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E&P of Pteros 6 - notes



Hi, back again, and thanks for all the walking pterosaur mpeg requests.



New morphological observation on Triassic pterosaurs, Dalla Vecchia

Here Fabio reviews the record of Triassic pterosaurs, corrects some
previous errors and emphasizes certain important characters. As Fabio
noted, several specimens need to be lumped with others, while others
need to split apart.

Interesting that many of the Lombardy specimens were collected from a
bed only 15 cm thick, and that all Triassic pteros were nearly
contemporary with one another. I find that fascinating.

Much of the text deals with tarsals and carpals and their various
degrees of fusion. Also remarks are made regarding the various sorts of
?bundles? [of hyperelongated caudal zyopopheses and hemals] or the lack
thereof. All good cladistic material it would seem.

The problems of Peteinosaurus are considered for many paragraphs.
Preondactylus  is briefly considered and Austriadactylus is barely
mentioned.

Dalla Vecchia considered the holotype of E. ranzii to possibly be a very
old or giant individual, primarily owing to its comparatively great
size. I have found that cladistically it is the most derived of the
Triassic forms, rather than a giant of its genus.

Dalla Vecchia sees signs of immaturity in a number of Triassic
specimens, including all of the putative peteinosaurs, some of the
Eudimorphodons and Preondactylus. One of the most obvious signs of
immaturity has been non-fusion of the scapula and coracoid. If you
consider nonfusion of the scapula and coracoid in a MacClade matrix, an
interesting pattern emerges [and here I count a scapula and coracoid as
?fused? if they are found in their natural association with one another,
that is, not separated -- even though a strong line of demarcation can
still be seen between them].

Scapulocoracoid fusion does not occur in Longisquama or Sharovipteryx,
but does occur in the basal most pterosaurs. It occurs in basal
dimorphodontids (D. macronyx), but not in smaller dimorphodontids (MCSNB
8950, Preondactylus). It occurs in basal anurognathids (?Peteinosaurus
3359, ?E. rosenfeldi, and ?D. weintraubi, but not in higher
anurognathids. It occurs in Campylognathoides + Rhamphorhynchus, and in
basal Dorygnathus, but not in higher Dorygnathus, and their smaller
descendents among the pre-azhdarchids and pre-ctenochasmatids.
Azhdarchids redevelop fusion. Fusion occurs in Sordes, Pterorhynchus and
basal scaphognathids, but at the size squeeze it no longer occurs. Among
scaphognathid descendents, the ornithocheirids, on the one hand, grew
phylogenetically larger, but only one clade reacquired fusion, the rest
did not. The pterodactylids did not redevelop fusion, but their larger
sisters, the germanodactylids did. In one branch of germanodactylids
that maintained size, the dsungaripterids + tapejarids, fusion was
retained. In another branch that had some small members, or went through
another size squeeze, fusion was lost then regained in Pteranodon, but
not in Nyctosaurus. Anyway, PAUP revelations like this need to be looked
at because paedomorphosis seems to reduce fusion for many small pteros.
Contrary to current thinking, these may not be juveniles. They all show
sufficient morphometric differences to indicate that we are dealing with
separate species or even genera. None have been irrevocably linked to
established adult species.

According to PAUP, Dalla Vecchia is correct when he notes that
Preondactylus, Peteinosaurus, MCSNB 8950 and Dimorphodon may form a
clade. He is also correct (and thank you Fabio, for noting this) that
Triassic pterosaur feet are morphometrically not the same as Jurassic
pterosaur feet and would not have made the same sorts of footprints.


>>>>>>

A new crested ornithocheirid from the Lower Cretaceous of northeastern
Brazil and the unusual death of an unusual pterosaur -- Frey, Martill
and Buchy

Ludodactylus is known from a great skull with teeth _and_ a cranial
crest, and with a giant leaf lodged between its mandibles. This was
probably its cause of death, according to the authors. It?s a short
paper, but well done. The only thing I would have to say is that more
attention needs to be paid to overlooked features on the rostrum of
these ornithocheirids.

>>>>>>>>

A new species of tapejarid pterosaur with soft tissue head crest --
Frey, Martill and Buchy

Here another South American skull, this time two specimens of Tapejara,
both known from skulls with potentially enormous soft tissue crests.
Only a broken matrix slab prevents us from knowing the full dimensions.

A diagram shows a selection of pterosaurs with smooth margin crests and
a selection with striated laemellae, and one without bony support. I
used to wonder why Pteranodon, with its sharp rostrum and lack of a soft
tissue crest was different from the otherwise similar dsungaripterids
and tapejarids. Then PAUP explained it all.

Another chart displays the problems T. navigans might have encountered
in a head wind (which is all the time in flight) without offering a
solution other than it must have come from the wings and legs. Didn?t
Paul Macready solve this problem with his airborne Quetzalcoatlus?

>>>>>>>


Pterosaur (Pteranodontoidea, Pterodactyloidea) scapulocoracoid from the
Early Cretaceous of Venezuela -- Kellner and Moody.

Not much to say. They got one and it can be attributed to something like
C. spielbergi, with available data. The scap/coracoid is fused.


>>>>>>>

A new azhdarchid pterosaur from the Late Cretaceous phosphates of
Morocco.

Again, not much to say. It?s a nice set of cervicals. It is interesting
to note that on this and another paper (Bonde and Christiansen), the
cervical count is give as 9. The ninth ?cervical? bears elongated ribs
that do not reach the sternal complex, hence the identification as a
cervical. A reconstruction, however shows that ?cervical? nine and its
ribs would fall within the chest cavity. And in most pterosaur ancestors
among the prolacertiforms (save Tanystropheus and Tantrachelos, but
that?s a different story), clearly only eight cervicals are seen. It?s
all in how you look at it I suppose.


More later,
Footprint stuff, coming up.
David Peters