontosaurinae.  Hadrosaurines have large external nares, raised 
nasals, and the joint between the nasals and premaxila roughly in the 
center of the external nares.  Edmontosaurines have large external 
nares, raised nasals, and the joint between nasals and premaxila at 
the front end of the external nares.

I do not place Gimorosaurus, Tanius, Claosaurus, Secernosaurus, 
Barsboldia, or Tsintaosaurus anywhere because... I don't have any 
information on them (I'm not going to lie).  I have a feeling that 
Tsintaosaurus might be an Edmontosaurine close to Prosaurolophus, 
and that Prosaurolophus is closer to Edmontosaurus + Anatotitan 
than either is to Saurolophus.  I put Shantungosaurus with 
Bactrosaurus because they both have a sort-of dorsal frill above their 
hips, and robust skeletons in general.  My most recent reference is 
"The Dinosauria," and I know that a lot of Hadrosaur stuff has been 
found and named recently.

So.... what do you all think?  Dr. Holtz, I'm waiting for you to put 
Segnosaurs somewhere in this cladogram (just kidding :).

Peter Buchholz
Stang1996@aol.com