E&P of Pterosaurs Notes - 5

[david peters <davidrpeters@earthlink.net>]

E&P of Pterosaurs Notes - 5

New Scaphognathine Pterosaur from Wyomng, USA - Carpenter, et al.

DMLer, Ken Carpenter and his team have uncovered a new rhamph-grade rostrum and 
dentary tip from the Morrison Fm. with a low crest and distinctive dentition 
(as determined by alveoli spacing). Harpactognathus is the name of the new 
genus and the authors have allied it with the scaphognathines based on tooth 
count, dorsoflexion of the anterior of the rostrum so that the the profile of 
the palate curves dorsally to meet the dorsal margin of the skull at an obtuse 
angle, and the crest, which appears imminent in Scaphognathus.

Also present is a recessed palatal shelf (= a descending maxilla wall), a 
strong scalloping of the dental margin when viewed dorsally, and a deep dorsal 
emargination (= uneven outline) of the jawline posterior to the premaxilla (the 
fifth alveolus). 

A mandible tip of similar size was also found within the same quarry as the 
rostrum, but due to its shallow and narrow shape, and closely spaced alveoli, 
which do not match the rostrumâ??s wider-than-tall shape and much wider alveoli 
spacing, it was not considered from the same specimen -- but interestingly it 
was illustrated with it in Fig. 4.         :  )

Although the authors report that the palatal shelf is almost flat and 
continuous with no discernable sutures, the division between the premaxilla, 
vomers and palatal shelves seem to be apparent in the photograph. They look 
like cracks, but I recognize the cracks.

Also I question the placement of this specimen within the scaphognathines. For 
one, just the rostral fragment of Harpactognathus is about the size of the 
largest Scaphognathus skull. Not that size is the primary issue, but it appears 
that the scaphognathines were a smaller group.

Another clade/grade is similar in overall size and appears to have all of the 
characters seen in Harpactognathus, this time including the narrow, toothy 
mandible tip. A specimen of Dorygnathus SMNS 50164 is basal to this group. 
Others include SMNS 55886, R 156 and Parasicephalaus purdoni, plus another 
similar but unpublished specimen found on the Paleotek website: 

http://www.fossilien-sammler.de/sammler/Fundstellen/Altdorf.htm

The latter seems particularly intriguing because in dorsal view the jawline is 
similarly scalloped. Anyway, just an alternative thought, perhaps worth 
pursuing. Unwin is right in noting that Parapsicephalus purdoni nests within 
Dorygnathus, but it is also important to note that Dorygnathus is somewhat of a 
wastebasket taxon with generic differences worthy of note appearing in certain 
specimens. A revision is needed here. 

David Peters
St. Louis