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Pterodactyloids may not have been monophyletic
I've been looking into the phylogeny of pterosaurs today and have come up
with an interesting observation. I think pterodactyloids may *not* have been
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_ are
The rest of the pattern seems to go like this.
Group one, consisting of sharp-snouted "rhamphorhynchoids" (_Rhamphorhynchus,
Campylognathoides_) and sharp-snouted "pterodactyloids" (_Nyctosaurus,
Pteranodon, Germanodactylus, Tapejara, Anhanguera, Tupuxara, Dsungaripterus_)
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 are
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 to
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