Re: Prosauropods

["Mickey Mortimer" <Mickey_Mortimer111@msn.com>]

Jean-Michel BENOIT wrote-

> Hi all, no more posts from my previous address, this one is the new one.
> I was wondering what characters definitely anchor prosauropods, if proved
to
> be monophyletic, within sauropodomorpha. Their status is still debated,
> IIRC, and some out there in the scientific spheres (into which,
> unfortunately, I'm not) think they're at best paraphyletic and others
> polyphyletic.

No one thinks prosauropods are polyphyletic anymore, there have certainly
been no phylogenetic analyses that support it.  Sereno (1999) and Galton
(2001) find Prosauropoda to be monophyletic, while Langer (2001) and Yates
(2001) find it to be paraphyletic to sauropods.  All are unpublished except
Sereno's, who listed the following sauropodomorph synapomorphies-
73. External naris size: small (0); large (1).
74. Maxilla borders external nares: present (0); absent (1).
75. Narial fossa, ventral width: narrow, above subnarial foramen when
present (0); deep, including subnarial foramen when present (1).
76. Premaxillary posterolateral process, articulation: lateral aspect of
snout (0); dorsal aspect of maxillary anteromedial process (1).
77. Anterior maxillary foramen: absent (0); present (1).
78. Antorbital fossa, posterior portion of medial wall: present (0); absent
(1).
79. Supra-jugular foramen: absent (0); present (1).
80. Proximal carpals (and distal carpal 4): present (0); very reduced or
absent (1).
81. Ilium, pubic peduncle length: less (0), or more (1), than twice the
distal width of the peduncle.
82. Ilium, axis of the pubic peduncle: straight (0); arched (1).
83. Ilium, ventral acetabular flange: present (0); absent (1).
84. Astragalus, fibular facet orientation: dorsolateral (0); lateral (1).
85. Pedal digit I, ungual length: shorter (0), or longer (1), than other
pedal phalanges.
86. Metatarsal V, proximal shaft width: narrow (0); expanded transversely
(1).

Mickey Mortimer