Re: New Hadrosauroids from China

["Nicholas Gardner" <ratites637@hotmail.com>]

Alessandro Marissa wrote:
> Hi to all the List-Members for all the Hadrosauroids fun

Because hadrosauroids (and ornithopods) are so darn fun!

Also, someone earlier asked about the systematic position of Eolambia.  I 
meant to reply earlier but was not able to do so.

> From Head (2001: Fig. 3)---

--+--Iguanodon
 |--Ouranosaurus
 `--+--Altirhinus
    `--+--+--Probactrosaurus
       |  `--Eolambia
       `--+--Protohadros
          `--+--Telmatosaurus
             `--+--Gilmoreosaurus
                `--+--Bactrosaurus
                   `--+--Lambeosaurinae
                      `--Hadrosaurinae

> From Norman (2002: Fig. 34)---

--+--Dryosaurus
 |--Camptosaurus
 `--+--Lurdusaurus
    |--Equijubus
    `--+--Iguanodon bernissartensis
       `--+--Iguanodon atherfieldensis
          `--+--Ouranosaurus
             `--+--Altirhinus
                |--Eolambia
                `--+--Protohadros
                   `--+--Probactrosaurus
                      `--+--Telmatosaurus
                         `--+--Bactrosaurus
                            `--+--+--Parasaurolophus
                               |  `--Corythosaurus
                               `--+--Saurolophus
                                  `--+--Brachylophosaurus
                                     `--Edmontosaurus

> From Kobayashi & Azuma (2003: Fig. 7)---

--+--+--Iguanodon
 |  `--Ouranosaurus
 `--+--Fukuisaurus
    `--+--Altirhinus
       `--+--Pactrosaurus
          `--+--Eolambia
             `--+--Protohadros
                `--+--Bactrosaurus
                   |--Telmatosaurus
                   `--+--Lambeosaurinae
                      `--Hadrosaurinae

> From You et al. (2003: Fig. 3)---

--+--Hypsilophodon
 `--+--Dryosaurus
    `--+--Camptosaurus
       `--+--+--Iguanodon
          |  `--+--Ouranosaurus
          |     `--Altirhinus
          |--Jinzhousaurus
          `--+--Equijubus
             `--+--Probactrosaurus
                `--+--Bactrosaurus
                   `--+--Protohadros
                      `--+--Telmatosaurus
                         `--+--Prosaurolophus
                            `--Corythosaurus

Okies... in the past few days, I've added Fukuisaurus and Jinzhousaurus to 
Norman's (2002) analysis.

Heuristic Search (12 MPTs, 127 steps)

--+--Dryosaurus
 |--Camptosaurus
 `--+--Lurdusaurus
    |--Jinzhousaurus
    `--+--+--Iguanodon atherfieldensis
       |  `--+--Iguanodon bernissartensis
       |     `--Ouranosaurus
       `--+--Equijubus
          `--+--Protohadros
             |--Altirhinus
             |--Eolambia
             `--+--Probactrosaurus
                `--+--Telmatosaurus
                   `--+--Bactrosaurus
                      `--+--+--Parasaurolophus
                         |  `--Corythosaurus
                         `--+--Saurolophus
                            `--+--Edmontosaurus
                               `--Brachylophosaurus

Adding these two taxa seems to alter the tree in the following ways-

- Equijubus becomes a hadrosauroid (as opposed to a non-hadrosauriform 
ankylopollexian).
- Eolambia, Protohadros, and Eolambia fall together in a polytomy with more 
derived hadrosauroids (as opposed to be arranged in a gradual line to the 
Probactrosaurus + Hadrosaurids clade).
- Monophyletic Iguanodontidae with Ouranosaurus and the two species of 
Iguanodon (as opposed to paraphyletic Iguanodontidae with Ouranosaurus and 
I. atherfieldensis closer to other hadrosauroids).

Support for the Iguanodontidae:

16(1).  Strongly angular ventral edge of jugal.
34(1).  Maxillary crowns narrower than dentary crowns.

The former character is developed also in Protohadros and Eolambia. The 
latter character is also a synapomorphy of all hadrosauroids more derived 
than Equijubus.

Feel free to inquire questions or request the nexus file.

Nick Gardner

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