[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
not have been monophyletic
In a message dated 95-09-16 19:21:02 EDT, DPterosaur@aol.com writes:
>I've been looking into the phylogeny of pterosaurs today and have come up
>with an interesting observation. I think pterodactyloids may *not* have
What you mean is, pterodactyloids may have been polyphyletic (specifically,
diphyletic). It's not exactly the same thing as "not monophyletic." (Sorry
>The idea began when looking at prepubic bones in pterosaurs. In
>_Campylognathoides_ and _Rhamphorhynchus_ the prepubic bones are tri-radiate
>and strap together medioventrally. In _Nyctosaurus_ and _Pteranodon_ they
>are the same. In contrast, the pre-pubic bones of _Dorygnathus_ are broad
>and fan-shaped anteriorly. Those of _Pterodactylus_ and _Quetzalcoatlus_
>The rest of the pattern seems to go like this.
>Group one, consisting of sharp-snouted "rhamphorhynchoids"
>Campylognathoides_) and sharp-snouted "pterodactyloids" (_Nyctosaurus,
>Pteranodon, Germanodactylus, Tapejara, Anhanguera, Tupuxara,
>also have proportionately longer wings, a longer tail, a shorter neck, and
>were apparently fish-eaters who caught their prey by stabbing it while
>Group two, consisting of round-snouted "rhamphorhyncoids" (_Dorygnathus,
>Angustinaripterus_) and round-snouted "pterodactyloids" (_Pterodactylus,
>Ctenochasma, Gallodactylus, Gnathosaurus, Pterodaustro, and Huanhepterus_)
>also have proportionately shorter wings, a shorter tail and many were filter
>feeders. The "rhamphorhynchoids" in this group seem to have basket caught
>fish while wading, perhaps a way-station toward filter-feeding.
> _Huanhepterus_ with its super-long neck and long beak could be ancestral to
>azdarchids, so _Zhejiangopterus and Quetzalcoatlus_ also belong to group
>two. In these forms, apparently the filter teeth disappeared and an
>edentulous beak, convergent with group one, appears. Either that or they
>direct descendents of _Pterodactylus antiquus_, which seems more likely.
>Other pterodactyloid synapomorphies offered by Bennett (1991) seem to be
>convergent features. (1) The confluent naris and antorbital fenestra seems
>have evolved in two different ways, but I need to learn more on this one.
> (2) The reclined occiput also occurs in "rhamphorhynchoids." (3) Seven
>cervical vertebrae also occurs in certain "rhamphorhnchoids". (4) Tail
>shorter than trunk occurs in at least one "rhamphorhynchoid" and the tails
>(althought far from well-known) seem to fall into two different patterns.
> (5) Length of metacarpus greater than one-half length of antebrachium (ulna
>+ radius)-- true, but possibly convergent in the two groups. No reason
>considered. (6) The pedal digit V with only one short phalanx is prefigured
>I've read some (although not all) of the pterosaur cladograms and family
>trees. I'm looking for someone to shoot me down on this idea with sound
Pterosaur phylogeny is still very unstable, with the British workers at
cross-purposes to Bennett and both at cross-purposes to Kellner. Have fun,
Dave! It's still a free-for-all.
Wouldn't it be nice if Group 1, say, were probably bipedal and Group 2 were
probably quadrupedal? (Not likely.)